Clinical characterization and prognostic assessment of patients with left ventricular ring-like scar

Background: Left ventricular (LV) ring-like (RL) scar is a cardiac magnetic resonance (CMR)-defined entity reflecting a spectrum of underlying causes. This study focused on cardiomyopathy-related RLs, aiming to characterize genotype-phenotype associations and assess long-term prognosis. Methods: Multicentre, retrospective, observational study including patients with non-ischemic LV RL scar ( ≥3 contiguous segments with subepicardial or midwall late gadolinium enhancement in the same short-axis plane), plus one of: a likely pathogenic/pathogenic (LP/P) variant; confirmed family history; borderline/definitive arrhythmogenic cardiomyopathy per 2024 European Task Force criteria. The primary endpoint were major arrhythmic events (MAEs), a composite of sudden cardiac death (SCD), aborted SCD, appropriate implantable cardioverter-defibrillator (ICD) interventions, and sustained ventricular tachycardia. Results: The study included 343 cardiomyopathy-related RLs (median age 46 years, 40% female), 47% with dilated cardiomyopathy (DCM) and 53% with non-dilated LV cardiomyopathy (NDLVC). Patients differed significantly according to phenotype and genetic subgroup. Median follow-up was 3.5 years; at 10 years, 70 MAEs occurred (4.970 per 100 patient-years). Multivariable predictors of MAEs included male sex (HR 2.061, 95% CI 1.113–3.813, p=0.021), syncope (HR 4.032, 95% CI 1.784–9.114, p=0.001), lateral fragmented QRS (HR 2.467, 95% CI 1.221–4.986, p=0.012), LVEF (HR 0.958, 95% CI 0.936–0.981, p<0.001), and moderate-severe RV dysfunction (HR 2.077, 95% CI 1.122–3.845, p=0.020). The RL-MAE risk score was derived from these multivariable predictors and stratified patients into four groups correlating with 5-year arrhythmic risk; internal validation showed C-statistic 0.710 and calibration slope 0.920. Conclusions: Cardiomyopathy-related RLs encompass both DCM and NDLVC with complex genetic backgrounds. Arrhythmic risk is substantial, and the RL-MAE score provides a multiparametric tool for personalized risk stratification and management