Abstract
AIMS: This study aims to investigate the association of resting heart rate (RHR) measured in late adolescence with long-term risk of cause-specific heart failure (HF) and subtypes of cardiomyopathy (CM), with special attention to cardiorespiratory fitness. METHODS AND RESULTS: We performed a nation-wide, register-based cohort study of all Swedish men enrolled for conscription in 1968-2005 (n = 1 008 363; mean age = 18.3 years). RHR and arterial blood pressure were measured together with anthropometrics as part of the enlistment protocol. HF and its concomitant diagnoses, as well as all CM diagnoses, were collected from the national inpatient, outpatient, and cause of death registries. Risk estimates were calculated by Cox-proportional hazards models while adjusting for potential confounders. During follow-up, there were 8400 cases of first hospitalization for HF and 3377 for CM. Comparing the first and fifth quintiles of the RHR distribution, the hazard ratio (HR) for HF associated with coronary heart disease, diabetes, or hypertension was 1.25 [95% confidence interval (CI) = 1.13-1.38] after adjustment for body mass index, blood pressure, and cardiorespiratory fitness. The corresponding HR was 1.43 (CI = 1.08-1.90) for HF associated with CM and 1.34 (CI = 1.16-1.54) for HF without concomitant diagnosis. There was an association between RHR and dilated CM [HR = 1.47 (CI = 1.27-1.71)] but not hypertrophic, alcohol/drug-induced, or other cardiomyopathies. CONCLUSIONS: Adolescent RHR is associated with future risk of HF, regardless of associated aetiological condition. The association was strongest for HF associated with CM, driven by the association with dilated CM. These findings indicate a causal pathway between elevated RHR and myocardial dysfunction that warrants further investigation.