Bipolar radiofrequency ablation for ventricular tachycardias originating from the interventricular septum: Safety and efficacy in a pilot cohort study

BACKGROUND Interest has grown in recent years in bipolar radio frequency ablation (B-RFA). However, indications and outcome in patients with ventricular tachycardia (VT) are still to be defined. OBJECTIVE The purpose of this study was to describe patient selection, safety and effectiveness of B-RFA, in a pilot cohort study of patients with nonischemic dilated cardiomyopathy (NIDCM) and drug-refractory VT. METHODS We enrolled 21 patients with NIDCM (mean age 6610 years; 18/21 (86%) men; left ventricular ejection fraction 35%14%; 100% redo procedures) scheduled for a B-RFA procedure because of drug-refractory VT of suspected septal (interventricular septum [IVS]) origin. After electroanatomic mapping by using the CARTO (R) 3 system, B-RFA was performed in all patients. Short and long-term outcomes, including procedural success, major complications, and occurrence of major ventricular arrhythmias (MVAs), were evaluated at 25 +/- 8 months of follow-up (FU). RESULTS Endocardial mapping showed IVS scar in all patients and extra-IVS in 7 patients (33%). B-RFA was performed at an average power of 33 W, for 60-90 seconds, over a 4.1 cm(2) area, with 13 +/- 3 mm distance between catheters tips. The impedance drop was 27 +/- 4 U. The primary end point of noninducibility of the target clinical VT was obtained in 20 patients (95%). During FU, MVAs were documented in 7 patients (33%). FU MVAs occurred in all (100%) patients with extra-IVS localizations (7 of 7) or inflammatory nonischemic cardiomyopathy etiology (2 of 2). IVS thinning (tip-to-tip catheter distance < 5 mm) represented the only anatomical limitation to B-RFA. CONCLUSION B-RFA is feasible in patients with NIDCM and drug refractory VT of septal origin. Extra-IVS substrate and inflammatory NIDCM etiology were associated with an adverse outcome.