Functional limitation predicts mortality in heart failure with preserved ejection fraction

Background: While the prognostic value of six-minute walking test (6MWT) in patients with heart failure (HF) and reduced ejection fraction has been firmly established, there are few or no data correlating the distance walked during 6MWT (6MWD) with mortality in patients with HF with preserved ejection fraction (HFpEF) Methods: We studied 482 patients with HFpEF who had been admitted to inpatients cardiac rehabilitation. The primary outcome was 3-year all-cause mortality. The association between 6MWD and the primary outcome was assessed using multivariable models. Established risk markers were incorporated into the models. Results: 174 patients died during the 3-year follow-up. Taking the highest tertile of 6MWD (>= 360 m) as reference, the adjusted hazard ratio (HR) of the primary outcome was 2.23 (95 % CI 1.31-3.78; p = .003) for the patients in the intermediate tertile (241-359 m) and 4.94(95% CI 2.90-8.39; p < .001) for those in the lowest tertile (<240 m). The annual mortality rate was 25.0 % in the lowest tertile, 10.9 % in the intermediate tertile, and 5.3 % in the highest tertile. When the distance walked was normalized for age, sex, and body mass index and expressed as percent-of-predicted walking distance, the adjusted HR was 1.30 (95% CI 0.76-2.22; p = .331) for the patients in the intermediate tertile (58.2 % to 77.6%) and 3.52 (95% CI 2.12-5.85; p < .001) for those in the lowest tertile (<58.1 %). Conclusions: Our findings suggest that measuring functional capacity by evaluating the distance that a patient can walk over a period of 6 min provides important prognostic information in HFpEF.