Higher Midlife Cardiorespiratory Fitness is Associated with Lower Risk for the Development of Symptomatic Heart Failure

Background: The protective association of cardiorespiratory fitness (CRF) with cardiovascular morbidity and mortality is well established. However, the association of midlife CRF with the development of symptomatic heart failure (HF) later in life is unknown. Methods: Asymptomatic self-referred adults aged 40-79 years were evaluated annually in a screening program. At baseline, all subjects were free of heart failure symptoms and completed maximal exercise stress test according to the Bruce. Fitness was categorized into age- and sex-specific quintiles (Q) according to treadmill time. High fitness was defined as Q3-5 groups. Primary end-point was the development of symptomatic HF. All HF events were adjudicated by the authors. Results: Final study population included 20,092 subjects. The median age was 49 years (Interquartile range [IQR] 44-55) and 71% were men. During median follow up time of 14 years (IQR 8-18), 272 (1.3%) subjects developed symptomatic HF. HF was of ischemic origin in 129 (47%) vs non-ischemic in 143 (53%); and of diastolic pattern in 163 (64%) vs. systolic in 94 (36%). Cox regression model adjusted for age and gender demonstrated that subjects with high CRF had a 23% risk reduction for the development of HF during follow up (95% CI 0.53-0.85; p<.001). A multivariable model adjusted for age, gender, ASCVD risk score, and IHD as a time-dependent covariate demonstrated that subjects with high baseline fitness were 32% less likely to develop HF (95% CI 0.53-0.86 p=.001). Conclusions: Higher CRF is associated with reduced risk for the development of symptomatic HF later in life. These findings indicate a potential contribution of exercise training for the prevention of HF in advanced age.