Special prognostic phenomenon for patients with mid-range ejection fraction heart failure: a systematic review and meta-analysis

BACKGROUND: Clinical features and outcomes of heart failure (HF) with mid-range ejection fraction (HFmrEF) remain controversial. Thus, we systematically reviewed literatures of clinical research to assess and analyze characteristics and prognosis of patients with HFmrEF. METHODS: PubMed, Embase, and Web of Science were searched for cohort studies up to April 23, 2019. Clinical features and multivariate adjusted hazard ratios (HRs) of endpoints of short-term all-cause mortality (SAM), long-term all-cause mortality (LAM), long-term cardiovascular death (LCD) and long-term HF rehospitalization (LHR) among patients with HFmrEF and HF with preserved ejection fraction (HFpEF), HF with reduced ejection fraction (HFrEF) were well addressed. The primary outcome was LAM. RESULTS: Totally 19 studies were included in this study with 164,678 patients enrolled. The follow-up time of LAM was 3.6 ± 2.5 years. HRs of LAM, SAM, LCD, LHR indicated that the risks of patients with HFmrEF were higher than HFpEF patients but lower than HFrEF patients, as for LAM, HFmrEF:HFpEF (reference) HR: 1.07, 95% confidence interval (CI): 1.00-1.15 (I = 63%, P = 0.0005); HFmrEF:HFrEF (reference) HR: 0.80, 95% CI: 0.73-0.88 (I = 70%, P < 0.0001). However, HFmrEF patients had the lowest rate in LAM (30.94%), SAM (2.73%), LCD (17.45%), LHR (26.36%) compared with the other two groups. CONCLUSIONS: This systematic review and meta-analysis compared features and prognosis between patients with HFmrEF and HFpEF, HFrEF by HRs. There appeared a special "separation phenomenon" showing rates of endpoints were inconsistent with their hazards in patients with HFmrEF compared with HFpEF patients.