Special Medical Reports
ACC/AHA Panel Prepares Guidelines for Exercise Testing
Am Fam Physician. 1998 Feb 1;57(3):563-565.
The American College of Cardiology/American Heart Association (ACC/AHA) Task Force on Practice Guidelines has developed guidelines for cardiovascular exercise testing. The entire guidelines are published in the July 1997 issue of the Journal of the American College of Cardiology, and the executive summary is published in the July 1, 1997, issue of Circulation. The guidelines and executive summary are available from ACC (telephone: 800-253-4636, ext. 694) or from AHA (telephone: 800-242-8721). Copies of all ACC/AHA guidelines are available on the World Wide Web (http://www.acc.org and http://www.amhrt.org).
The guidelines cover the use of exercise testing in the diagnosis of obstructive coronary artery disease (CAD), in risk assessment and prognosis in patients with symptoms or a previous history of CAD and in the evaluation of patients following a myocardial infarction. In addition, there are sections on exercise testing using ventilatory gas analysis and the use of exercise testing in women, in the elderly, in asymptomatic persons, in patients following revascularization procedures and in children.
The ACC/AHA recommendations are constructed on the basis of the ACC/AHA method of classification used in developing guidelines. A list of the different classifications and their definitions is in the table below. The following summarizes the recommendations for exercise testing in different clinical settings, based on the ACC/AHA classifications I, II and III.
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ACC/AHA Classifications Used to Summarize Indications for Exercise Testing
Class I—Conditions for which there is evidence and/or general agreement that a given procedure or treatment is useful and effective.
Class II—Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness/efficacy of a procedure or treatment.
Class IIa—Weight of evidence/opinion in favor of usefulness/efficacy.
Class IIb—Usefulness/efficacy is less well established by evidence/opinion
Class III—Conditions for which there is evidence and/or general agreement that the procedure/treatment is not useful/effective and in some cases may be harmful.
Diagnosis of Obstructive CAD
Class I
Adult patients (including those with complete right bundle branch block or less than 1 mm of resting ST-segment depression) with an intermediate pretest probability of CAD, based on gender, age and symptoms.
Class IIa
Patients with vasospastic angina.
Class IIb
Patients with a high pretest probability of CAD by age, symptoms and gender.
Patients with a low pretest probability of CAD by age, symptoms and gender.
Patients with less than 1 mm of baseline ST depression and taking digoxin.
Patients with electrocardiographic (ECG) criteria for left ventricular hypertrophy and less than 1 mm of baseline ST depression.
Patients with one of the following baseline electrocardiographic abnormalities: preexcitation syndrome, electronically paced ventricular rhythm, greater than 1 mm of resting ST depression, or complete left bundle branch block.
Patients with a documented myocardial infarction or prior coronary angiography demonstrating significant disease have an established diagnosis of CAD; however, ischemia and risk can be determined by testing.
The recommendations state that the most important clinical finding in the diagnosis of CAD is a history of chest discomfort or pain. Diagnostic testing is most valuable in patients with an intermediate pretest probability of CAD.
Meta-analysis of 58 consecutively published studies, involving 11,691 patients, indicates a wide variability in the sensitivity and specificity of exercise testing for the diagnosis of CAD, underscoring the importance of using proper methods for testing and analysis. Upsloping ST-segment depression should be considered a borderline or negative finding. Although specificity is lowered somewhat by a resting ST depression of less than 1 mm, exercise testing is still the first option in the evaluation of possible CAD in such patients with an intermediate pretest probability. Specificity is also lowered by left ventricular hypertrophy with less than 1 mm of ST depression and the use of digoxin with less than 1 mm of ST depression, but the standard exercise test is still a reasonable option in such patients.
Risk Assessment and Prognosis in Patients with Symptoms or a History of CAD
Patients undergoing initial evaluation with suspected or known CAD. Specific exceptions are noted below in Class IIb.
Patients with suspected or known CAD who were previously evaluated but have a significant change in clinical status.
Patients with one of the following ECG abnormalities: preexcitation syndrome, electronically paced ventricular rhythm, greater than 1 mm of resting ST depression, or complete left bundle branch block.
Patients with a stable clinical course who undergo periodic monitoring to guide treatment.
Patients with severe comorbidity likely to limit life expectancy and/or candidacy for revascularization.
Unless cardiac catheterization is indicated, patients with suspected or known CAD and new or changing symptoms that suggest ischemia should generally undergo exercise testing to assess the risk of future cardiac events. The choice of the initial stress test modality should be based on an evaluation of the patient's resting ECG and physical ability to exercise and on local expertise and technology.
Exercise testing may be useful for prognostic assessment of patients receiving digoxin therapy or patients with an abnormal resting ECG, but its usefulness is less well established in this setting.
After Myocardial Infarction
Before discharge for prognostic assessment, activity prescription or evaluation of medical therapy (submaximal at about four to seven days). Exceptions are noted in classes IIb and III.
Early after discharge for prognostic assessment, activity prescription, evaluation of medical therapy and cardiac rehabilitation if the predischarge exercise test was not done (symptom-limited, about 14 to 21 days). Exceptions are noted in classes IIb and III.
Late after discharge for prognostic assessment, activity prescription evaluation of medical therapy, and cardiac rehabilitation if the early exercise test was submaximal (symptom-limited, about three to six weeks). Exceptions are noted in classes IIb and III.
After discharge for activity counseling and/or exercise training as part of cardiac rehabilitation in patients who have undergone coronary revascularization.
Before discharge in patients who have undergone cardiac catheterization to identify ischemia in the distribution of the coronary lesion of borderline severity.
Patients with one of the following ECG abnormalities: complete left bundle branch block, preexcitation syndrome, left ventricular hypertrophy, digoxin therapy, greater than 1 mm of resting ST-segment depression or electronically paced ventricular rhythm.
Periodic monitoring in patients who continue to participate in exercise training or cardiac rehabilitation.
Severe comorbidity likely to limit life expectancy and/or candidacy for revascularization.
Symptomatic ischemic ST-segment depression on exercise testing after thrombolytic therapy increases the risk of cardiac mortality twofold, but the absolute risk remains low (1.7 percent at six months). There is limited evidence regarding the ability of exercise testing to risk-stratify patients who have not received reperfusion therapy.
Asymptomatic Persons Without Known CAD
Evaluation of persons with multiple risk factors.
Evaluation of asymptomatic men older than 40 years and women older than 50 years who plan to start vigorous exercise (especially if sedentary), who are involved in occupations in which impairment might have an impact on public safety, or who are at high risk for CAD due to other diseases (e.g., chronic renal failure).
Routine screening of asymptomatic men or women.
General population screening programs to identify young patients with early disease are limited because severe CAD that requires intervention in asymptomatic patients is exceedingly rare. Although the physical risks of exercise testing are negligible, false-positive test results may engender inappropriate anxiety and may have serious adverse consequences related to work and insurance coverage. For these reasons, exercise testing in healthy, asymptomatic persons is not recommended. However, screening may be potentially helpful in patients who are at least at moderate risk of CAD.
Evaluation of exercise capacity of patients with valvular heart disease.
Diagnosis of CAD in patients with valvular heart disease.
Before and After Revascularization
Demonstration of proof of ischemia before revascularization.
Evaluation of patients with recurrent symptoms suggesting ischemia after revascularization.
Detection of restenosis in selected, high-risk asymptomatic patients within the first months after angioplasty.
Periodic monitoring of selected, high-risk asymptomatic patients for restenosis, graft occlusion or disease progression.
Localization of ischemia for determining the site of intervention.
Routine, periodic monitoring of asymptomatic patients after percutaneous transluminal coronary angioplasty or coronary artery bypass grafting without specific indications.
Investigation of Heart Rhythm Disorders
Identification of appropriate settings in patients with rate-adaptive pacemakers.
Evaluation of patients with known or suspected exercise-induced arrhythmias.
Evaluation of medical, surgical or ablative therapy in patients with exercise-induced arrhythmias (including atrial fibrillation).
Investigation of isolated ventricular ectopic beats in middle-aged patients without other evidence of CAD.
Investigation of isolated ectopic beats in young patients.
Exercise Testing in Women
The guidelines state that the accuracy of exercise ECG for the diagnosis of CAD in women is problematic. Exercise-induced ST depression is less sensitive in women than in men, reflecting a lower prevalence of severe CAD and the inability of many women to exercise to maximum aerobic capacity. Physicians should be cognizant of the decreased sensitivity that occurs when women do not exercise to maximum aerobic capacity. Patients likely to exercise submaximally should undergo pharmacologic stress testing.
The difficulties posed by clinical evaluation of women for possible CAD have led to speculation that stress imaging may be an efficient initial alternative to exercise tests. Although the optimal strategy for circumventing false-positive test results for the diagnosis of CAD in women remains to be defined, the data are insufficient to justify routine stess imaging tests as the initial test for the diagnosis of CAD in women.
SHARON SCOTT MOREY
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