Cardiorespiratory Fitness and Reclassification of Risk for Incidence of Heart Failure

Abstract

Background— It is well established that cardiorespiratory fitness (CRF) is inversely associated with cardiovascular and all-cause mortality. However, little is known regarding the association between CRF and incidence of heart failure (HF). Methods and Results— Between 1987 and 2014, we assessed CRF in 21 080 HF-free subjects (58.3±11 years) at the Veterans Affairs Medical Centers in Washington, DC, and Palo Alto, CA. Subjects were classified by age-specific quintiles of CRF. Multivariable Cox models were used to determine the association between HF incidence 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 and integrated discrimination improvement indices. During the follow-up (mean 12.3±7.4 years), 1902 subjects developed HF (9.0%; average annual incidence rate, 7.4 events per 1000 person-years). When CRF was considered as a binary variable (unfit/fit), low fitness was the strongest predictor of risk for HF among clinical and exercise test variables (hazard ratio, 1.91; 95% confidence interval, 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 with the least-fit subjects ( P <0.001). Adding CRF to standard risk factors resulted in a net reclassification improvement of 0.37 ( P <0.001). Conclusions— CRF is strongly, inversely, and independently associated with the incidence of HF in veterans referred for exercise testing.

Cardiorespiratory fitness, body mass index and heart failure incidence

“…In the current study, the 16% lower risk per 1 MET increase in CRF is similar to that reported by these previous studies . Collectively, the salient clinical implications of the present findings and previous reports is that moderate levels of physical activity that lead to at least moderate increases in CRF can potentially play an important role in the prevention of HF. Failing to meet moderate CRF levels has at least equally, if not more deleterious consequences as traditional co‐morbidities associated with HF.…”

“…Previous studies have reported higher rates of hospitalization for HF in the least‐fit quartile of subjects vs. the highest‐fit quartile and 17–21% lower risks of HF hospitalization and HF incidence for each 1 MET increment in CRF . In the current study, the 16% lower risk per 1 MET increase in CRF is similar to that reported by these previous studies .…”

“…Previous studies have reported higher rates of hospitalization for HF in the least‐fit quartile of subjects vs. the highest‐fit quartile and 17–21% lower risks of HF hospitalization and HF incidence for each 1 MET increment in CRF . In the current study, the 16% lower risk per 1 MET increase in CRF is similar to that reported by these previous studies . Collectively, the salient clinical implications of the present findings and previous reports is that moderate levels of physical activity that lead to at least moderate increases in CRF can potentially play an important role in the prevention of HF.…”

“…In a large cohort of US veterans, the association between CRF and HF incidence was strong, independent and graded. The risk for developing HF was 19% lower for each one metabolic equivalent (MET) increment increase in exercise capacity . Compared with the least‐fit category (4.3 ± 1.2 METs), the risk of HF was 34% lower for individuals in the next CRF category (6.0 ± 1.2 METs) and 76% lower for individuals in the highest CRF (≥12 METs).…”

“…There is also strong evidence of an inverse association between cardiorespiratory fitness (CRF) and the incidence of chronic disease, including HF . In a large cohort of US veterans, the association between CRF and HF incidence was strong, independent and graded.…”