A prognostically meaningful definition of non-dilated left ventricular cardiomyopathy.

Non-dilated left ventricular cardiomyopathy (NDLVC) has been defined as non-ischemic LV scarring and/or fatty replacement and/or hypokinesia, without LV dilation. We tried to identify specific criteria for LV dilation and dysfunction to implement this definition. We identified all non-ischemic cardiomyopathy patients undergoing a cardiovascular magnetic resonance scan from 2012 to 2022 with LV ejection fraction (LVEF) < 55% and/or non-ischemic late gadolinium enhancement (LGE) and/or fatty replacement, and without specific etiologies. The primary endpoint was a composite of all-cause death, sustained ventricular tachycardia or fibrillation. The cohort included 388 patients (32% women, median age 55 years [interquartile range 43-63]). Over 4.3 years (1.9-7.0), 59 patients (15%) developed a primary endpoint event. The risk increased exponentially with LVEDVi values, with inflection points approaching the upper reference limit of LVEDVi (< 96 mL/m in women, < 105 mL/m in men). Using these criteria, we identified NDLVC in 237 patients (61%). Among them, LVEF was the only univariate predictor of outcome. Patients with LVEF ≥ 45% (n = 212) or ≥ 40% (n = 223) had a longer survival than those with LVEF < 45% or < 40% (p = 0.025 and p < 0.001, respectively). NDLVC patients, identified by non-ischemic LV scarring and/or fatty replacement and/or hypokinesia and LVEDVi < 96 mL/m (women) or < 105 mL/m (men), have a lower risk of death or ventricular arrhythmias than patients with dilated cardiomyopathy. LVEF < 45% or < 40% further stratified outcome. The definition of NDLVC could incorporate these LVEDVi and LVEF cut-points to identify a population of patients with a homogeneous risk of death or ventricular arrhythmias.