P308Efficacy and safety of bipolar ablation for the treatment of Ventricular Tachycardia deep substrates

Abstract

Background: Ablation of septal Ventricular Tachycardia (VT) may be quite challenging because of myocardial thickness often prevents effective lesion formation. Bipolar ablation has been proven to be more effective than unipolar in animal models. Purpose: To report efficacy and safety of bipolar ablation in the setting of VT related to structural heart disease and intramural substrates. Methods and Results: Sixteen patients (pts 13/16 males: 81.2%) with VT related to septal intramural substrate [14/16 pts(87.5%) with dilated cardiomyopathy (DCM) 2 pts(22.5%) with Hypertrophic Cardiomyopathy (HCM)]were randomized to either bipolar Radiofrequency Catheter Ablation (B-RFCA) or unipolar ablation (U-RFCA). Mean age was 6765.1 ys mean LVEF was 3866 %. Mean VT CL 342636 msec. Unipolar ablation was performed in 7/16 pts (43.7%) from both side of the interventricular septum (max power setting on the right IV septum: 50 W, max power setting on the left IV power setting 60 W) to treat at least 1 septal VT morphology concomitant ablation on the LVOT was necessary in 6/7 pts (85.7%) because of the induction of antero-basal LV-VT morphologies. In B-RFCA group (9/16 pts, 56.3%), ablation was delivered between 2 ablation catheters facing the opposite side of the IV septum in 7/9 pts (77.8%) in other two patients RF was delivered between RVOT-LVOT (1 pt) and between left coronary cusp and subaortic antero-basal LVOT (1 pt). Mean distance from the ablation catheter tips at the effective ablation site was 9.561.7 mm. Additional unipolar lesions to treat LV latero-basal VT morphology were required in 1 patient. In one patient B-RFCA was not attempted because the thickness of IV septum was deemed to be unsafe (6 mm). Prevention of any VT inducibility was achieved in 5/7 pts of U-RFCA group (71.4%) and in 8/9 pts in the B-RFCA group (88.9%). Cardiac tamponade was reported in 1 out of the 9 B-RFCA pts (11.1%) who had undergone RVOT-LVOT ablation. On the mean follow-up time of 762 months, VT recurrence was documented in 3/7 U-RFCA group (42.8%) and in 1/9 pts in B-RFCA group (11.1%). Conclusions: Bipolar ablation appears to be an effective and safe treatment for VT ablation related to deep substrates.