Comparative effectiveness of exercise testing and continuous monitoring for detecting arrhythmias in patients with previous myocardial infarction.

Abstract

To detect unsuspected arrhythmias, 60 patients with previous myocardial infarction were studied by both submaximal treadmill exercise testing and 10 hours of continuous ECG monitoring (Holter technique) during normal activity. Significant arrhythmias were detected in 28 of 60 patients (47%). Eight patients (13%) had one or more premature ventricular contractions on their resting ECG and all had significant arrhythmias detected by exercise and/or Holter monitoring. Eighteen patients (30%) had frequent ectopic beats during or within 15 minutes after treadmill exercise and 22 patients (37%) had significant arrhythmias during continuous ECG monitoring. In 10 patients (17%) continuous ECG monitoring detected significant arrhythmias when exercise did not, while in six instances (10%) frequent premature ventricular beats were present with exercise but not during Holter monitoring. In four of 12 patients in whom both tests were positive, continuous ECG monitoring detected ventricular tachycardia when exercise showed only isolated ectopic ventricular beats. Fourteen patients (23%) had major arrhythmias detected by ECG monitoring; only six of the 14 were also detected by exercise testing. We conclude that both treadmill exercise and continuous ECG monitoring are useful for arrhythmia detection in post myocardial infarction patients but that continuous ECG monitoring often discloses different and more serious arrhythmias than treadmill exercise.