LAUSR

Catheter ablation for the treatment of ventricular tachycardia (VT) has been shown to reduce arrhythmia events, electrical storm, and recurrent device therapies, and successful ablation has been associated with improved survival in patients with structural heart disease (SHD) [1]. Reported success rates of VT ablation vary widely, owing in part to heterogeneous extent and distribution of arrhythmia substrate. To address this challenge, epicardial ablation is pursued with increasing frequency. Epicardial ablation, which can be associated with a higher risk of complications [2], has been studied most extensively in Chagas disease and in arrhythmogenic right ventricular dysplasia, where an endocardial-epicardial (endo-epi) approach has been shown to have a high procedural success rate and low incidence of recurrences [3, 4]. Studies comparing the clinical outcomes between endo-epi and endo ablation alone in ischemic heart disease (IHD) and dilated cardiomyopathy have generally been limited by small sample sizes and/or observational study design, yielding inconsistent findings—some (including a large meta-analysis) have shown that the addition of epicardial ablation is associated with higher freedom from VT and lower mortality, while others suggest no significant difference [5–10]. In the current issue of the Journal of Interventional Cardiac Electrophysiology, Matos et al. compare the longterm outcomes of two VT ablation strategies [11]. One strategy was termed “combined endo-epicardial ablation” (C-ABL) and included both endocardial and epicardial ablation, though the two portions could be done sequentially at separate procedures. The other strategy was termed “non-combined ablation” (NC-ABL) and included either endocardial or epicardial ablation alone. Of the 316 consecutive patients with drug-refractory, scar-based VT referred for ablation at two institutions, 53 (17%) underwent C-ABL, usually with separate endocardial and epicardial procedures, and 263 (83%) underwent NC-ABL, predominantly with endocardial ablation alone. Over a mean follow up of 3 years, VT-free survival was better and overall mortality lower in the C-ABL group. In sub-group analysis, the improved outcomes were only apparent in patients who had undergone a prior ablation procedure, representing about one-third of the overall population. Electrical storm at presentation and more advanced heart failure class were associated with an increased risk of VT recurrence and mortality. In a propensity score sensitivity analysis of two groups matched by factors including age, ejection fraction, NYHA functional class, and type of cardiomyopathy, the “combined” approach remained significantly associated with lower rates of VT recurrence among patients with prior ablation. Overall procedural complication rates were similar between the two ablation strategies, though the C-ABL strategy was associated with significantly more right ventricular punctures and pericardial effusions. The authors should be commended for the extensive data collection and analyses performed, both of which add to our existing knowledge by leveraging a relatively large patient cohort with long-term follow-up. The use of propensity score matching, which yielded two groups of 43 patients each from the C-ABL and NC-ABL strategies that were well matched on several important baseline variables, is another important step toward adjusting for the potential confounders inherent in an observational study design. The suggestion of survival benefit with the addition of eventual endocardial and epicardial mapping and ablation in patients with recurrent VT after a previous ablation is certainly intriguing. * Joshua D. Moss [email protected]