Importance of a successful ablation of all clinical VT isthmuses
Previous randomized multicenter trials have shown that substate ablation reduces any VT recurrences during the follow-up as compared to targeting only a clinical and stable VT, making substate ablation a basic strategy for VT ablation.14-16 In the present study, the identification and RF ablation of the clinical VT isthmus in addition to a substate ablation was shown to be associated with fewer VT recurrences. Hadjis et al. reported that the identification of the VT isthmus in addition to a substate ablation significantly reduced the recurrence rate (HR 0.21, 95% CI: 0.07-0.63, P < 0.01).17 Cano et al. also reported that a baseline inducibility of greater than 1 VT morphology was an independent predictor of VT recurrence (HR 12.05, 95% CI: 1.60-90.79, P = 0.02) and complete activation mapping was associated with a reduction in the VT recurrence.18
In this study, patients in whom VT non-inducibility could not be achieved at the end of the RF ablation were included, so in many cases, VT was induced with or without hemodynamic stability at the end of the RF ablation. Nevertheless, a successful ablation of all clinical VT isthmuses was correlated with non-recurrence, suggesting that the identification of the VT isthmus is important in addition to the basic strategy of substate ablation.