Abstract 16972: Midlife Cardiorespiratory Fitness Predicts Late-Life Risk for Heart Failure Independent of Interval Development of Hypertension, Diabetes, and Myocardial Infarction

Abstract

Background: Physical inactivity is associated with higher risk factors for heart failure (HF) as well as an increased risk for HF events. The extent to which the association between physical inactivity and HF events is mediated by interval development of diabetes (DM), hypertension (HTN), or acute myocardial infarction (MI) is unknown.

Methods: Individual subject data from the Cooper Center Longitudinal Study (CCLS) were linked with Medicare claims files. We studied 20,642 subjects (21.2% women, mean age 49 years) with no prior cardiovascular disease who had baseline cardiorespiratory fitness (CRF) in METs estimated by Balke protocol treadmill time between 1970 and 2009 and later had Medicare coverage between 1999 and 2009. Hospitalization for MI or HF, incident DM, and incident HTN were drawn from Medicare claims files. Associations between midlife CRF and HF hospitalization after age 65 were assessed by applying a proportional hazards model to the multivariate failure time data with MI, DM, and HTN entered as time-dependent covariates.

Results: After 133,514 person years of Medicare follow up, we observed 1,051 HF hospitalizations, 832 MI hospitalizations, 9,266 new HTN cases, and 3,545 new DM cases. Higher midlife CRF, adjusted for baseline risk factors, was associated with a lower risk for HF hospitalization at an older age [adj. hazard ratio (95% CI): 0.81 (0.76-0.87) per 1 MET]. As expected, the presence of MI, HTN, and DM during follow-up were all strongly associated with a higher risk for HF hospitalization. However, the association between midlife CRF and HF risk was only minimally attenuated after adjustment for the development of interval MI, HTN, and DM (see Table).

Conclusion: Higher CRF in mid life is strongly associated with lower HF risk decades later, independent of interval HF risk factors such as MI, HTN, and DM. This suggests higher fitness may prevent heart failure through novel protective mechanisms.