Abstract 36: Fitness and Reclassification of Risk for Incidence of Heart Failure: The Veterans Exercise Testing Study
Background: It is well-established that fitness is inversely associated with cardiovascular and all-cause mortality, but little is known regarding the association between cardiorespiratory fitness (CRF) and incidence of heart failure (HF).
Methods: CRF was determined in 21,080 US Veterans (mean age 58.3 ± 11) free of HF at baseline from the Veterans Affairs Medical Centers in Washington, DC and Palo Alto, CA, and followed for a mean of 12.3±7.4 years. Subjects were classified by quintiles of fitness based on age-specific peak metabolic equivalents (METs) achieved. Participants were followed for incidence of HF, determined through review of computerized medical records. Multivariable Cox models were used to determine the association between incidence of HF and clinical and exercise test variables. Reclassification characteristics of fitness relative to standard clinical risk factors were determined using the category-free net reclassification improvement index (NRI), and the integrated discrimination improvement.
Results: During the follow-up, 1902 subjects (9%) developed HF, with an average annual incidence rate of 7.4 events per 1,000 person-years. When fitness status was considered as a binary variable (Unfit/Fit), low fitness was the strongest predictor of risk for HF among clinical and exercise test variables (HR 1.91, 95% CI 1.74-2.09, p<0.001). In a fully adjusted model with the least fit group as the reference, there was a graded and progressive reduction in risk for HF as fitness level was higher. Risks for developing HF were 36%, 41%, 67%, and 76% lower among increasing quintiles of fitness compared to the least fit subjects (p<0.001) (Figure). Adding CRF to standard risk factors resulted in an NRI of 0.37 (p<0.001).
Conclusion: CRF is strongly and inversely associated with future incidence of HF, and significantly reclassifies risk for HF. Reducing the growing burden of HF by improving fitness provides an additional impetus for health care providers to recommend physical activity.
Author Disclosures: J. Myers: None. P. Kokkinos: None. K. Chan: None. E. Dandekar: None. B. Yilmaz: None. A. Nagare: None. C. Faselis: None. M. Soofi: None.
- © 2017 by American Heart Association, Inc.