Exercise Testing

Abstract

Patients with known or suspected coronary artery disease often undergo exercise stress testing to either diagnose coronary artery disease or to determine functional status or prognosis. Frequently, though, more advanced imaging techniques are combined with the exercise ECG portion and the information obtained from the exercise ECG test is underappreciated. In this chapter, we review the current indications and contraindications of exercise ECG testing, as well as interpretations of exercise ECG testing. We also review how the exercise ECG can aid in the diagnosis of coronary artery disease, and the prognostic implications of a normal or abnormal test result. Finally, as the economic landscape of medicine rapidly changes and more emphasis is being placed on cost-saving, we discuss the cost-effectiveness of exercise ECG testing compared to more advanced stress imaging protocols.

Appendix 1

The ACC/AHA Classifications I, II, and III Used to Summarize Indications

• 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 is 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.

Exercise Testing to Diagnose Obstructive Coronary Artery Disease

• Class I: Adult patients (including those with complete right bundle-branch block or less than 1 mm or resting ST depression) with an intermediate pretest probability of CAD on the basis of gender, age, and symptoms (specific exceptions are noted under Classes II and III below).

• Class IIa: Patients with vasospastic angina.

• Class IIb:

  • 1. Patients with a high pretest probability of CAD by age, symptoms, and gender.

  • 2. Patients with a low pretest probability of CAD by age, symptoms, and gender.

  • 3. Patients with <1 mm of baseline ST depression and taking digoxin.

  • 4. Patients with electrocardiographic criteria for left ventricular hypertrophy (LVH) and <1 mm of baseline ST depression.

• Class III:

  • 1. Patients with the following baseline ECG abnormalities:

    • Pre-excitation (Wolff-Parkinson-White) syndrome

    • Electronically paced ventricular rhythm

    • >1 mm of resting ST depression

    • Complete left bundle branch block

  • 2. 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 (see sections III and IV).

Risk Assessment and Prognosis in Patients with Symptoms or a Prior History of CAD

• Class I:

  • 1. Patients undergoing initial evaluation with suspected or known CAD including those with complete right bundle-branch block or <1 mm of resting ST depression. Specific exceptions are noted below in Class IIb

  • 2. Patients with suspected or known CAD, previously evaluated, presenting with significant change in clinical status.

  • 3. Low-risk unstable angina patients 8–12 h after presentation who have been free of active ischemic or heart failure symptoms (Level of Evidence: B).

  • 4. Intermediate-risk unstable angina patients 203 days after presentation who have been free of active ischemic or heart failure symptoms (Level of Evidence: B)

• Class IIa: Intermediate-risk unstable angina patients who have initial cardiac markers that are normal, a repeat ECG without significant change, and cardiac markers 6–12 h after the onset of symptoms that are normal and no other evidence of ischemia during observation (Level of Evidence: B).

• Class IIb:

  • 1. Patients with the following resting ECG abnormalities:

    • Pre-excitation (Wolff-Parkinson-White) syndrome

    • Electronically paced ventricular rhythm

    • 1 mm or more of resting ST depression

    • Complete left bundle-branch block or any interventricular conduction defect with a QRS duration >120 ms

  • 2. Patients with a stable clinical course who undergo periodic monitoring to guide treatment.

• Class III:

  • 1. Patients with severe comorbidity likely to limit life expectancy and/or candidacy for revascularization.

  • 2. High-risk unstable angina patients (Level of Evidence: C).

After Myocardial Infarction

• Class I:

  • 1. Before discharge for prognostic assessment, activity prescription, evaluation of medical therapy (submaximal at about 4–6 days).*

  • 2. Early after discharge for prognostic assessment, activity prescription, evaluation of medical therapy, and cardiac rehabilitation if the predischarge exercise test was not done (symptoms limited; about 14–21 days).*

  • 3. 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 3–6 weeks).*

• Class IIa: After discharge for activity counseling and/or exercise training as part of cardiac rehabilitation in patients who have undergone coronary revascularization.

• Class IIb:

  • 1. Patients with the following ECG abnormalities:

    • Complete left bundle-branch block

    • Pre-excitation syndrome

    • LVH

    • Digoxin therapy

    • >1 mm of resting ST-segment depression

    • Electronically paced ventricular rhythm

  • 2. Periodic monitoring in patients who continue to participate in exercise training or cardiac rehabilitation.

• Class III:

  • 1. Severe comorbidity likely to limit life expectancy and/or candidacy for revascularization.

  • 2. At any time to evaluate patients with acute myocardial infarction who have uncompensated congestive heart failure, cardiac arrhythmia, or noncardiac conditions that severely limit their ability to exercise (Level of Evidence: C).

  • 3. Before discharge to evaluate patients who have already been selected for, or have undergone, cardiac catheterization. Although a stress test may be useful before or after catheterization to evaluate or identify ischemia in the distribution of a coronary lesion of borderline severity, stress imaging tests are recommended (Level of Evidence: C).

    *Exceptions are noted under Classes IIb and III.

Exercise Testing with Ventilatory Gas Analysis

• Class I:

  • 1. Evaluation of exercise capacity and response to therapy in patients with heart failure who are being considered for heart transplantation.

  • 2. Assistance in the differentiation of cardiac versus pulmonary limitations as a cause of exercise-induced dyspnea or impaired exercise capacity when the cause is uncertain.

• Class IIa: Evaluation of exercise capacity when indicated for medical reasons in patients in whom the estimates of exercise capacity from exercise test time or work rate are unreliable.

• Class IIb:

  • 1. Evaluation of the patient’s response to specific therapeutic interventions in which improvement of exercise tolerance is an important goal or end point.

  • 2. Determination of the intensity for exercise training as part of comprehensive cardiac rehabilitation.

• Class III: Routine use to evaluate exercise capacity.

Special Groups: Women, Asymptomatic Individuals, and Post Revascularization Patients

Exercise Testing in Asymptomatic Persons Without Known CAD

• Class I: None

• Class IIa: Evaluation of asymptomatic persons with diabetes mellitus who plan to start vigorous exercise (Level of Evidence: C).

• Class IIb:

  • 1. Evaluation of persons with multiple risk factors as a guide to risk- reduction therapy.*

  • 2. Evaluation of asymptomatic men older than 45 years and women older than 55 years:

    • Who plan to start vigorous exercise (especially if sedentary) or

    • Who are involved in occupations in which impairment might impact public safety or who are at high risk for CAD due to other diseases (e.g. peripheral vascular disease and chronic renal failure).

• Class III: Routine screening of asymptomatic men or women.

  *Multiple risk factors are defined as hypercholesterolemia (>240 mg/dL), hypertension (systolic blood pressure >140 mmHg or diastolic blood pressure >90 mmHg), smoking, diabetes, and family history of heart attack or sudden cardiac death in a first-degree relative younger than 60 years. An alternative approach might be to select patients with a Framingham risk score consistent with at least a moderate risk of serious cardiac events within 5 years.

Valvular Heart Disease

• Class I: In chronic aortic regurgitation, assessment of functional capacity and symptomatic responses in patients with a history of equivocal symptoms.

• Class IIa:

  • 1. In chronic aortic regurgitation, evaluation of symptoms and functional capacity before participation in athletic activities.

  • 2. In chronic aortic regurgitation, prognostic assessment before aortic valve replacement in asymptomatic or minimally symptomatic patients with left ventricular dysfunction.

• Class IIb: Evaluation of exercise capacity in patients with valvular heart disease.

• Comprehensive discussion is found in the ACC/AHA valvular heart disease guidelines.

• Class III: Diagnosis of CAD in patients with moderate to severe valvular disease or with the following baseline ECG abnormalities:

  • Pre-excitation

  • Electronically paced ventricular rhythm

  • >1 mm ST depression

  • Complete left bundle-branch block

Exercise Testing Before and After Revascularization

• Class I:

  • 1. Demonstration of ischemia before revascularization.

  • 2. Evaluation of patients with recurrent symptoms that suggest ischemia after revascularization.

• Class IIa: After discharge for activity counseling and/or exercise training as part of cardiac rehabilitation in patients who have undergone coronary revascularization.

• Class IIb:

  • 1. Detection of restenosis in selected, high-risk asymptomatic patients within the first 12 months after percutaneous coronary intervention (PCI).

  • 2. Periodic monitoring of selected, high-risk asymptomatic patients for restenosis, graft occlusion, incomplete coronary revascularization, or disease progression.

• Class III:

  • 1. Localization of ischemia for determining the site of intervention

  • 2. Routine, periodic monitoring of asymptomatic patients after percutaneous coronary intervention (PCI) or coronary artery bypass grafting without specific indications.

Investigation of Heart Rhythm Disorders

• Class I:

  • 1. Identification of appropriate settings in patients with rate-adaptive pacemakers.

  • 2. Evaluation of congenital complete heart block in patients considering increased physical activity or participation in competitive sports (Level of Evidence: C).

• Class IIa:

  • 1. Evaluation of patients with known or suspected exercise-induced arrhythmias.

  • 2. Evaluation of medical, surgical, or ablative therapy in patients with exercise-induced arrhythmias (including atrial fibrillation).

• Class IIb:

  • 1. Investigation of isolated ventricular ectopic beats in middle-aged patients without other evidence of CAD.

  • 2. Investigation of prolonged first-degree atrioventricular block or type I second-degree Wenckebach, left bundle-branch block, right bundle-branch block, or isolated ectopic beats in young patients considering participation in competitive sports (Level of Evidence: C).

• Class III: Routine investigation of isolated ectopic beats in young patients.

Adapted Gibbons et al. [1].