LAUSR

For decades, left ventricular ejection fraction (LVEF) has been the mainstay metric for classifying patients within clinical trials for heart failure (HF). Nearly all landmark clinical outcome trials resulting in therapeutic advances for patients with HF have utilized an LVEF cut-off within trial eligibility criteria. As such, clinical guidelines remain anchored to LVEF, with specific therapeutic recommendations for each LVEF phenotype. Nonetheless, limitations of LVEF have long been recognized, including lack of consistent pathophys-iological basis, dependency on haemodynamic loading conditions and rhythm status, insensitivity to subtle changes in contractility, and moderate reproducibility owing to high intra-observer and inter-observer variability. 1 –3 Moreover, recent clinical trials have shown that medications once believed to be effective only for patients with LVEF ≤ 35%–40% offer clinical benefits with LVEF ranges above this cut point. 4,5 These newer data have further spurred significant debate in the HF community over the continued use of LVEF in classifying HF, with some suggesting LVEF may be removed as the primary classification system for HF. Yet, the magnitude of clinical benefits with therapies, and whether all-cause mortality is reduced or not, has been strongly associated with LVEF. However, while acknowledging the limitations of LVEF, we believe the foundational role that LVEF classification has served in evidence generation for HF therapeutics makes its abandonment impractical and unwise. In this viewpoint,