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Effective Health Care Program

Noninvasive Testing for Coronary Artery Disease

Research Protocol

Notice: This protocol was amended on December 18, 2014. To view the amendments go to Summary of Protocol Amendments on this page.

Background and Objectives for the Systematic Review

The public health and economic burdens of coronary artery disease (CAD) are substantial. A large proportion of ambulatory health care visits are for evaluation of patients with suspected CAD. Each year, an estimated 1.5 percent of the population presents to primary care providers with chest pain.1 Moreover, CAD is responsible for 8 to 10 percent of emergency department visits. Annually, approximately 635,000 Americans experience a new coronary event, 280,000 will have a recurrent ischemic event, and an additional 150,000 will have a silent first myocardial infarction.2 CAD causes one in six deaths in the United States, and it is the leading cause of death globally.3 An estimated $108.9 billion is spent annually on CAD treatment.4 Reduction in the prevalence, morbidity, and mortality related to CAD is an important public health goal given the significant disease burden and contribution to total health care costs. Accurate, early diagnosis of CAD is important for initiation of appropriate treatment and reduction of CAD-related morbidity and mortality.

A review of the basic pathophysiology of CAD may facilitate appreciation of some of the challenges related to its diagnosis. The underlying cause of CAD is atherosclerosis, a disease process in which plaque (which has a complex and varied composition that includes lipids, inflammatory cells, smooth muscle cells, and connective tissue) builds up within the walls of damaged arteries. Plaque formation can result in the partial or complete blockage of coronary arteries and as a result prevent the heart from receiving blood, oxygen, and vital nutrients. There are two mechanisms by which plaque can cause blockage: 1) progressive narrowing of the artery due to the plaque compromising the vessel lumen and 2) thrombotic occlusion of the artery, which happens when a plaque becomes unstable and exposes its pro-thrombotic milieu to the blood’s clotting elements. In addition, certain risk factors for atherosclerosis (lipid disorders, diabetes) and plaque development itself can lead to abnormal blood flow responses through an imbalance of chemical mediators of vasorelaxation and vasoconstriction, termed vascular dysfunction. The resulting reduction in blood flow, which can be either acute or chronic, leads to an imbalance in the blood supply to the myocardium and the requirements of the myocardium for oxygenated blood either at rest or during exertion.5,6

The most common symptom of obstructive CAD is chest pain (angina), which may be the first presenting symptom in up to at least 50 percent of patients with CAD.7 Other common symptoms associated with coronary artery ischemia include dyspnea or early fatigue with exertion, indigestion, palpitations, tightness in the throat, or neck pain. These symptoms, when documented to be associated with CAD, are called “anginal equivalents.” However, these symptoms are also seen in many common noncardiac conditions including gastroesophageal reflux, esophageal spasm, and cervical disc disease, and they are much less reliable predictors of CAD. Women and people with diabetes are less likely to experience classic angina, adding to the challenges of early diagnosis of CAD in these populations. The onset of symptoms and clinical impact of CAD depend in part on the number and distribution of atheromatous plaques, as well as the degree of narrowing that has occurred; however, lesion severity is poorly correlated with symptoms and CAD may be asymptomatic for many years.

The pathophysiologic changes in coronary artery anatomic structure (including deposition of plaque), vascular function, and myocardial function described above can be evaluated diagnostically. Historically, invasive coronary angiography (ICA) has been considered the standard reference diagnostic test for anatomic CAD and provides information on coronary artery anatomy and lumen obstruction. ICA allows visualization of the size, position, and possible stenotic areas in vessels, and various thresholds for occlusion have been used (e.g., ≥ 50% or ≥ 70% occlusion) for diagnosis of CAD. However, there are a number of drawbacks associated with ICA. Angiography may overestimate or underestimate disease as estimation is influenced by a variety of technical factors as well as the complexity of coronary anatomy and plaque configuration. Many lesions are eccentric, so the apparent degree of stenosis can vary depending on the angle of visualization, and reproducibility on measurement of stenosis is considered only moderate.8-11 Standard ICA also does not necessarily detect outward remodeling of the coronary artery, which may present a situation in which there is a large amount of plaque volume without significant lumen obstruction. Complications of ICA include those related to local anesthesia and use of contrast material, as well as infection, local vascular injury, myocardial infarction, stroke, and death.12 ICA can provide functional information of the degree of flow limitation through a technique called fractional flow reserve (FFR), which relies on the use of specialized catheters placed in the coronary artery to measure a pressure gradient across a blockage during administration of vasodilating medications.

Because of the cost and risk of ICA, noninvasive testing is more appropriate as a first-line diagnostic test for patients presenting with chest pain or other symptoms of IHD and who are deemed to be stable and not experiencing acute coronary events. Noninvasive methods are used as diagnostic and prognostic tools to improve risk stratification of patients for CAD and to guide subsequent testing and interventions. Some types of noninvasive testing (e.g., stress testing) provide additional information not provided by standard ICA, such as whether symptoms are correlated with areas of ischemia, and noninvasive testing may provide important information about functional status. Noninvasive diagnostic tests can be broadly divided into two categories: functional tests and anatomic tests. Functional tests include exercise electrocardiography (ECG), exercise/pharmacologic stress echocardiography, exercise/pharmacologic cardiac nuclear imaging with single photon emission computed tomography (SPECT) or positron emission tomography (PET), pharmacologic stress magnetic resonance imaging (MRI), computed tomography (CT) perfusion, and CT or Doppler ultrasound-derived flow reserve measurements. There is also increasing interest in noninvasive anatomic tests, including coronary CT angiography (CCTA), coronary magnetic resonance angiography (MRA), and coronary artery calcium scoring (CACS).

Deciding when and how to order the most appropriate test for diagnosing CAD in symptomatic patients is not a simple matter. The first step is assessing pre-test likelihood that the patient has CAD. While there are a number of standard risk assessment tools, in clinical practice the clinician’s overall assessment of sociodemographic characteristics (e.g., sex, age) and characteristics of the chest pain (i.e., typical or atypical) is the most accurate assessment of pre-test likelihood of CAD.

The 2012 American College of Cardiology Foundation/American Heart Association (ACCF/AHA) guideline states that diagnostic testing is most valuable when the pre-test probability of IHD is intermediate (10%–90%) and provides a range of options for which test may be used in a given scenario. However, the guideline does not directly compare the effectiveness of different modalities with regard to impact on clinical outcomes.8 Further, variation exists in terms of which initial (and additional) diagnostic tests are performed in patients presenting with intermediate risk of CAD. Because patients considered to have a low pre-test likelihood risk of CAD are clinically distinct from those at intermediate risk, and pre-test likelihood of disease will impact a test’s ability to predict or improve clinical outcomes, patient outcomes following diagnostic testing should be evaluated separately in these patient sets. Three primary areas of uncertainty remain regarding which tests may be most suitable and most beneficial for specific patient scenarios in patients who present with symptoms suggestive of CAD but have no prior history of it. Namely:

  • In patients with low pre-test probability of CAD (<10%), are clinical outcomes improved by use of non-imaging stress testing, imaging stress testing, or no further testing? It is not clear whether imaging may be necessary in this group of patients or if there are specific subgroups of low-risk patients who might benefit more from one type of testing or no further testing.
  • How do tests compare with regard to improvement in clinical outcomes in very low or low risk patients? How do tests compare in intermediate to high risk patients? Important clinical outcomes include prevention of myocardial infarction (MI), premature mortality, and congestive heart failure.
  • Are there differences in clinical outcomes following anatomic versus functional testing in either of the above risk groups?

An ideal test is one that is safe, sensitive, and specific and for which efficacious treatment is available for test-positive people. The overarching goals of treatment for CAD are to minimize the likelihood of death while maximizing health and function.8 The primary categories of treatment are medical therapy (e.g., use of lipid lowering agents) and revascularization (e.g., coronary artery bypass grafting or percutaneous coronary intervention with stents). Counseling on modifiable lifestyle and risk factors is a part of both therapeutic approaches and may be sufficient in some patients (e.g., low risk patients). Decision making regarding next steps following a positive result from an initial noninvasive test is complex and there are many nuances to determining when the threshold for revascularization versus medical therapy has been crossed which are beyond the scope of this systematic review.

In general, next steps following a positive result from an initial noninvasive test is in part based on the post-test annual predicted rate of cardiac mortality as described in the 2012 ACCF/AHA guideline: low risk (<1% per year), intermediate risk (1% to 3% per year), or high risk for cardiac mortality (>3% per year).8 Clinical presentation and test results are both considered in this determination. Persons who would be categorized as being at low or intermediate risk and who do not exhibit characteristics of acute coronary syndrome may be appropriate for medical management. In most instances, patients in these categories can be managed without invasive assessment. In patients who are considered to be at high risk based on noninvasive testing and presentation, invasive coronary angiography for further risk stratification and assessment of appropriateness for revascularization may be the next logical steps. In general, indications for revascularization are based on the clinical presentation (acute coronary syndrome or stable angina), the severity of the angina (based on Canadian Cardiovascular Society Classification), the extent of ischemia on noninvasive testing, and the presence or absence of other prognostic factors including congestive heart failure, depressed left ventricular function, and diabetes, the extent of medical therapy, and the extent of anatomic disease.13,14

Review Objective:

To assess the effectiveness of noninvasive technologies for the diagnosis of CAD or dysfunction that results in symptoms attributable to myocardial ischemia in patients who present with signs or symptoms suggestive of CAD, whose condition is considered to be stable, and who have no known history of CAD.

The intended focus is on clinical outcomes and clinical pathways following the first diagnostic test performed as result of initial risk assessment (which includes clinical presentation and physical exam, family history of CAD, and findings on resting ECG). Harms related to both the initial test as well as subsequent testing will be evaluated. The specific tests to be covered will be restricted to those identified as widely available and most clinically applicable and established. Screening applications of tests are excluded from this report as the U. S. Preventive Services Task Force covers screening in its recommendations. Consideration of medical-legal questions related to use or failure to use testing is beyond the scope of this review as is detailed discussion of the implications and thresholds for post-test clinical decisionmaking related to management options.

Information on traditional measures of accuracy (e.g., sensitivity and specificity) of noninvasive tests versus the historically accepted gold standard of ICA will be presented for context in the background rather than as a primary question of this report for several reasons. First, these parameters are considered intermediate outcomes. Furthermore, the primary gaps in the current ACCF/AHA guidelines include lack of information regarding how noninvasive tests may influence clinical decisionmaking and impact clinical outcomes. Next, there is controversy regarding the suitability of ICA as a gold standard to which noninvasive tests should be compared based on the moderate reproducibility of ICA, use of varying diagnostic thresholds for determining the presence and degree of obstructive CAD, and the inability of ICA to predict future acute coronary syndromes. Another drawback of comparing noninvasive tests to ICA is that ICA (with or without FFR) is more commonly used in those with known CAD, or those with acute coronary syndromes who present with unstable angina and elevated serum cardiac biomarkers suggestive of high risk for acute myocardial infarction versus the population of interest of this review (i.e., those with stable symptoms who are at low or intermediate to high risk of CAD and have not been previously diagnosed with CAD). Finally, there are a number of previously published systematic reviews and meta-analyses that have compared various noninvasive tests to ICA and to each other that are available to provide information on traditional parameters of test accuracy (e.g., sensitivity, specificity). Synthesized data from high quality systematic reviews on these traditional diagnostic accuracy parameters will provide foundational information for answering the Key Questions while allowing the review to focus on primary clinical outcomes.

The review will provide an updated synthesis of currently available evidence and gaps in evidence comparing noninvasive tests in people with suspected but not yet diagnosed CAD that may be helpful to inform clinical practice and guideline development.

Key Questions

Significant revisions to the Provisional Key Questions that resulted from the previous Topic Refinement are proposed. The overarching conceptual flow for initiating noninvasive testing based in risk assessment following initial clinical evaluation provides context for the Key Questions (Figure 1). There are multiple general decision points and options for the use of noninvasive testing, the most common of which are delineated in Figure 1. The primary decision points relate to which tests may be best based on the pre-test risk determined via clinical evaluation; these points include the physical exam, assessment of symptoms and presentation, history, and resting ECG. Based on the pre-test risk, the key questions seek to compare tests’ ability to improve clinical outcomes while considering harms and how tests may be used in clinical decisionmaking.

Figure 1. Overarching conceptual flow for initiating noninvasive testing based on risk assessment following initial clinical evaluation

This figure is a flow diagram that provides an overview of the conceptual flow for initiating noninvasive testing based on risk assessment following the initial clinical evaluation. The diagram delineates the most common general decision points and options for the use of noninvasive testing based on risk assessment. At each decision point in the diagram, an arrow points to the next step or steps in the process. When a person presents with symptoms suspicious for coronary artery disease (CAD) (far left of diagram) they undergo a clinical evaluation which consists of a physical exam, history, and a resting electrocardiogram (ECG). Based on the results of the clinical evaluation, a person will be categorized into one of three pre-test risk categories: intermediate or high risk, low risk, or very low risk. Those considered to be at intermediate or high risk go on to have either functional or anatomic imaging. For those considered to be at low risk, the type of testing they receive depends on their resting ECG results. If their ECG was abnormal, functional imaging, anatomical imaging, or no further testing are considered; if their ECG was normal, stress ECG, anatomic imaging, or no further testing are considered. Lastly, those at very low risk go on to have stress ECG either with or without imaging or no futher testing.

CAD = coronary artery disease; ECG = electrocardiogram; PE = physical exam.

The final Key Questions are as follows:

In stable, symptomatic patients with suspected CAD who do not have previously diagnosed CAD and who have had a resting ECG:

  1. For patients considered to be at very low or low risk for CAD, what is the comparative effectiveness of anatomic tests (compared with each other, standard of care, or no testing):
    1. For improving primary clinical health outcomes (e.g., quality of life, avoiding myocardial infarction)? In the absence of comparative studies linking testing with outcomes, do the tests predict future clinical events (predictive accuracy)?
    2. What are the adverse effects, consequences, or harms of testing?
    3. How do noninvasive tests differ in terms of clinical management based on test results, including referral for coronary angiography or additional noninvasive testing?
    4. What harms are associated with additional testing following anatomic tests?
    5. Is there differential effectiveness or harm based on patient characteristics (e.g., sex, age, comorbidities)?
  2. For patients considered to be at very low or low risk for CAD, what is the comparative effectiveness of functional tests (compared with each other, standard of care, or no testing):
    1. For improving primary clinical health outcomes (e.g., quality of life, avoiding myocardial infarction)? In the absence of comparative studies linking testing with outcomes, do the tests predict future clinical events (predictive accuracy)?
    2. What are the adverse effects, consequences or harms of testing?
    3. How do noninvasive tests differ in terms of clinical management based on test results, including referral for coronary angiography or additional noninvasive testing?
    4. What harms are associated with additional testing following anatomic tests?
    5. Is there differential effectiveness or harm based on patient characteristics (e.g., sex, age, comorbidities) or the patient’s ability to exercise?
  3. For patients considered to be at intermediate to high risk for CAD, what is the comparative effectiveness of anatomic tests (compared with each other standard of care, or no testing):
    1. For improving primary clinical health outcomes (e.g., quality of life, avoiding myocardial infarction)? In the absence of comparative studies linking testing with outcomes, do the tests predict future clinical events (predictive accuracy)?
    2. What are the adverse effects, consequences, or harms of testing?
    3. How do noninvasive tests differ in terms of clinical management based on test results, including referral for coronary angiography or additional noninvasive testing?
    4. What harms are associated with additional testing following anatomic tests?
    5. Is there differential effectiveness or harm based on patient characteristics (e.g., sex, age, comorbidities)?
  4. For patients considered to be at intermediate to high risk for CAD, what is the comparative effectiveness of functional tests (compared with each other, standard of care, or no testing):
    1. For improving primary clinical health outcomes (e.g., quality of life, avoiding myocardial infarction)? In the absence of comparative studies linking testing with outcomes, do the tests predict future clinical events (predictive accuracy)?
    2. What are the adverse effects, consequences, or harms of testing?
    3. How do noninvasive tests differ in terms of clinical management based on test results, including referral for coronary angiography or additional noninvasive testing?
    4. What harms are associated with additional testing following anatomic tests?
    5. Is there differential effectiveness or harm based on patient characteristics (e.g., sex, age, comorbidities) or the patient’s ability to exercise?
  5. What is the comparative effectiveness of anatomic tests versus functional tests in those who are at very low or low risk for CAD?
    1. For improving primary clinical health outcomes (e.g., quality of life, avoiding myocardial infarction)?
    2. What are the adverse effects, consequences or harms of testing?
    3. How do noninvasive tests differ in terms of clinical management based on test results, including referral for coronary angiography or additional noninvasive testing?
    4. What harms are associated with additional testing following anatomic tests?
    5. Is there differential effectiveness or harm based on patient characteristics (e.g., sex, age, comorbidities) or the patient’s ability to exercise?
  6. What is the comparative effectiveness of anatomic tests versus functional tests in those who are at intermediate to high risk for CAD?
    1. For improving primary clinical health outcomes (e.g., quality of life, avoiding myocardial infarction)?
    2. What are the adverse effects, consequences or harms of testing?
    3. How do noninvasive tests differ in terms of clinical management based on test results, including referral for coronary angiography or additional noninvasive testing?
    4. What harms are associated with additional testing following anatomic tests?
    5. Is there differential effectiveness or harm based on patient characteristics (e.g., sex, age, comorbidities) or the patient’s ability to exercise?

PICOTS

Table 1 below describes the inclusion and exclusion criteria for patients, interventions, comparators, outcomes, timing of testing, settings, and study design (PICOTS).

Patient Population of Interest and Pre-Test Risk of CAD:

Stable, symptomatic patients with suspected CAD who do not have previously diagnosed CAD and who have had a resting ECG. The definitions of risk categories are based on those described in the ACCF/AHA 2012 Guideline.8 In general, patient presentation and symptoms are primarily used to inform pre-test probability in the population of interest. The review will attempt to stratify studies based on these characteristics if definitions are not provided.

  • Include patients whose risk for CAD may be considered as follows:
    • Those considered to be at very low or low risk of CAD based on having none or only one of the following:
      • Patient age and gender (female <65 years old, male <55 years old)
      • Negative family history for CAD
      • < 2 CAD risk factors (including hypertension, diabetes, smoking, dyslipidemia, metabolic syndrome)
      • New onset angina/chest pain (including noncardiac or atypical chest pain, angina equivalents, unstable angina without non-ST-segment elevation myocardial infarction [NSTEMI], ST-segment elevation myocardial infarction [STEMI])
      • Normal or non-diagnostic resting ECG
    • Those considered to be at intermediate to high risk of CAD based on having two or more of the following:
      • Patient age and gender (female ≥ 65 years old, male ≥ 55 years old)
      • Positive family history for CAD
      • ≥ 2 CAD risk factors (including hypertension, diabetes, smoking, dyslipidemia, metabolic syndrome)
      • New onset or progressive angina/chest pain or those with prolonged angina at rest (or relieved with rest or nitroglycerin) or nocturnal angina (angina including typical, atypical, definite, probable)
      • Possible ECG changes (e.g., T-wave, NSTEMI) or nondiagnostic ECG
      • Presence of other vascular disease (carotid disease, peripheral artery disease [PAD])
  • Exclude patients with any of the following characteristics:
    • Unstable angina with elevated serum cardiac biomarkers, ECG changes, etc.
    • Definite acute coronary syndrome (ACS), Non-ST-Elevation Acute Coronary Syndromes (NSTE-ACS), NSTEMI, STEMI
    • Asymptomatic patients, including those being screened prior to surgery

Interventions

This systematic review will focus on widely available noninvasive tests used for diagnosis of CAD or dysfunction that results in symptoms attributable to myocardial ischemia. Coronary artery calcium scoring has been included since it has been proposed primarily for its ability to EXCLUDE the presence of obstructive disease but not necessarily to confirm the presence of flow-limiting stenosis.

Interventions for inclusion are:

  • Functional tests (including exercise, vasodilator and/or dobutamine as stressor where appropriate)
    • Exercise electrocardiogram without imaging
    • Exercise/pharmacologic echocardiography (with or without myocardial echo contrast)
    • Exercise/pharmacologic cardiac nuclear imaging
    • SPECT
    • PET
    • Pharmacologic stress MRI
    • CT perfusion
  • Anatomic imaging
    • Coronary calcium scoring via electron beam CT (EBCT) or multidetector CT (MDCT)
    • CCTA

Comparators

Comparisons between noninvasive tests included in the interventions; comparisons with no testing or standard of care. (Contextual information will be provided in the background only for comparisons of noninvasive tests with invasive coronary angiography with or without FFR and for comparison between noninvasive tests on traditional diagnostic test measures such as sensitivity and specificity.)

Outcomes

  • Clinical outcomes
    • Quality of life (QOL)
    • Change in angina (e.g., worsening)
    • MI
    • Heart failure
    • Stroke
    • Death
    • Hospitalization for cardiovascular events (acute coronary syndrome, heart failure, arrhythmias)
    • Dysrhythmia
  • Intermediate outcomes
    • Need for additional testing (including referral for invasive testing)
    • Management based on revised post-test risk stratification, including:
      • Guideline-directed medical therapy (GDMT), including management of lipids, blood pressure, and diabetes; counseling related to diet, physical activity, smoking cessation, alcohol use, and management of psychological factors; use of additional therapies to reduce risk of MI and death (e.g., antiplatelet therapy).
      • Any need for subsequent revascularization (percutaneous coronary intervention [PCI] or coronary artery bypass grafting [CABG])
  • Harms, risks and consequences of testing
    • Procedural harms, adverse events of testing (e.g., renal failure, allergy, nephrogenic systemic fibrosis, contrast-related harms, adverse reactions to drugs for stress tests), vascular complications
    • Consequences of testing (e.g., radiation exposure, psychological consequences, consequences of additional testing or incidental findings)

Setting

Nonemergent inpatient settings or ambulatory/outpatient settings, including emergency department

Timing

At time of first test for evaluation using a noninvasive test other than resting ECG

Table 1. PICOTS – Inclusion and exclusion criteria
Inclusion Exclusion
BMIPP = beta-methyl iodophenyl pentadecanoic acid; CABG = coronary artery bypass grafting; CAD = coronary artery disease; CCTA = coronary computed tomography angiography; CT = computed tomography; EBCT = electron beam computed tomography; ECG = electrocardiography; FDA = U.S. Food and Drug Administration; FDG-PET = Fludeoxyglucose (18F) positron emission tomography; FFR = fractional flow reserve; HIV = human immunodeficiency virus; LBBB = left bundle branch block; MDCT = multidetector computed tomography; MI = myocardial infarction; MRA = magnetic resonance angiography; MUGA = multigated acquisition scan; NSTE-ACS = Non-ST elevation acute coronary syndromes; NSTEMI = Non-ST-segment elevation myocardial infarction ;PCI = percutaneous coronary intervention; PET = positron emission tomography; PTCA = percutaneous transluminal coronary angioplasty; RCT = randomized controlled trial; SPECT = single photon emission computed tomography; STEMI = ST-segment elevation myocardial infarction; TEE = transesophageal echocardiography.
Patients Adult patients (≥ 18 years of age) with suspected CAD who present with stable (non-emergent) typical or atypical symptoms suspicious for CAD (e.g., chest pain, chest tightness, chest burning, shoulder pain, palpitations, jaw pain, or non-chest pain symptoms, such as dyspnea or worsening effort tolerance) and who are considered to be at very low, low, or intermediate to high risk of CAD based on initial clinical assessment (including resting ECG) prior to first noninvasive test.

Special populations and circumstances of interest include:
  • Patients with renal insufficiency, diabetes, LBBB, HIV, or other comorbidities
  • Women
  • Those who are/are not able to exercise
  • Those with atypical symptoms/atypical presentation
  • Socioeconomic factors
  • Clinical setting (e.g., emergency department, outpatient clinic)
  • Asymptomatic patients
  • Patients with known CAD
  • Patients who have had previous revascularization (CABG, PTCA, stenting)
  • Studies in populations with >20% asymptomatic or with known CAD unless data are stratified by symptom status/CAD status
  • Patients being evaluated for other cardiac diseases (e.g., valvular disease, etiology of cardiomyopathy)
  • Patients with unstable angina who have elevated serum cardiac biomarkers, ECG changes, etc.; those with NSTE-ACS, NSTEMI, STEMI, or definite acute coronary syndrome
Interventions Functional tests (including use of exercise, vasodilator and/or dobutamine as stressor where appropriate):
  • Exercise electrocardiogram without imaging
  • Exercise/pharmacologic echocardiography (with or without myocardial echo contrast)
  • Exercise/pharmacologic radionuclide imaging with SPECT or PET
  • Pharmacologic stress magnetic resonance imaging
  • CT perfusion
Anatomic imaging:
  • Coronary calcium scoring via EBCT or MDCT
  • CCTA
  • Invasive coronary angiography
  • Screening applications of tests (application of tests to asymptomatic people, those who are being evaluated for non-cardiac surgery)
  • CT (other than CT for calcium scoring): studies not using 64-slice or higher resolution
  • Testing for conditions other than evaluation of CAD (e.g., arrhythmia, valvular disease)
  • TEE, intravascular ultrasound
  • Technologies that are not widely available or have not been established or those being assessed for feasibility (e.g., gene expression testing, Corus CAD by CardioDx, myocardial contrast echo, myocardial strain imaging (post-ischemic shortening as a marker for ischemic memory), coronary FDG PET, BMIPP ischemic memory imaging, transthoracic Doppler FFR, CT-based FFR, MRA)
  • Technologies that are no longer available or no longer widely used (e.g., MUGA, planar nuclear imaging)
  • Drugs or devices used in testing that are not available in the United States
Comparators Other noninvasive tests included in the interventions, standard of care, or no testing
  • Invasive coronary angiography
  • Studies which do not specify components of “standard of care” if that is the comparator
Outcomes Clinical outcomes (primary focus):
  • Quality of life
  • Change in angina (e.g., worsening)
  • MI
  • Heart failure
  • Stroke
  • Death
  • Cardiovascular hospitalization for acute coronary syndrome, heart failure, arrhythmias
  • Dysrhythmia
Intermediate outcomes:
  • Need for additional testing (including referral for invasive testing)
  • Clinical decisionmaking and management based on revised risk stratification such as use of guideline-directed medical therapy, including management of lipids, blood pressure and diabetes; counseling related to diet, physical activity, smoking cessation, alcohol use, and management of psychological factors; use of additional therapies to reduce risk of MI and death (e.g., antiplatelet therapy)
  • Any need for subsequent revascularization (PCI or CABG)
Harms, risks and consequences of testing (both initial and subsequent testing):
  • Harms of testing (renal failure, allergy, nephrogenic systemic fibrosis, contrast-related harms, adverse reaction to medications used for stress testing), vascular complications
  • Risks and consequences (radiation exposure, psychological consequences of diagnosis, need for additional testing)
  • Studies focused on “per-vessel” or “per-segment” analysis without per patient findings
  • Treatments and outcomes of treatments will not be evaluated
Timing At time of first noninvasive test for evaluation (other than initial resting ECG)
Settings Non-emergent inpatient settings, or ambulatory/ outpatient settings, including emergency department
Study Design
  • High quality systematic reviews with or without meta-analysis
  • Prospective studies (RCT or observational) directly comparing interventions with comparators based on established diagnostic criteria will be sought. Retrospective studies will be considered if there are insufficient prospective studies and they are at low risk of bias.
  • Studies of prognosis and decision making will be included if testing results are reported in relation to clinical outcomes and if there is control for confounding as appropriate; studies of predictive accuracy will be considered if they provide clinical outcomes in untreated people.
  • Studies of technique or feasibility or reporting only on the technical aspects of testing
  • Studies exploring prediction models for diagnostic criteria or prognosis
  • Studies comparing pharmacological agents for stress testing with each other
  • Studies of serial assessment of one test
  • Studies with ≤20 patients
  • Non-systematic reviews
  • Narrative reviews
  • Abstracts, editorials, letters, conference proceedings
  • White papers
  • Articles identified as preliminary reports when results are published in later versions
  • Case series, case reports
Publication Type
  • Studies published in English in scholarly journals, published health technology assessments, or publicly available FDA reports
  • Gray literature (e.g., ongoing or unpublished clinical trial data)
  • Single site reports from multicenter trials
  • Duplicate publications of the same study that do not report on unique outcomes or time points

Analytic Framework

Figure 2. Analytic framework for noninvasive testing for coronary artery disease

This figure, referred to as the analytical framework, depicts the Key Questions addressed in this review. In general, the figure illustrates the diagnostic and treatment course and the outcomes for each for a person presenting with symptoms of coronary artery disease (CAD) at either very low, low, or intermediate to high risk for CAD. For example, a patient (far left of diagram) who presents with symptoms suspicious for CAD may receive anatomic or functional testing. The testing may lead to a diagnosis of CAD or further risk stratification,which in turn impacts intermediate outcomes such as the need for additional testing or management options and ultimately the primary health outcomes (far right of the diagram). Harms that may result from either the initial test or subsequent testing are also represented (bottom of diagram) and may include procedural harms as well as the consequences and risks associated with diagnostic testing. The solid lines marked with Key Question numbers are those that this review will evaluate in a comparative way (diagnostic test versus diagnostic test). Key Questions 1-6e (differential efficacy and/or safety) are represented by a footnote (under diagram). The faded text represents the evidence of a relationship between intermediate outcomes and primary health outcomes and adverse events and is beyond the scope of this review.

a People at very low or low risk will be evaluated separately from those at intermediate to high risk as possible.
b KQ 1–6e: Potential modifiers related to differential efficacy and/or safety include patient factors (e.g., age, sex), comorbidities, and ability to exercise.
BP = blood pressure; CABG = coronary artery bypass graft; CAD = coronary artery disease; DM = diabetes mellitus; KQ = Key Question; PCI = percutaneous coronary intervention.

Methods

Input from the Technical Expert Panel (TEP) affirmed that a focus on the associations between testing and clinical outcomes would be of primary interest but there is still a need to provide some information on traditional test parameters as a foundation. Thus, to set the stage for the review’s Key Questions, which are focused on clinical decisionmaking and clinical outcomes, contextual information on the following relevant topics of will be provided in the background of the report.

  • Description of how pre-test probability/risk of CAD is determined based on the triad of patient presentation and physical exam, family history of CAD, and findings on resting ECG in usual clinical practice
  • The ability of ICA to predict primary clinical health outcomes (e.g., avoiding myocardial infarction)
  • Brief discussion of limitations of ICA (thresholds, reliability, etc.) as a reference standard
  • Brief summary of the diagnostic accuracy, in terms of traditional test performance measures (e.g., sensitivity, specificity) of each of the following noninvasive tests based on the highest quality systematic reviews available in symptomatic patients with suspected CAD compared with the historical gold standard of ICA, for the tests listed below. (As ICA with FFR is generally used in people with known CAD, where there is literature using it as a referent in the population of interest it will also be described.)
    • Anatomic tests: coronary calcium scoring via EBCT or MDCT, and CCTA
    • Functional tests (including exercise, vasodilator, and/or dobutamine as stressor where appropriate): exercise electrocardiogram without imaging, exercise/pharmacologic echocardiography (with or without myocardial echo contrast), exercise/pharmacologic nuclear cardiology studies (including SPECT and PET), CT perfusion
  • Brief summary of the diagnostic accuracy of noninvasive tests compared with each other, in terms of traditional test performance measures (e.g., sensitivity, specificity) of each of the noninvasive tests, based on logical comparisons of tests to each other and with ICA, with or without FFR as appropriate
  • Overview of the perceived role(s) of each of the noninvasive diagnostic tests (e.g., to triage, replace, or add on to another test) including:
    • General characteristics of each test and how they are usually employed in clinical settings.
    • For stress testing, provide an overview of when exercises can or cannot be used and general information regarding differences in these populations
  • An overview of treatment efficacy in people with stable CAD will be provided based on the concept that an ideal test is one that is safe, sensitive, and specific and for which efficacious treatment is available for test-positive people. Information may include brief discussion of testing parameters and results in relationship to clinical decisionmaking and thresholds for considering various treatment options. Information may include how treatment(s) compare with no treatment to provide a foundation for interpreting trials in which treatments are compared and information is provided on the efficacy of specific treatments.

A. Criteria for Inclusion/Exclusion of Studies in the Review

The criteria for inclusion and exclusion of studies for the systematic review will be based on the Key Questions and are described in the previous PICOTS section and Table 1. Below are additional details on the scope of this project:

Study Designs

Systematic reviews will be used if they address a Key Question, include studies that meet the PICOTS as defined above, and are assessed as being at low risk of bias, according to the AMSTAR (A Measurement Tool to Assess Systematic Reviews) quality assessment tool.15,16 If multiple systematic reviews are relevant and low risk of bias, we will focus on the findings from the most recent reviews and evaluate areas of consistency and inconsistency across the reviews.17 If systematic reviews are included, we will update findings with any new primary studies identified in our searches and assess strength of evidence based on the totality of evidence. Randomized controlled trials (RCTs) as well as observational studies will be considered and those included will be critically appraised. Prospective studies directly comparing interventions with comparators based on established diagnostic criteria will be sought. Retrospective studies will be considered if there are insufficient prospective studies and they are at low risk of bias. Studies of prognosis and decisionmaking will be included testing results are reported in relation to clinical outcomes and if there is appropriate control for confounding. Studies of predictive accuracy will be considered if there are inadequate comparative studies and if data following testing are available for untreated people. Studies using standard of care as a comparator will be excluded if components for standard of care are not explicitly delineated or defined.

Non-English Language Studies

We will restrict inclusion to English language articles, given the large volume of literature written in English on this topic. We will keep track of studies not written in English that would otherwise meet inclusion criteria to provide insight regarding possible language bias.

B. Searching for the Evidence: Literature Search Strategies for Identification of Relevant Studies to Answer the Key Questions

Publication Date Range

Searches will be conducted without restriction on publication date.

Literature searches will be updated while the draft report is posted for public comment and peer review to capture any new publications. Literature identified during the updated search will be assessed by following the same process of dual review as all other studies considered for inclusion in the report. If any pertinent new literature is identified for inclusion in the report, it will be incorporated before the final submission of the report.

Literature Databases

Ovid MEDLINE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and International Network of Agencies for Health Technology Assessment’s (INAHTA) Center for Reviews and Dissemination (CRD)-HTA database will be searched to capture both published and gray literature.

Scientific Information Packets

Scientific Information Packets (SIPs) will be solicited by the Scientific Resource Center via the AHRQ Web site and via direct mailings to manufacturers.

Hand Searching

Reference lists of included articles will also be reviewed for includable literature.

Process for Selecting Studies

Pre-established criteria will be used to determine eligibility for inclusion and exclusion of abstracts in accordance with the Agency for Healthcare Research and Quality (AHRQ) Methods Guide for Effectiveness and Comparative Effectiveness Reviews.15 To ensure accuracy, all excluded abstracts will be dual reviewed. All citations deemed appropriate for inclusion by at least one of the reviewers will be retrieved. Each full-text article will be independently reviewed for eligibility by two team members, including any articles suggested by peer reviewers or that arise from the public posting process. Any disagreements will be resolved by consensus.

C. Data Abstraction and Data Management

After studies are selected for inclusion, data will be abstracted into categories that include but are not limited to: study design, year, setting, country, sample size, eligibility criteria, population and clinical characteristics, diagnostic criteria and thresholds, setting and rationale for testing/intended role of the test and results relevant to each part of the Key Question as outlined in the previous PICOTS section. Information relevant for assessing applicability will be abstracted, including the number of patients receiving testing, characteristics of the population (including CAD prevalence, comorbid conditions), factors that may affect test performance (e.g., presence of arrhythmias), and care setting (both the characteristics of the health care organization and practice patterns). All extracted study data will be verified for accuracy and completeness by a second team member. A record of studies excluded at the full-text level with reasons for exclusion will be maintained.

D. Assessment of Methodological Risk of Bias of Individual Studies

Predefined criteria will be used to assess the quality of included studies. We will focus on studies with the least potential for bias and the fewest limitations. We will assess study limitations using instruments designed to address issues particularly relevant to medical testing studies, such as Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) and Standards for Reporting of Diagnostic Accuracy (STARD) and standardized application of such criteria as described in the AHRQ Methods Guide for Medical Test Reviews.18 For studies of prognosis and clinical management, risk of bias assessment will be based on pre-defined criteria using clearly defined templates for the criteria as appropriate, following guidance from the AHRQ Methods Guide for Effectiveness and Comparative Effectiveness Reviews.15 Randomized controlled trials (RCTs) will be assessed based on appropriate criteria and methods established in the Cochrane Handbook for Systematic Reviews of Interventions.19 These criteria and methods will be used in concordance with the approach recommended in the chapter, Assessing the Risk of Bias of Individual Studies When Comparing Medical Interventions.20 Studies will be rated as being “good,” “fair,” or “poor” quality.

Studies rated “good” are considered to have the least risk of bias, and their results are considered valid. Good-quality studies include clear descriptions of the population, setting, interventions, and comparison groups; a valid method for allocation of patients to treatment; low dropout rates and clear reporting of dropouts; appropriate means for preventing bias; and appropriate measurement of outcomes.

Studies rated “fair” are susceptible to some bias, though not enough to invalidate the results. These studies may not meet all the criteria for a rating of good quality, but no flaw is likely to cause major bias. The study may be missing information, making it difficult to assess limitations and potential problems. The fair-quality category is broad, and studies with this rating will vary in their strengths and weaknesses. The results of some fair-quality studies are likely to be valid, while others may be only possibly valid.

Studies rated “poor” have significant flaws that imply biases of various types that may invalidate the results. They have a serious or “fatal” flaw in design, analysis, or reporting; large amounts of missing information; discrepancies in reporting; or serious problems in the delivery of the intervention. The results of these studies are at least as likely to reflect flaws in the study design as the true difference between the compared interventions. Studies rated as being poor in quality a priori were not excluded, but considered to be less reliable than higher quality studies when synthesizing the evidence, particularly if discrepancies between studies are present.

Each study evaluated will be dual-reviewed for quality by two team members. Any disagreements will be resolved by discussion and consensus.

E. Data Synthesis

We will construct evidence tables identifying the study characteristics (as discussed above), results of interest, and quality ratings for all included studies, and summary tables to highlight the main findings. We will review and highlight studies by using a hierarchy-of-evidence approach, where the best evidence is the focus of our synthesis for each key question. Studies with the least risk of bias will be summarized separately and compared with summarized results from poorer quality studies. In general, prospective studies which directly compare tests of interest in an appropriate spectrum of patients using validated diagnostic criteria that provide details regarding measurement of pertinent outcomes as well as consideration of and control for bias and confounding may have the least potential for bias. Retrospective studies will be considered if there is low risk of bias. In the evidence tables, we will include relevant studies from included systematic reviews as appropriate.

The intended focus is on clinical outcomes and clinical pathways following the first test performed as result of initial risk assessment (which includes clinical presentation and physical exam, family history of CAD and findings on resting ECG). Harms related to subsequent testing will be evaluated. The specific tests to be covered will be restricted to those identified as widely available and most clinically applicable and established. We will focus on “decision-relevant” outcomes, including the consequences of testing and impact on clinical outcomes such as myocardial infarction and need for revascularization. Consequences of testing may also include use of downstream testing, anxiety related to false positives, and incidental findings. Decision diagrams may facilitate conceptualization of this and augment the current analytic framework. Heterogeneity in study quality is expected and evaluation of the influence of bias will be considered. The categories of very low and low risk of CAD will be combined and analyzed separately from those at intermediate to high CAD risk.

Data will be qualitatively summarized in summary tables or figures. Interpretation of the results will be provided descriptively.

Meta-analyses will be conducted to summarize data and obtain more precise estimates on outcomes for which studies are homogeneous enough to provide a meaningful combined estimate. The feasibility of a quantitative synthesis will depend on the number and completeness of reported outcomes and a lack of heterogeneity among the reported results. To determine whether meta-analysis could be meaningfully performed, we will consider the quality of the studies and the heterogeneity among studies in design, patient population, interventions, and outcomes, and may conduct sensitivity analyses. The key questions are designed to assess the comparative effectiveness and harms of various noninvasive tests for coronary artery disease. Meta-regression may be conducted to explore statistical heterogeneity using additional variables on methodological or other characteristics (e.g., quality factors, diagnostic thresholds or criteria, outcome definitions and ascertainment) if there are sufficient numbers of studies.

Results will be presented as structured by the key questions, and any prioritized outcomes will be presented first.

F. Grading the Strength of Evidence (SOE) for Individual Comparisons and Outcomes

The strength of evidence for each key question will be initially assessed by one researcher for each clinical outcome (see PICOTS) by following the principles for adapting GRADE (Grading of Recommendations Assessment, Development and Evaluation) outlined in the AHRQ medical testing methods guide.18 In determining the strength of a body of evidence regarding a given outcome, the following domains are considered:

  • Risk of bias: the extent to which studies reporting on a particular outcome are likely to be protected from bias; graded as low, medium, or high risk of bias)
  • Consistency: the extent to which studies report the same direction of effect for a particular outcome; graded as consistent, inconsistent, or unknown (in the case of a single study)
  • Directness: reflects whether the outcome is directly or indirectly related to health outcomes of interest; graded as direct or indirect.
  • Precision: describes the level of certainty of the estimate of effect for a particular outcome with a precise estimate being on that allows a clinically useful conclusion; graded as precise or imprecise
  • Publication bias: indicates that studies may have been published selectively based on consideration of the extent to which relevant empirical findings (e.g., negative or no-difference findings) have not been published or are not available. This is difficult to assess for reviews of diagnostic testing and statistical methods of assessing this may be misleading.18,21 Clinical trial registries will be searched for unpublished studies and information from SIPs will be evaluated; graded as suspected or undetected.

Briefly, bodies of evidence consisting of RCTs are initially considered as high strength while bodies of comparative observational studies begin as low strength evidence. The strength of the evidence may be downgraded based on the limitations described above. There are also situations where the observational evidence may be upgraded (e.g., large magnitude of effect, presence of dose-response relationship or existence of plausible unmeasured confounders) as described in the AHRQ methods guides.15,18

A final strength of evidence grade will be assigned by evaluating and weighing the combined results of the above domains. To ensure consistency and validity of the evaluation, the grades will be reviewed by the entire team of investigators. The strength of evidence will be assigned an overall grade of high, moderate, low, or insufficient according to a four-level scale.

  • High—We are very confident that the estimate of effect lies close to the true effect for this outcome. The body of evidence has few or no deficiencies. We believe that the findings are stable, i.e., another study would not change the conclusions.
  • Moderate—We are moderately confident that the estimate of effect lies close to the true effect for this outcome. The body of evidence has some deficiencies. We believe that the findings are likely to be stable, but some doubt remains.
  • Low—We have limited confidence that the estimate of effect lies close to the true effect for this outcome. The body of evidence has major or numerous deficiencies (or both). We believe that additional evidence is needed before concluding either that the findings are stable or that the estimate of effect is close to the true effect.
  • Insufficient—We have no evidence, we are unable to estimate an effect, or we have no confidence in the estimate of effect for this outcome. No evidence is available or the body of evidence has unacceptable deficiencies, precluding reaching a conclusion.

G. Assessing Applicability

Applicability will be estimated by examining the characteristics of the patient populations (e.g., demographic characteristics such as age, sex, comorbidities); the sample size of the studies; and clinical settings (e.g., academic setting, provider experience) in which the studies are performed. Variability in the studies may limit the ability to generalize the results to other populations and settings.

References

  1. Ruigomez A, Rodriguez LA, Wallander MA, et al. Chest pain in general practice: incidence, comorbidity and mortality. Fam Pract. 2006;23(2):167-74.
  2. Go AS, Mozaffarian D, Roger VL, et al. Heart disease and stroke statistics--2013 update: a report from the American Heart Association. Circulation. 2013;127(1):e6-e245.
  3. Lozano R, Naghavi M, Foreman K, et al. Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. 2012;380(9859):2095-128.
  4. Heidenreich PA, Trogdon JG, Khavjou OA, et al. Forecasting the future of cardiovascular disease in the United States: a policy statement from the American Heart Association. Circulation. 2011;123(8):933-44.
  5. Detry JM. The pathophysiology of myocardial ischaemia. Eur Heart J. 1996 Dec;17 Suppl G:48-52. PMID: 8960456.
  6. Schoen F. Chapter 13, The Heart. In: Cotran RS KV, Collins T, ed Robbins Pathophysiologic Basis of Disease. sixth ed. Philadelphia, London, Toronto, Montreal, Sydney, Tokyo: W. B. Saunders Company; 1999:543-99.
  7. Lloyd-Jones D, Adams RJ, Brown TM, et al. Heart disease and stroke statistics--2010 update: a report from the American Heart Association. Circulation. 2010 Feb 23;121(7):e46-e215. PMID: 20019324.
  8. Fihn SD, Gardin JM, Abrams J, et al. 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the diagnosis and management of patients with stable ischemic heart disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, and the American College of Physicians, American Association for Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol. 2012;60(24):e44-e164.
  9. Fuster V. 50th anniversary historical article. Acute coronary syndromes: the degree and morphology of coronary stenoses. J Am Coll Cardiol. 1999;34(7):1854-6.
  10. Topol EJ, Nissen SE. Our preoccupation with coronary luminology. The dissociation between clinical and angiographic findings in ischemic heart disease. Circulation. 1995;92(8):2333-42.
  11. Zir LM, Miller SW, Dinsmore RE, et al. Interobserver variability in coronary angiography. Circulation. 1976;53(4):627-32.
  12. Tavakol M, Ashraf S, Brener SJ. Risks and complications of coronary angiography: a comprehensive review. Global journal of health science. 2012 Jan;4(1):65-93. PMID: 22980117.
  13. Patel MR, Dehmer GJ, Hirshfeld JW, et al. ACCF/SCAI/STS/AATS/AHA/ASNC/HFSA/SCCT 2012 Appropriate use criteria for coronary revascularization focused update: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, Society for Cardiovascular Angiography and Interventions, Society of Thoracic Surgeons, American Association for Thoracic Surgery, American Heart Association, American Society of Nuclear Cardiology, and the Society of Cardiovascular Computed Tomography. J Am Coll Cardiol. 2012 Feb 28;59(9):857-81. PMID: 22296741.
  14. Shaw LJ, Berman DS, Picard MH, et al. Comparative definitions for moderate-severe ischemia in stress nuclear, echocardiography, and magnetic resonance imaging. JACC. Cardiovascular imaging. 2014 Jun;7(6):593-604. PMID: 24925328.
  15. Methods Guide for Effectiveness and Comparative Effectiveness Reviews. AHRQ Publication No. 10(14)-EHC063-EF. Rockville, MD: Agency for Healthcare Research and Quality. January 2014. Chapters available at: www.effectivehealthcare.ahrq.gov.
  16. Shea BJ, Hamel C, Wells GA, et al. AMSTAR is a reliable and valid measurement tool to assess the methodological quality of systematic reviews. Journal of clinical epidemiology. 2009 Oct;62(10):1013-20. PMID: 19230606.
  17. White CM, Ip S, McPheeters M, et al. AHRQ Methods for Effective Health Care Using Existing Systematic Reviews To Replace De Novo Processes in Conducting Comparative Effectiveness Reviews. Methods Guide for Effectiveness and Comparative Effectiveness Reviews. Rockville (MD): Agency for Healthcare Research and Quality (US); 2008.
  18. Methods Guide for Medical Test Reviews. AHRQ Publication No. 12-EC017. Rockville, MD: Agency for Healthcare Research and Quality; June 2012. www.effectivehealthcare.ahrq.gov/reports/final.cfm. Also published as a special supplement to the Journal of General Internal Medicine, July 2012.
  19. Higgins JPT GS, ed Cochrane Handbook for Systematic Reviews of Interventions. Version 5.1.0. ed; 2011.
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  22. Amsterdam EA, Wenger NK, Brindis RG, et al. 2014 AHA/ACC Guideline for the Management of Patients With Non-ST-Elevation Acute Coronary Syndromes: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2014 Sep 18PMID: 25260717.

Definition of Terms

Acute Coronary Syndrome (ACS)
A condition in which a coronary artery becomes blocked by plaque and blood flow to the heart is diminished. In some cases, the plaque may rupture and create a blood clot; this combination of plaque and blood clot may lead to myocardial infarction (a heart attack). ACS refers to a spectrum of clinical presentations ranging from those for ST-segment elevation myocardial infarction (STEMI) to those found in non-ST segment elevation myocardial infarction (NSTEMI).

Atheromatous plaque
An accumulation of fibrous tissues, lipids, and macrophage cells within the artery walls that narrows the artery and restricts blood flow.

Computed tomography (CT) with fractional flow reserve (FFR)
In order to estimate coronary blood flow, mathematical models are applied to data from a CT scan. This has been developed as an alternative to invasive FFR measurement in which a pressure wire is placed in the artery.

Computed tomography (CT) perfusion
Dye is injected into a person’s vein and then an X-ray and computer are used to create 3D (three-dimensional) pictures of the heart and arteries to evaluate blood flow and/or damage to the muscle.

Coronary calcium scoring via EBCT (electron beam CT) or MDCT (multidetector CT)
Utilizes X-rays, without the use of intravenous contrast dye, to look for calcium deposits (calcifications) within the coronary arteries that may be obstructing the pathway; the degree and extent of calcification is expressed as a calcium score.

Coronary CT angiography (CCTA)
Utilizes X-rays and contrast dye to produce 3D images of the heart and arteries. CCTA is able to image blockages and narrowing of the arteries without the use of a catheter.

Coronary magnetic resonance angiography (MRA)
Utilizes magnetic fields and pulses or radio wave energy rather than X-rays to view blood vessels. Calcifications, plaque buildup, blood vessel narrowing, and tearing of a vessel are all visible with this imaging technique. May be performed with or without a contrast dye.

Exercise electrocardiogram (ECG) without imaging
A person walks on a treadmill or pedals a stationary bike in order to elevate their heart rate while an ECG records the electrical activity of the heart. Blood pressure and breathing are monitored as well.

Exercise/pharmacologic echocardiography (with or without myocardial echo contrast)
A person’s heart is stressed either through exercise or the use of drugs that increase the heart rate and an ultrasound is used to create an image of the heart that is used to evaluate cardiac function and identify any structural abnormalities of the heart.

Guideline-Directed Medical Therapy (GDMT)
Term used to represent medical therapy that is strongly recommended by (primarily Class I and IIa) ACC/AHA guidelines.8

Non-ST-Elevation Acute Coronary Syndromes (NSTE-ACS)
This term has been adopted by the American College of Cardiology and the American Heart Association as it “emphasizes the continuum between unstable angina and NSTEMI”.22

Non-ST-segment elevation myocardial infarction (NSTEMI)
Also called a heart attack and is caused by a partial or temporary blockage, resulting in relatively minimal damage to the heart muscle; it does not cause changes on an ECG but can be demonstrated by an elevation of cardiac biomarkers in the blood.

Pharmacologic stress magnetic resonance imaging (MRI)
Drugs are used to stress the heart and then an MRI, which uses magnets, radiofrequencies and a computer, produces images of the heart and arteries. Contrast may also be used to map the flow of blood.

Positron emission tomography (PET)
A radioactive component is injected into the patient and the uptake and decay of the compound are used to create images of the coronary arteries and the heart and provide information on blood flow. PET and SPECT are similar, but PET provides a higher level of resolution than SPECT.

Predictive accuracy studies
Studies of predictive accuracy use test result information to identify people who will have a future event, such as myocardial infarction. Such studies identify patients who benefit from treatment and those do not; may also be referred to as prognostic accuracy.

Serum cardiac biomarkers
Blood serum is made through the process of coagulation to remove blood cells and clotting proteins in order to isolate other proteins like kinases and troponins. This protein-containing serum may then be used to evaluate heart function and aid in diagnosis of a cardiac disorder.

Single photon emission computed tomography (SPECT)
A radioactive component is injected into a person and a gamma camera records emissions of the radiation in a series of 2D images from different angles that are combined to create a 3D view.

ST-segment elevation myocardial infarction (STEMI)
Also called a heart attack and caused by a complete blockage of the coronary artery resulting in a prolonged period of ischemia; it affects a large area of the heart muscle and thus causes changes on an ECG as well as in the serum cardiac biomarkers.

T-wave (ECG change)
When the heart’s ventricles become repolarized, this appears on an ECG as the T-wave. Inversion or change in amplitude or symmetry of the T-wave may be an indication of cardiac dysfunction.

Summary of Protocol Amendments

Summary of Protocol Amendments
Date Amendment Rationale
12/18/2014 Exclusion of CT Perfusion. Revisions were made to the Background, the PICOTS, and the Methods sections to reflect this change. Based on review by internal experts and consultation with the TEP, CT perfusion was excluded as it does not fit within the focus of the review on widely available, established/accepted tests which may commonly be used as a first test (aside from resting ECG) for diagnosis of CAD in the population of interest. While it is available from the perspective that it requires no additional hardware or software to do it in a rudimentary fashion, it is not well validated, requires an extra scan (with a vasodilator), more contrast and radiation, it is not currently used outside of the research setting.
12/18/2014 Remove reference to coronary magnetic resonance angiography (MRA) from the Background. To avoid confusion for readers, reference to MRA in the background was removed. MRA is not an included test for this review as it is an experimental technique and not well established for the diagnosis of CAD.
12/18/2014 Add the following sentence under Clinical Outcomes (primary focus) in the PICOTS section: “For studies of predictive accuracy that do not compare two tests, only the following hard clinical outcomes will be evaluated: MI, heart failure, death; other outcomes listed above will be evaluated based on studies comparing two or more tests” Enhanced clarification regarding inclusion of predictive accuracy studies that do not compare two tests but may compare those who test positive and are treated with those who test negative and are not treated. For these studies, only the following hard clinical outcomes will be evaluated: MI, heart failure, death. Comparative studies (i.e., those comparing two tests) will be used to evaluate other primary outcomes.
12/18/2014 Add the following sentence under Intermediate Outcomes in the PICOTS section: “to be evaluated based on comparative studies only” Enhanced clarification. Only comparative studies (i.e., those comparing two tests) will be used to evaluate intermediate outcomes.

Review of Key Questions

Key questions were reviewed and refined as needed by the Evidence-based Practice Center (EPC) with input from the AHRQ Task Order Officer (TOO) to ensure that the questions are specific and explicit about what information is being reviewed. AHRQ posted the provisional key questions on the Effective Health Care Website for public comment. The EPC refined the key questions after review of the public comments, and input from Key Informants. This input is intended to ensure that the key questions are specific and relevant.

Key Informants

Key informants are the end users of research, including patients and caregivers, practicing clinicians, relevant professional and consumer organizations, purchasers of health care, and others with experience in making health care decisions. Within the EPC program, the key informant role is to provide input into identifying the Key Questions for research that will inform healthcare decisions. The EPC solicits input from key informants when developing questions for systematic review or when identifying high priority research gaps and needed new research. Key informants are not involved in analyzing the evidence or writing the report and have not reviewed the report, except as given the opportunity to do so through the peer or public review mechanism.

Key informants must disclose any financial conflicts of interest greater than $10,000 and any other relevant business or professional conflicts of interest. Because of their role as end-users, individuals are invited to serve as key informants and those who present with potential conflicts may be retained. The TOO and the EPC work to balance, manage, or mitigate any potential conflicts of interest identified.

Technical Expert Panel

A multi-disciplinary group of clinical, content, and methodologic experts will provide input in further defining populations, interventions, comparisons, or outcomes as well as identifying particular studies or databases to search. They will provide broad expertise and perspectives specific to the topic under development. Divergent and conflicted opinions are common and perceived as health scientific discourse that results in a thoughtful, relevant systematic review. Therefore study questions, design and/or methodological approaches do not necessarily represent the views of individual technical and content experts. Technical experts will provide information to the EPC to identify literature search strategies and recommend approaches to specific issues as requested by the EPC. Technical experts do not do analysis of any kind nor contribute to the writing of the report and have not reviewed the report, except as given the opportunity to do so through the peer or public review mechanism.

Technical experts must disclose any financial conflicts of interest greater than $10,000 and any other relevant business or professional conflicts of interest. Because of their unique clinical or content expertise, individuals are invited to serve as technical experts and those who present with potential conflicts may be retained. The TOO and the EPC work to balance, manage, or mitigate any potential conflicts of interest identified.

Peer Reviewers

Peer reviewers are invited to provide written comments on the draft report based on their clinical, content, or methodologic expertise. Peer review comments on the preliminary draft of the report are considered by the EPC in preparation of the final draft of the report. Peer reviewers do not participate in writing or editing of the final report or other products. The synthesis of the scientific literature presented in the final report does not necessarily represent the views of individual reviewers. The dispositions of the peer review comments are documented and will, for Comparative Effectiveness Reviews and Technical briefs, be published three months after the publication of the Evidence report.

Potential reviewers must disclose any financial conflicts of interest greater than $10,000 and any other relevant business or professional conflicts of interest. Invited peer reviewers may not have any financial conflict of interest greater than $10,000. Peer reviewers who disclose potential business or professional conflicts of interest may submit comments on draft reports through the public comment mechanism.

EPC Team Disclosures

EPC core team members must disclose any financial conflicts of interest greater than $1,000 and any other relevant business or professional conflicts of interest. Related financial conflicts of interest which cumulatively total greater than $1,000 will usually disqualify EPC core team investigators.

Role of the Funder

This project was funded under Contract No. HHSA 290-2012-00014-I from the Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services. The Task Order Officer reviewed contract deliverables for adherence to contract requirements and quality. The authors of this report are responsible for its content. Statements in the report should not be construed as endorsement by the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.