Heart-Rate Profile during Exercise as a Predictor of Sudden Death

Changes in heart rate during exercise and recovery from exercise are mediated by the balance between sympathetic and vagal activity. Since alterations in the neural control of cardiac function contribute to the risk of sudden death, we tested the hypothesis that among apparently healthy persons, sudden death is more likely to occur in the presence of abnormal heart-rate profiles during exercise and recovery.

A total of 5713 asymptomatic working men (between the ages of 42 and 53 years), none of whom had clinically detectable cardiovascular disease, underwent standardized graded exercise testing between 1967 and 1972. We examined data on the subjects' resting heart rates, the increase in rate from the resting level to the peak exercise level, and the decrease in rate from the peak exercise level to the level one minute after the termination of exercise.