Unmasking High-Output Heart Failure: Beyond Conventional Paradigms

Heart failure (HF) poses a significant medical challenge, affecting millions of adults in the United States. High-output heart failure (HOHF) is a distinct subtype characterized by elevated cardiac output exceeding 8 L/min or a cardiac index >4 L/min/m². Patients with HOHF often present similarly to those with heart failure with reduced ejection fraction and heart failure with preserved ejection fraction. However, the underlying pathophysiology differs; triggered by a progressive decline in systemic vascular resistance, the ensuing elevation of cardiac output eventually leads to left ventricular remodeling and HF. Failure to differentiate HOHF from other variant forms of HF has implications for management, particularly relating to the use of vasodilator medications with potentially deleterious consequences, ensuing from the unrestrained adoption of societal guideline-directed medical therapy recommendations. Despite its clinical importance, HOHF remains under-examined in literature, with limited recognition and understanding among clinicians. This review aims to provide a comprehensive analysis of knowledge surrounding HOHF, exploring its definition, etiopathology, and underlying pathophysiological mechanisms. Recognizing the challenges in diagnosing HOHF, we propose a novel diagnostic algorithm tailored to address the subtleties of this often-misdiagnosed variant of HF.