Lesion recovery, epicardial substrate, or new circuit? Exploring the dark side of recurrent ventricular tachycardia after endocardial ablation

Abstract

t g f b t t z h s Catheter ablation of ventricular tachycardia (VT) was first introduced into clinical practice as an experimental technique in 1983. Over the years, outstanding improvements in mapping and ablation techniques coupled with important technical innovations, such as the introduction of radiofrequency energy with open-irrigation platforms, have established catheter abation as an important treatment option for VT. Disturbingly, he long-term freedom from recurrent VT is still disappointing, ith nearly 50% of patients experiencing VT recurrence at ong-term follow-up. A correct understanding of the mechanisms leading to VT recurrence is crucial to develop new techniques and tools to improve the success rate. In this issue of HeartRhythm, Kosmidou et al report their experience with repeat procedure of recurrent postinfarction VT after a failed endocardial ablation. The authors retrospectively compared the baseline characteristics and procedural outcomes of 107 patients undergoing repeat ablation after a median of one (range 1–6) previous failed endocardial catheter ablation (PFCA) procedures, with a reference group of 173 patients who had a single catheter ablation (SCA) procedure in their institution between 1999 and 2010. The PFCA group had a higher prevalence of inferior and septal scars (P .001 for both comparisons) and required an endoepicardial procedure in 25% of cases (vs. 0% in the SCA group). Several important points arise from these data. First, although the association between scar location and effectiveness of endocardial ablation has not been thus far evaluated in a systematic fashion, previous reports are consistent with the findings by Kosmidou et al. Schmidt and colleagues assessed he incidence of epicardial substrates in patients with a PFCA. In this study, five (45%) of 11 patients with postinfarction VT had an inferior scar and no patient had a lateral scar. Similarly, Nakahara et al reported evidence of putative endoepicardial