Prevalence and prognosis of respiratory muscle weakness in heart failure patients with preserved ejection fraction.

Although respiratory muscle weakness (RMW) is known to predict prognosis in patients with heart failure with reduced ejection fraction (HFrEF), RMW prevalence and its prognosis in those with preserved ejection fraction (HFpEF) remain unknown. We aimed to investigate whether the RMW predicted mortality in HFpEF patients.We conducted a single-centre observational study with consecutive 1023 heart failure patients (445 in HFrEF and 578 in HFpEF). Maximal inspiratory pressure (PI) was measured to assess respiratory muscle strength at hospital discharge, and RMW was defined as PI <70% of predicted value. Endpoint was all-cause mortality after hospital discharge, and we examined the influence of RMW on the endpoint.Over a median follow-up of 1.8 years, 134 patients (13.1%) died; of these 53 (11.9%) were in HFrEF and 81 (14.0%) in HFpEF. RMW was evident in 190 (42.7%) HFrEF and 226 (39.1%) HFpEF patients and was independently associated with all-cause mortality in both HFrEF (adjusted hazard ratio [HR]: 2.13, 95% confidence interval [CI]: 1.17-3.88) and HFpEF (adjusted HR: 2.85, 95% CI: 1.74-4.67) patients. Adding RMW to the multivariate logistic regression model significantly increased area under the receiver-operating characteristic curve (AUC) for all-cause mortality in HFpEF (AUC including RMW: 0.78, not including RMW: 0.74, P = 0.026) but not in HFrEF (AUC including RMW: 0.84, not including RMW: 0.82, P = 0.132).RMW was observed in 39% of HFpEF patients, which was independently associated with poor prognosis. The additive effect of RMW on prognosis was detected only in HFpEF but not in HFrEF.