心不全（EF保持型）における非侵襲的圧力-容量ループ解析から得られる潜在エネルギーの予後価値

Heart failure with preserved ejection fraction (HFpEF) is characterized by impaired relaxation and increased stiffness, leading to elevated filling pressures and inefficient cardiac performance despite preserved ejection fraction (LVEF ≥ 50%). These changes alter pressure-volume (PV) loop profiles. Noninvasive PV loop analysis using cardiovascular magnetic resonance (CMR) and brachial cuff pressure offers a novel approach to evaluating ventricular energetics. This study aimed to assess the prognostic value of CMR-derived PV loop parameters in HFpEF. Patients with HFpEF confirmed by invasive cardiopulmonary exercise testing who underwent CMR were included. PV loop parameters-including potential energy (PE), stroke work (SW), ventricular efficiency (VE), external power, and energy per ejected volume-were derived from CMR cine imaging and brachial cuff pressure measurement. The primary outcome was a composite of cardiovascular death and heart failure hospitalization. Associations were assessed using multivariable Cox proportional hazards models. Between February 2017 and August 2021, 161 patients (median age 55.1 years; 42.9% female) were enrolled. Nineteen (11.8%) experienced the primary endpoint over a median follow-up of 1.63 years. In unadjusted analysis, PE and VE were significantly associated with events (P < 0.05). In multivariable models adjusting for age, sex, hypertension, diabetes, hematocrit, and SW, PE remained an independent predictor (HR 3.59, 95% CI 1.24-10.42, P = 0.02). Noninvasive PV loop analysis using CMR and brachial cuff pressure identifies PE as a novel predictor of cardiovascular events in HFpEF, emphasizing impaired ventricular energetics as a key mechanism.