While electrocardiographic abnormalities during treadmill stress testing are predictive of increased risk for cardiac disease and death, valuable prognostic information can be gained from monitoring during the post-exercise recovery phase. Frolkis and colleagues present data on frequent ventricular ectopy during the recovery phase as a predictor of subsequent mortality.
Data were derived from 29,244 consecutive patients who underwent treadmill stress testing over a 10-year period at a Cleveland cardiac referral center. Criteria for exclusion from the study included symptomatic heart failure, atrial fibrillation or other arrhythmia, and frequent ventricular ectopy at rest. The authors defined frequent ventricular ectopy as seven or more single premature ventricular beats per minute or any run of more than two ventricular ectopic beats. Ventricular ectopy occurred in seven percent of the 29,244 patients. Ectopy occurred during exercise in 3 percent, during the recovery phase in 2 percent, and during both exercise and recovery in 2 percent. Frequent ventricular ectopy was more common in older patients, and those with known coronary artery disease, hypertension, and decreased exercise tolerance. A subnormal increase in heart rate with exercise as well as a delayed return to the resting heart rate after exercise also predicted frequent ventricular ectopy. Over a mean follow-up period of 5.3 years, there was increased all-cause mortality in those with frequent ventricular ectopy. Ventricular ectopy during exercise was associated with a 9 percent mortality rate, compared to a 5 percent mortality rate in those without ectopy. Frequent ventricular ectopy observed during the recovery phase of treadmill testing increased the death rate even further to 11 percent. Those patients with ventricular ectopy during both exercise and recovery had the lowest survival rate. When the authors used statistical controls for the baseline variables known to be associated with ectopy (e.g., older age, known coronary disease), recovery phase ectopy was still independently associated with decreased survival, but ventricular ectopy during exercise was not.
The authors conclude that frequent ventricular ectopy during treadmill stress testing was associated with decreased survival rates, especially when this ectopy occurred in the post-exercise recovery phase.