Introduction: Definitions of heart failure (HF) with preserved ejection fraction (HFpEF) and with reduced EF (HFrEF) are variable in prior literature. There is significant overlap of left ventricular EF in the range of 40-49% in studies exploring clinical features of subtypes of HF. The goal of this study is to explore characteristics of HF with mid-range EF (HFmrEF, EF 40-49%).
Hypothesis: Patients with HFmrEF have unique baseline characteristics and mortality outcome, compared with other HF groups.
Methods: Adult patients who had HF diagnosis (ICD 9 code 428.*) upon initial hospitalization at Montefiore Medical Center between 2008-2013 were included. HF with mid-range, reduced and preserved EF were classified based on the EF derived from echocardiography. Median follow-up time was 5.2 years and clinical endpoint was all-cause mortality. Cumulative probabilities were estimated and multivariable adjusted Cox proportional regression was performed to study the predictors of mortality.
Results: Of the 6,833 HF patients in the study, 2,385 (34.9%), 2,425 (34.5%) and 2,023 (29.6%) patients were classified as HFmrEF, HFrEF and HFpEF, respectively. Baseline characteristics of HFmrEF resembled HFrEF group, with male prominence and a higher prevalence of prior myocardial infarction (35.9% and 33.1% in HFmrEF and HFrEF, respectively), compared to HFpEF (11.6%) group (p < 0.001). Cumulative mortality of HFmrEF (25.2%) was comparable to that of HFrEF (26.0%), and was significantly higher than HFpEF (14.4%, p < 0.001). Advanced age, chronic kidney disease and chronic lung disease were associated with increased mortality in all three HF groups. Diabetes was associated with increased mortality in HFrEF and HFmrEF but not HFpEF group; whereas baseline EF was an independent predictor of mortality only in HFrEF group but not in either HFmrEF or HFpEF group.
Conclusions: Patients with HFmrEF manifested a phenotype more similar to HFrEF. A distinct set of mortality predictors in HFmrEF patients was revealed in the studied population, highlighting some unique features of HFmrEF.