Heart rate decline after exercise as an index of autonomic balance after myocardial infarction

To determine whether exercise testing may provide a simple means of assessing vagal reserve, the relationship between heart rate deceleration after exercise and baroreflex sensitivity (BRS) was studied in 94 patients, in whom BRS measurement and exercise testing were performed prior to discharge from hospital after acute myocardial infarction. The heart rate during exercise and the first 5 min after exercise was plotted and the rate of decline in heart rate (dr/ dt) was calculated from the slope of the rapid, early recovery phase of this curve. Log (BRS) and √ (dr/dt) were calculated. Log (BRS) correlated directly with exercise duration, but did not with dr/dt and √ (dr/dt ). Log (BRS) correlated with the product of exercise duration (ED) and √ (dr/dt), particularly in patients aged <60 years. Stepwise multiple regression yielded a formula for Log (BRS). Heart rate recovery after treadmill exercise testing may provide a simple way of assessing autonomic function after myocardial infarction