The Second Universal Definition of Heart Failure (2026). What’s new?

The first Universal Definition and Classification of Heart Failure, published in 2021, standardized the conceptual framework and terminology of heart failure (HF), including pre-HF, HFmrEF, and HFimpEF. The Second Universal Definition (2026), developed by a joint AHA/ACC/ESC/WHF Task Force in collaboration with the HFSA, HFA, and JHFS, builds on this foundation by refining the diagnostic framework and classification of HF. It moves away from rigid left ventricular ejection fraction (LVEF) thresholds for distinguishing HFrEF from HFpEF and proposes three broad LVEF-based categories-HFrEF, HFpEF, and HFimpEF-without retaining HFmrEF as a separate category in the proposed framework. It also proposes a universal classification of HF causes independent of LVEF and clarifies the distinction between worsening and decompensated HF. A broader global perspective incorporates geographic variation in etiology and the influence of social determinants on HF risk and outcomes. This article summarizes the key updates introduced in the 2026 Universal Definition of Heart Failure.