Heart Failure Syndromes: Different Definitions of Different Diseases—Do We Need Separate Guidelines? A Narrative Review

Heart failure (HF) is a well-known leading cause of mortality, associated with a high symptom burden in advanced stages, frequent hospitalizations, and increasing economic costs. HF is typically classified into three main subgroups, based on left ventricular ejection fraction (LVEF): HF with reduced ejection fraction (HFrEF), HF with mildly reduced ejection fraction (HFmrEF), and HF with preserved ejection fraction (HFpEF). Recently, two additional subgroups have been proposed: HF with improved ejection fraction (HFimpEF) and HF with supernormal ejection fraction (HFsnEF). These five phenotypes exhibit distinct risk factors, clinical presentations, therapeutic responses, and prognosis. However, the LVEF thresholds used to define these subgroups remain a subject of considerable debate, with significant differences in opinions among leading experts. A major criticism concerns the reliability of LVEF in accurately classifying HF subgroups. Due to substantial intra and interobserver variability, determining the appropriate therapy and prognosis can be challenging, particularly in patients with HFmrEF. Additionally, patients classified under HFpEF are often too heterogeneous to be effectively managed as a single group. This narrative review explores these issues, and suggests a possible need for a new approach to HF classification, one that involves revising the LVEF reference values for HF phenotypes and highlighting LVEF trajectories rather than relying on a single measurement. Moreover, in light of the relatively limited therapeutic options for patients with LVEF > 40%, a new, simplified classification may be proposed: HF with reduced EF (LVEF ≤ 40%), HF with below-normal EF (41% ≤ LVEF ≤ 55%), and HF with normal EF (LVEF > 55%). This mindset would better equip clinical cardiologists to manage the diverse spectrum of HF syndromes, always with the patient at the center.