The objectives of the study were to characterize and compare different acute heart failure (AHF) subgroups according to left-ventricular ejection fraction (LVEF) in terms of all-cause mortality and HF-related readmissions during the 1-year follow-up (FU). Three hundred and fifty-six AHF patients admitted to Cardiology ward and/or CCU were retrospectively included in the study and analyzed during the 1-year FU. Patients were stratified according to LVEF as those with preserved (HFpEF), midrange (HFmrEF) and reduced LVEF (HFrEF). During the FU period, 148 (43.3%) patients died, and 116 HF-related readmission events were recorded. HFmrEF group had significantly higher standardized all-cause mortality rate, unadjusted for age, compared to HFpEF group and significantly lower than HFrEF group (41 vs. 18 and 41 vs. 62.5 events per 100 patient-years; χ² = 41.08, p < 0.001 and χ² = 16.62, p < 0.001, respectively). A propensity score-matched analysis in which all HF groups were matched for age and other covariates confirmed that HFmrEF group had significantly higher all-cause mortality rate than HFpEF group (χ² = 15.66, p < 0.001) while no significant differences in readmission rates were observed across all groups (p = NS). The hazard risk for a composite endpoint of death and readmission was highest in HFrEF group (HR 6.53, 95% CI 3.53–12.08, p < 0.001), followed by HFmrEF group (HR 3.30, 95% CI 1.86–5.87, p < 0.001) when compared to HFpEF group set as a reference. Among AHF patients, the HFmrEF phenotype was associated with significantly higher all-cause mortality compared to HFpEF, during the 1-year FU. This finding might implicate more stringent clinical approach towards this patient group.