Cardiorespiratory fitness and risk of heart failure: a population-based follow-up study

Aim To examine the relationship between cardiorespiratory fitness (CRF) and risk of incident heart failure (HF). Methods and results Cardiorespiratory fitness, as measured by maximal oxygen uptake (VO(2)max), was assessed at baseline in a prospective cohort of 1873 men aged 42-61 years without HF or chronic respiratory disease. During a mean follow-up of 20.4 years, 152 incident HF events were recorded. Within-person variability was calculated using data from repeat measurements taken 11 years apart. The age-adjusted hazard ratio (HR) per unit increase (1 mL/kg/min of VO(2)max) in CRF was 0.89 [95% confidence interval (CI) 0.86-0.93], which was minimally attenuated to 0.94 (95% CI 0.90-0.98) after further adjustment for established HF risk factors (body mass index, systolic blood pressure, history of cardiovascular disease, diabetes, heart rate, and LV hypertrophy) and incident coronary events as a time-varying covariate. In a comparison of extreme quartiles of CRF levels (VO(2)max >= 35.4 vs. <= 25.7 mL/kg/min), the corresponding HRs were 0.27 (0.15-0.50) and 0.48 (0.25-0.92), respectively. Each 1 MET (metabolic equivalent of oxygen consumption) increment in CRF was associated with a 21% (7-33%) reduction in multivariable adjusted risk of HF. Addition of CRF to a HF risk prediction model containing established risk factors did not significantly improve risk discrimination (C-index change = 0.0164, P = 0.07). Conclusions In this Finnish population, there is a strong, inverse, and independent association between long-term CRF and HF risk, consistent with a dose-response relationship. The protective effect of CRF on HF risk warrants further evaluation.