Objective: A relative hyperadrenergic tone related to abnormalities of the autonomic nervous system is suspected in the mechanisms of sudden death. Therefore, we assessed the role of an elevated basal heart rate in the occurrence of sudden death in a long-term cohort study.
Methods: 7746 subjects aged 42--53 years, underwent ECG and physical examination conducted by a physician under standardized conditions, provided blood samples for laboratory tests, and answered questionnaires administered by trained interviewers. The vital status was obtained from specific inquiries up to the time of retirement and then by death certificates. Men with known ischemic heart disease were further excluded from analysis which was conducted on the 7079 remaining subjects.
Results: After an average follow-up period of 23 years, there were 2083 deaths, among which were 603 cardiovascular deaths including 118 sudden deaths and 192 following myocardial infarction. The crude risk of sudden death increased linearly with the level of resting heart rate and the risk in men in the highest quintile of heart rate was 3.8 fold than in those in the lowest quintile, whereas rates were approximatively twice higher for fatal myocardial infarction, cardiovascular and total mortality (all P<0.01). When age, body mass index, systolic blood pressure, tobacco consumption, parental history of myocardial infarction and parental history of sudden death, cholesterol level, diabetic status, and sport activity were simultaneously entered into the survival model, resting heart rate remained an independent risk factor for sudden death (P=0.03) but not for fatal myocardial infarction.
Conclusion: An elevated heart rate at rest was confirmed as an independent risk factor for sudden death in middle-aged men.