Stepwise Approach for Ventricular Tachycardia Ablation in Patients With Predominantly Intramural Scar

Abstract

Objectives: The goal of this study was to assess the value of a stepwise, image-guided ablation approach in patients with cardiomyopathy and predominantly intramural scar.

Background: Few reports have focused on catheter-based ventricular tachycardia (VT) ablation strategies in patients with predominantly intramural scar.

Methods: The study included patients with predominantly intramural scar undergoing VT ablation. A stepwise strategy was performed consisting of a localized ablation guided by conventional mapping criteria followed by a more extensive ablation if VT remained inducible. The extensive ablation was guided by the location and extent of intramural scarring on delayed enhanced-cardiac magnetic resonance imaging. A historical cohort who did not undergo additional extensive ablation was identified for comparison. A novel measurement, the scar depth index (SDI), indicating the percent area of the scar at a given depth, was correlated with outcomes.

Results: Forty-two patients who underwent stepwise ablation (median age 61 years [interquartile range: 55 to 69 years], 35 male patients, median left ventricular ejection fraction 36.0% [25.0% to 55.0%], ischemic [n = 4] or nonischemic cardiomyopathy [n = 38]) were followed up for a median of 17 months (8 to 36 months). A stepwise approach resulted in a 1-year freedom from VT, death, or cardiac transplantation of 76% (32 of 42). Patients who underwent additional extensive ablation had a lower risk of events than a clinically similar historical cohort (N = 19) (hazard ratio: 0.30; 95% CI: 0.13 to 0.68; p < 0.004). SDI_>5mm was associated with worse long-term outcomes (hazard ratio: 1.03; 95% CI: 1.01 to 1.06%; p = 0.03), SDI_>5mm >16.5% was associated with failed ablation (area under the curve: 0.84; 95% CI: 0.71 to 0.97).

Conclusions: Stepwise ablation using delayed enhanced-cardiac magnetic resonance guidance is a novel approach to VT ablation in patients with predominantly intramural scarring. The SDI correlates with immediate procedural and long-term outcomes.

Keywords: cardiac magnetic resonance; cardiomyopathy; catheter ablation; delayed enhancement; intramural scar; radiofrequency ablation; ventricular tachycardia.