Cardiorespiratory fitness and incident heart failure: The Henry Ford Exercise Testing (FIT) Project

Background Prior studies have demonstrated cardiorespiratory fitness (CRF) to be a strong marker of cardiovascular health. However, there are limited data investigating the association between CRF and risk of progression to heart failure (HF). The purpose of this study was to determine the relationship between CRF and incident HF. Methods We included 66,329 patients (53.8% men, mean age 55 years) free of HF who underwent exercise treadmill stress testing at Henry Ford Health Systems between 1991 and 2009. Incident HF was determined using International Classification of Diseases, Ninth Revision codes from electronic medical records or administrative claim files. Cox proportional hazards models were performed to determine the association between CRF and incident HF. Results A total of 4,652 patients developed HF after a median follow-up duration of 6.8 (+/- 3) years. Patients with incident HF were older (63 vs 54 years, P <.001) and had higher prevalence of known coronary artery disease (42.3% vs 11%, P <.001). Peak metabolic equivalents (METs) of task were 6.3 (+/- 2.9) and 9.1 (+/- 3) in the HF and non-HF groups, respectively. After adjustment for potential confounders, patients able to achieve >= 12 METs had an 81% lower risk of incident HF compared with those achieving <6 METs (hazard ratio 0.19 [95% CI 0.14-0.29], P for trend <.001). Each 1 MET achieved was associated with a 16% lower risk (hazard ratio 0.84 [95% CI 0.82-0.86], P <.001) of incident HF. Conclusions Our analysis demonstrates that higher level of fitness is associated with a lower incidence of HF independent of HF risk factors.