Gu J, et al. - Considering that left ventricular ejection fraction (LVEF) holds significance on treatment decisions and prognosis in heart failure (HF), these patients are typically designated as having reduced, mid-range, or preserved ejection fraction (EF) (HFrEF, HFmrEF, or HFpEF, respectively), but such designations are not certainly static, as there are many transitions among the three HF phenotypes during follow-up, so, researchers evaluated the HF transitions over time as well as their clinical features, prognosis, and response to medical treatment in this prospective longitudinal cohort analysis. In this study with 1,920 patients with a primary diagnosis of HF, three groups based on baseline and 1-year follow-up echocardiography were defined: HF with improved EF (HFiEF), HF with deteriorated EF (HFdEF), and HF with unchanged EF (HFuEF). Five-year all-cause mortality was the primary outcome. Higher mortality was reported in HFdEF cases, whereas lower mortality was seen in HFiEF cases. A 62.1% reduced risk for mortality was observed in relation to HFiEF vs HFuEF, after adjustment. Improved prognosis related to the use of beta-blockers was reported in patients with HFiEF and HFuEF. Findings revealed LVEF as a dynamic factor associated with coexisting conditions and drug therapy among patients with HF. HFiEF and HFdEF were acknowledged as different HF phenotypes with distinct clinical results compared with other phenotypes.