HEART-RATE INCREASE AND MAXIMAL HEART-RATE DURING EXERCISE AS PREDICTORS OF CARDIOVASCULAR MORTALITY - A 16-YEAR FOLLOW-UP-STUDY OF 1960 HEALTHY-MEN

Background: Resting heart rate is directly associated and maximal exer cise-induced heart rate inversely associated with cardiovascular morta lity, and therefore their difference might contain prognostic informat ion from both variables. The comparative long-term prognostic values o f maximal exercise-induced heart rate and of the difference between it and resting heart rate were studied in apparently healthy middle-aged men. Methods: Resting heart rate and maximal exercise-induced heart r ate were measured, and their difference calculated, in 1960 apparently healthy men aged 40-59 years, and mortality was recorded over a perio d of 16 years. Conventional coronary risk factors were assessed at bas eline. Results: Both the difference between the two heart rates and th e maximal exercise-induced heart rate were strongly, independently and inversely associated with cardiovascular mortality after adjustment f or age, smoking, systolic blood pressure, lung function, glucose toler ance, serum cholesterol level, serum triglycerides level, physical fit ness and exercise ECG findings. The adjusted relative risk of cardiova scular death in heart-rate difference quartiles 3 and 4 compared with that in quartile 1 (the lowest heart-rate difference quartile) was 0.5 4 (95% confidence interval 0.33-0.86; P=0.009). The corresponding valu e for maximal exercise-induced heart rate was 0.56 (95% confidence int erval 0.34-0.89; P=0.018). Within the lowest heart-rate difference qua rtile, but not within the lowest maximal exercise-induced heart rate q uartile, a further, strong, negative gradient in cardiovascular mortal ity was observed. In the high working capacity range, low heart-rate d ifference but not low maximal exercise-induced heart rate predicted ve ry high cardiovascular disease mortality. Heart-rate difference and ma ximal exercise-induced heart rate were also inversely associated with non-cardiovascular disease mortality. Conclusions: Both heart-rate dif ference and maximal exercise-induced heart rate were strong, graded, l ong-term predictors of cardiovascular mortality among apparently healt hy middle-aged men, independent of age, physical fitness and conventio nal coronary risk factors. However, low heart-rate difference was a be tter predictor than low maximal exercise-induced heart rate for recogn izing individuals who were at particularly high risk of dying prematur ely from cardiovascular diseases.