Worsening Heart Failure: Nomenclature, Epidemiology, and Future Directions: JACC Review Topic of the Week.

Heart failure (HF) is a progressive disease characterized by variable durations of symptomatic stability often punctuated by episodes of worsening despite continued therapy. These periods of clinical worsening are increasingly recognized as a distinct phase in the history of HF, termed worsening HF (WHF). The definition of WHF continues to evolve from a historical focus solely on hospitalization to now include nonhospitalization events (eg, need for intravenous diuretic therapy in the emergency or outpatient setting). Most HF clinical trials to date have had HF hospitalization and death as primary endpoints, and only recently, some studies have included other WHF events regardless of location of care. This article reviews the evolution of the WHF definition, highlights the importance of considering the onset of WHF as an event that marks a new phase of HF, summarizes the latest clinical trials investigating novel therapies, and outlines unmet needs regarding identification and treatment of WHF.