Ring-Like Scar Architecture and Arrhythmic Outcomes of Patients With Nondilated Left Ventricular Cardiomyopathy Treated With Ventricular Tachycardia Ablation

Background: Nondilated left ventricular cardiomyopathy (NDLVC) is characterized by an elevated arrhythmic burden and frequent presence of ring-like late gadolinium enhancement (RL-LGE) pattern. However, the arrhythmic substrate and outcomes after ventricular tachycardia (VT) ablations remain undefined. Objectives: This study sought to characterize the arrhythmogenic substrate using postprocessed cardiac magnetic resonance and assess VT recurrence after ablation in patients with NDLVC. Methods: Consecutive patients with NDLVC undergoing VT ablation at the Hospital Clínic of Barcelona were included. Results: Thirty-seven patients were included (age 44 years [IQR: 39-55]; 78% male; left ventricular ejection fraction 45% [IQR: 40-52]). RL-LGE was observed in 21 of 37 (57%) patients. Compared with patients without it, patients with RL-LGE had lower left ventricular ejection fraction (40% [38% to 45%] vs 51% [49% to 55%], P < 0.0001), greater scar burden (16.2% [12.7% to 20.0%] vs 5.4% [5.0% to 6.0%], P < 0.0001), larger number of arrhythmogenic conducting channels (3 [2-4] vs 1 [1-2], P < 0.0001), and longer conducting channels (34 mm [29-38 mm] vs 12 mm [10-14 mm], P < 0.0001). Over a median of 3 years of follow-up, 30% of patients had VT recurrence with event rate of 10.2%/year. Dense scar (HR: 1.13, per 1% increment; 95% CI: 1.05-1.22; P = 0.002) and borderzone scar burden (HR: 1.27; 95% CI: 1.11-1.45; P = 0.001), number (HR: 2.35; 95% CI: 1.42-3.91; P = 0.001) and the length of conducting channels (HR: 1.04 per 1 mm increase; 95% CI: 1.01-1.06; P = 0.006) were associated with VT recurrence. The adjusted risk of VT recurrence was 24-fold higher in patients with RL-LGE (HR: 24.0; 95% CI: 2.8-207.1; P = 0.004). Conclusions: RL-LGE identifies patients with NDLVC with a more complex arrhythmogenic substrate and a poorer outcome after VT ablation.