Optimal cut off point of LVEF value using cardiovascular magnetic resonance for prognostic stratification in end stage hypertrophic cardiomyopathy

Abstract Background In hypertrophic cardiomyopathy (HCM), end-stage disease is traditionally defined by a left ventricular ejection fraction (LVEF) below 50%. This threshold is widely used and supported by observational data linking it to increased mortality. However, this binary definition may oversimplify the continuum of systolic dysfunction and fail to accurately capture its prognostic significance. Purpose To determine the optimal cut-off point of LVEF for predicting long-term all-cause mortality in a large cohort of consecutive end-stage HCM patients. Methods We retrospectively analysed all patients referred for cardiovascular magnetic resonance (CMR) assessment of HCM at three French tertiary centres between 2008 and 2024. The primary endpoint was all-cause mortality, obtained from the French National Death Registry. A conditional inference tree (C-Tree) was applied to identify the optimal cut-off point of LVEF for predicting all-cause mortality. Cox proportional hazards models were used to assess the association between LVEF and mortality, adjusting for relevant clinical and imaging covariates: sex, age, BMI, hypertension, smoking status, diabetes, history of heart failure hospitalisation, history of atrial fibrillation, chronic kidney disease, right ventricular dysfunction and indexed end-diastolic volume. A restricted cubic spline model assessed the continuous relationship between LVEF and all-cause mortality, adjusted for covariates used in the Cox model. Results Among 2,875 eligible patients with HCM, we included 691 patients (mean age 53 ± 7 years, 54% male) with a LVEF