The TWOSOME randomized trial: clinical outcome of single-tip versus single-shot pulsed field ablation for pulmonary vein isolation in paroxysmal atrial fibrillation

Abstract Background Non-thermal pulsed field ablation (PFA) is an emerging technology to perform pulmonary vein isolation (PVI) for atrial fibrillation (AF). Different PFA systems are available, but no comparative outcome data exist. Purpose Randomized trial to compare single-tip versus single-shot PFA for initial PVI in paroxysmal AF patients. Methods In this single-center trial, paroxysmal AF patients were prospectively enrolled and 1:1 randomized in the single-tip or single-shot PFA group. Single-tip PVI was performed using a PFA generator and a 3.5mm contact-force enabled ablation catheter guided by 3D mapping system. The pulsed electric field dosing was 25 Ampere (A) (anterior) and 22 A (posterior), respectively. In the single-shot PVI group, a 31 or 35mm pentaspline PFA catheter (2.0 kV) was used for fluoroscopy-guided PVI. In this interim analysis, acute efficacy, safety and clinical outcome were assessed. Results One hundred patients underwent PVI in conscious sedation (50 single-tip, 50 single-shot, 64 ± 10 years, 44% female, CHA2DS2-VA 2 [0-2]). There were no differences in baseline characteristics. Acute PVI was achieved in 100%. In the single-tip group, total procedure time was significantly longer (119 ± 30 min vs. 44 ± 11 min, p <0.001) and fluoroscopy time was significantly shorter (4 ± 2 min vs. 14 ± 5 min, p <0.001) as compared to the single-shot group. The overall complication rate was 6% and did not differ between the groups (p=0.67). In the single shot PFA group, 3 minor access site complications and one symptomatic cerebral air embolism following transseptal puncture (prior to insertion of the PFA system) occurred. Symptoms completely resolved during follow-up. In the single-tip group, 1 minor access site complication was detected and 1 pericardial tamponade requiring drainage resulted from coughing while no real-time visualization of the single-tip catheter was available. No permanent sequelae occurred. There were no PFA specific complications. At a median follow up of 9 months, the estimated arrhythmia-free survival was 80% in the single-shot group and 88% in the single-tip group, respectively (p=0.29). Conclusions In this interim analysis of a randomized trial, single-shot or single-tip PFA for PVI both demonstrated high acute efficacy and a promising 9 months clinical outcome. Procedural time was significantly longer in the single-tip PFA group. Non-availability of real-time visualization and contact-force information of the single-tip ablation catheter during energy application is a current technical limitation that could be associated with complications.