Safety and efficacy of bipolar radiofrequency catheter ablation in ventricular arrhythmias of mural vs non-mural origin

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND: Bipolar radiofrequency catheter ablation (B-RFA) has shown promising results in refractory ventricular arrhythmia (VA) of septal origin and underlying non-ischemic cardiomyopathy (NICM). However, its efficacy and safety in other locations such as the free wall and papillary muscles (PM) has not yet been fully determined. PURPOSE: To describe and analyse the procedural data, safety and efficacy results of B-RFA in a cohort of patients with VA of different locations and underlying substrate. METHODS: We enrolled 21 patients with recurrent VA after prior failed ablation into this study, of whom 16 patients required B-RFA for effective ablation. Seven of the patients had ventricular ectopy (VE) and 9 presented with ventricular tachycardia (VT). During B-RFA, a contact-force-sensing, saline-irrigated catheter was connected to the ablation catheter connection on the radiofrequency generator and a second ablation catheter (saline-irrigated in 6 of the cases) was connected to the ground patch terminal through a custom-made switch box. This allowed visualization of both catheters on the 3D mapping system and acquisition of electrograms from both simultaneously. Procedure data, related complications and acute and long-term outcomes during follow-up were assessed. RESULTS: The VA distribution was septal (31.3%, n=5), PM (31.3%, n=5), right ventricle free wall (18.8%, n=3), left ventricle (LV) free wall (12.5%, n=2) and LV summit (6.3%, n=1). Compared to septal ablation, contact force obtained during B-RFA ablation was significantly lower in PM ablation (p=0.01), as was the impedance drop (p=0.03). There were no significant differences in the number of energy applications, their mean duration, the total ablation time, the power and the temperature among locations. Acute success was achieved in 15 patients (93.6%). Long-term success, defined as no recurrence of sustained VT or less than 1% VE burden on 24-hour Holter at 12-month follow up, was achieved in 11 patients (68.8%), and another 2 patients (12.5%) had partial success. Papillary muscle VA had lower acute and long-term success (80% and 60%, respectively) after B-RFA. On the other hand, patients with NICM appeared to have superior outcomes (figure 1). No steam pops or major peri-procedural complications were observed. However, the use of a non-irrigated indifferent electrode resulted in char formation. CONCLUSIONS: B-RFA can be used successfully and safely in NICM involving the septum and free walls but has limited use for PM arrhythmias. This could be related to a lack of catheter stability and reduced energy transfer. In addition, when using B-RFA, any catheter in the circulatory system should be irrigated. [Figure: see text]