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(I2=63%,P=0.0005);HFmrEF:HFrEF(reference)HR:0.80,95%CI:0.73-0.88(I2=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.