Heart-rate recovery immediately after exercise as a predictor of mortality

Background The increase in heart rate that accompanies exercise is due in p art to a reduction in vagal tone. Recovery of the heart rate immediately af ter exercise is a function of vagal reactivation. Because a generalized dec rease in vagal activity is known to be a risk factor for death, we hypothes ized that a delayed fall in the heart rate after exercise might be an impor tant prognostic marker. Methods For six years we followed 2428 consecutive adults (mean [+/-SD] age , 57+/-12 years; 63 percent men) without a history of heart failure or coro nary revascularization and without pacemakers. The patients were undergoing symptom-limited exercise testing and single-photon-emission computed tomog raphy with thallium scintigraphy for diagnostic purposes. The value for the recovery of heart rate was defined as the decrease in the heart rate from peak exercise to one minute after the cessation of exercise. An abnormal va lue for the recovery of heart rate was defined as a reduction of 12 beats p er minute or less from the heart rate at peak exercise. Results There were 213 deaths from all causes. A total of 639 patients (26 percent) had abnormal values for heart-rate recovery. In univariate analyse s, a low value for the recovery of heart rate was strongly predictive of de ath (relative risk, 4.0; 95 percent confidence interval, 3.0 to 5.2; P<0.00 1). After adjustments were made for age, sex, the use or nonuse of medicati ons, the presence or absence of myocardial perfusion defects on thallium sc intigraphy, standard cardiac risk factors, the resting heart rate, the chan ge in heart rate during exercise, and workload achieved, a low value for he art-rate recovery remained predictive of death (adjusted relative risk, 2.0 ; 95 percent confidence interval, 1.5 to 2.7; P<0.001). Conclusions A delayed decrease in the heart rate during the first minute af ter graded exercise, which may be a reflection of decreased vagal activity, is a powerful predictor of overall mortality, independent of workload, the presence or absence of myocardial perfusion defects, and changes in heart rate during exercise. (N Engl J Med 1999;341:1351-7.) (C) 1999, Massachuset ts Medical Society.