Clinical impact of mapping strategies for treatment of ventricular tachycardias in patients with structural heart disease

Background Substrate-based catheter ablation (CA) can be applied to more complicated cases such as hemodynamically unstable ventricular tachycardia (VT). We aimed to compare the efficacy between substrate-based and activation/entrainment-based ablation. Methods We investigated 85 consecutive patients (62 male, 53 ± 16 years) who underwent CA of VT to analyze the relationship between the ablation strategy and clinical outcome. The patients included 34 individuals with arrhythmogenic right ventricular cardiomyopathy, 16 with ischemic heart disease, 14 with dilated cardiomyopathy, 11 with sarcoidosis, and 10 with other heart diseases. The primary strategy was activation/entrainment mapping (Group-AE, N = 35); otherwise, substrate-based strategy was adopted (Group-S, N = 50) because of non-inducibility of VT or hemodynamic instability. Successful CA was defined as the non-inducibility of any VT at the end of the procedure in those with inducible clinical VT before ablation, and substrate elimination in those without. Results There were no significant differences in the left ventricular function, percentage of implantable cardioverter-defibrillator implantations, results of CA, and number of radiofrequency applications between Group-S and Group-AE. During 5 years of follow-up, there were no significant differences in sustained VT recurrences (15/50 vs. 15/35, P = 0.22), and cardiac death (2/50 vs. 3/35, P = 0.38). In patients with inducible VT before ablation, the elimination of the VT inducibility was associated with a lower recurrence rate (12/47 vs. 16/26, P = 0.003). Conclusions The substrate-based strategy adopted as an alternative option when the activation/entrainment-based strategy was unable to be performed resulted in a comparable VT recurrence rate. The extinction of VT inducibility achieved a favorable prognosis in structural heart disease patients.