Arrhythmic risk prediction in non-dilated left ventricular cardiomyopathy: The role of overlap with arrhythmogenic cardiomyopathy

Background: Non-dilated left ventricular cardiomyopathy (NDLVC) has been defined as non-ischemic LV scarring or fatty replacement regardless of global or regional wall motion abnormalities, or isolated global LV hypokinesia without scarring. We evaluated the arrhythmic risk in NDLVC and assessed the prognostic value of overlapping features with arrhythmogenic cardiomyopathy (ACM). Methods: All patients who underwent cardiovascular magnetic resonance (CMR) scan and genetic testing between 2012 and 2022 and met the diagnostic criteria for NDLVC were selected. All patients were evaluated for the presence of the 2024 diagnostic criteria for ACM. The primary endpoint was a composite of sudden cardiac death (SCD), ventricular fibrillation (VF) or sustained ventricular tachycardia (VT),. Results: The cohort included 225 patients (35 % women, median age 55 years [interquartile range 44–64]). The etiology was genetic in 44 % of cases, with 51 pathogenetic/likely pathogenetic (P/LP) variant and 49 variant of uncertain significance (VUS). Over 3.3 years (1.5–6.0), 12 patients (5 %) developed an endpoint event. The risk increased in patients meeting the criteria for definite or borderline arrhythmogenic left ventricular (ALVC) and biventricular (ABVC) cardiomyopathy. In the whole cohort, LGE >9 % of LV mass was the most significant predictor of outcome. In patients with LGE >9 %, fatty replacement significantly increased the risk of arrhythmic events. Conclusions: LGE >9 % of LV mass and fatty replacement are associated with an increased arrhythmic risk in NDLVC. The risk is also higher if patients meet the 2024 criteria for definite or borderline ALVC/ABVC.