Abstract
BACKGROUND: Limited information is available regarding the prognostic potential of muscular fitness parameters in heart failure (HF) with reduced ejection fraction (HFrEF). HYPOTHESIS: We aimed to investigate the predictive potential of knee extensor muscle strength and power on rehospitalization and evaluate the correlation between exercise capacity and muscular fitness in patients newly diagnosed with HFrEF. METHODS: Ninety nine patients hospitalized with a new diagnosis of HF were recruited (64 men; aged 58.7 years [standard deviation (SD), 13.2 years]; 32.3% ischemic; ejection fraction, 28% [SD, 8%]). The inclusion criteria were left ventricular ejection fraction <40% and sufficient clinical stability to undergo exercise testing. Aerobic exercise capacity was measured with cardiopulmonary exercise testing. Knee extensor maximal voluntary isometric contraction (MVIC) and muscle power (MP) were measured using the Baltimore therapeutic equipment system. The clinical outcome was HF rehospitalization. RESULTS: Over a mean follow-up period of 1709 ± 502 days, 39 patients were rehospitalized due to HF exacerbation. HF rehospitalization was more probable for patients with diabetes and lower oxygen uptake at peak exercise (peak VO(2) ), knee extensor MVIC, and MP. The Kaplan-Meier survival analysis revealed significantly different cumulative HF rehospitalization rates according to the tertiles of peak VO(2) (P = 0.005) and MP (P = 0.002). Multivariable Cox proportional hazard model showed that the lowest tertiles of peak VO(2) (hazard ratio (HR), 6.26; 95% confidence interval (CI), 1.93-20.27); and MP (HR, 5.29; 95% CI, 1.05-26.53) were associated with HF rehospitalization. Knee extensor muscle power was an independent predictor for rehospitalization in patients with HFrEF. CONCLUSION: Knee extensor muscle power was an independent predictor for rehospitalization in patients with HFrEF.