Evaluation of cardiac arrhythmias by exercise testing.

Exercise testing is an important noninvasive method for the exposure of arrhythmias. It provides complementary information to that obtained from ambulatory monitoring or electrophysiologic testing. By producing a number of important physiologic changes, especially activation of the sympathetic nervous system and an increase in circulating catecholamines, exercise testing provides a more complete assessment. On continuous monitoring, exercise-induced ventricular premature beats may be found in up to 34% of healthy subjects, in 60 to 70% of those with heart disease and in all patients who have experienced sustained ventricular tachycardia. Couplets or nonsustained ventricular tachycardia can be found during exercise in 0 to 6% of healthy subjects, in 15 to 31% of patients with heart disease and in 75% of those with sustained ventricular tachycardia. Even in patients with heart disease, there is only a small risk of inducing sustained ventricular tachycardia or ventricular fibrillation during exercise. The prognostic relevance of exercise-induced ventricular arrhythmias in patients with coronary artery disease or cardiomyopathy has not been clearly established. There appears to be an increased risk, however, in patients with ventricular premature beats as well as ST-segment depression or in patients with repetitive forms of ventricular arrhythmias during exercise which cannot be medically controlled. In healthy subjects, exercise-induced ventricular premature beats are of no prognostic relevance. In particular, for patients in whom arrhythmias are induced by exercise, exercise testing should be used to assess the effectiveness of antiarrhythmic drug treatment. Importantly, serious cardiac toxicity, often not observed at rest or during routine activities, may become apparent during exercise testing. It should be a standard part of arrhythmia assessment and management.