Abstract
BackgroundPrior studies have demonstrated low cardiorespiratory fitness as a strong marker for coronary heart disease. However, there is limited data investigating the association between fitness and risk of heart failure (HF).HypothesisUtilizing data from the Henry Ford Exercise Testing (FIT) Project, we hypothesized that a higher level of fitness is inversely associated with incident HF.MethodsWe included 66,329 patients (53.8% males, mean age 55 years) free of HF who underwent clinician-referred exercise treadmill stress testing at Henry Ford Health System between 1991 and 2009. Incident HF was determined using ICD-9 codes from electronic medical records or administrative claims files. Cox proportional hazards models were performed to determine the independent association between fitness and incident HF.ResultsA total of 4,652 patients developed HF after a median follow-up duration of 6.8 years. Patients with incident HF were older (63 years vs 54 years, p<0.001) had higher prevalence of hypertension (83.1% vs 63.1%, p<0.001), prior coronary artery disease (CAD) (42.3% vs. 11%, p <0.001), and type II diabetes (33.8% vs. 17.9%, p<0.001). Peak metabolic equivalents of task were 9.1 and 6.3 in the non-HF and HF groups respectively. After adjustment for potential confounders, patients able to achieve ≥12 METs had an 84% lower risk of incident HF compared to those achieving <6 METs (hazard ratio 0.18 [95% CI 0.13-0.23] ; p-trend <0.001). Each 1 MET higher achieved from baseline was associated with a 17% lower risk (HR 0.83 [95% CI 0.81- 0.85]; P < 0.001) of incident HF. The relationship remained constant across age, sex, race, CAD, diabetes, and hypertension strata.ConclusionsOur analysis suggests that higher level of fitness is associated with a lower incidence of HF independent of HF specific risk factors.