Arrhythmic risk stratification in patients with left ventricular ring-like scar

AIMS: Left ventricular (LV) ring-like scar on cardiac magnetic resonance (CMR) has been linked to malignant arrhythmias in patients with non-ischaemic cardiomyopathy. This study aimed to perform a comprehensive evaluation of this phenotype and to identify risk factors for life-threatening arrhythmic events (LAEs), a composite of sudden cardiac death (SCD), aborted SCD, and sustained ventricular tachycardia. METHODS AND RESULTS: One hundred and fifteen patients [median age 39 (interquartile range, IQR, 28-52), 42% females] were identified at 6 referral centres. Inclusion criteria were ring-like LV scar [≥3 contiguous segments with sub-epicardial/midwall late gadolinium enhancement (LGE) in the same slice] and one among: pathogenic/likely pathogenic genetic variant, family history for cardiomyopathy, or arrhythmogenic cardiomyopathy diagnosis. During the study follow-up, survival free from LAEs was 60% (3.8 events/100 patients/year); at a median follow-up of 4.6 years (IQR 1.7-8.4) it was 84%. On multivariable analysis, anterior Q waves [hazard ratio (HR): 1.030, 95% confidence intervals (CI): 1.014-1.046, P < 0.001], QRS width (HR: 4.642, 95% CI: 1.296-16.628, P = 0.018), and LV end-diastolic volume index (LVEDVi; HR: 1.011, 95% CI: 1.001-1.021, per mL/m2 increase, P = 0.040) were independently associated with LAEs; with good discrimination power (Harrell's C-index = 0.796). Three risk categories were identified: normal electrocardiogram (ECG), abnormal ECG and no LAEs predictive variables, abnormal ECG and ≥1 LAEs predictive variables, with a decreasing survival from 100 to 65% and 49%, respectively (Log-rank test = 0.015). CONCLUSION: In this study, the LV ring-like scar phenotype was associated with a high rate of malignant arrhythmias in presence of anterior Q waves, QRS prolongation, and increased LVEDVi. A normal ECG identified a lower risk sub-group.