Characteristics of Clinical and Induced Ventricular Tachycardia Throughout Multiple Ablation Procedures.

BACKGROUND: Optimal procedure endpoints of catheter ablation for ventricular tachycardia (VT) are not defined and multiple repeat procedures are sometimes required. However, there are few studies to compare the details of repeat procedures to the initial procedure. The aim of this study is to compare the characteristics of clinical and induced VT throughout multiple procedures and clarify their relations. METHODS AND RESULTS: Of 425 consecutive patients with structural heart disease who underwent catheter VT ablation, second, third and fourth procedures were performed in 101, 23, and 5 patients, respectively. Of 227 VTs that were induced during the second procedure, 68 (30%) VTs had previously been induced at the first procedure. In multivariable analysis, identification of an exit/isthmus site (HR = 0.29, P = 0.047), early termination of VT during radiofrequency application (HR 0.11, P = 0.037) and elimination of target VT at the end of first procedure (HR = 0.43, P = 0.036) were independently associated with noninducibility of the same VT at the second procedure. Over the course of multiple procedures the mean VT cycle length gradually lengthened (381 ± 107, 413 ± 111, 460 ± 124, 507 ± 99 milliseconds in first, second, third, and fourth procedure, respectively, P < 0.001) and more induced VTs became mappable (32%, 40%, 62%, and 70% in first, second, third, and fourth procedure, respectively, P < 0.001). CONCLUSIONS: Identification and ablation of VT exit/isthmus, early termination of VT during radiofrequency application and elimination of targeted VT are associated with absence of that VT during a repeat procedure, and recurrences are then mostly due to new VTs or other VTs that were not induced at the first procedure.