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.