Using computed tomogram atrial myocardial thickness maps in cryoballoon pulmonary vein isolation: The UTMOST AF II Randomized Clinical Trial

Abstract

Aims: Whether adjusting the duration of ablation based on left atrial wall thickness (LAWT) provides extra benefits for pulmonary vein (PV) isolation for atrial fibrillation (AF) is uncertain. We studied the safety and efficacy of tailored cryoballoon PV isolation (CB-PVI) based on LAWT for paroxysmal AF.

Methods and results: Two hundred seventy-seven patients with paroxysmal AF refractory to anti-arrhythmic drug were randomized 1:1 to either LAWT-guided CB-PVI (n = 135) and empirical CB-PVI (n = 142). Empirical CB-PVI was performed using a 28 mm cryoballoon with recommended application for 240 s per ablation. Cryoapplication in the LAWT-guided group was titrated (additional application for 120 s at PVs, where >25% of the circumference includes segments with LAWT > 2.5 mm and reduced baseline application to 180 s at PVs where >75% of the circumference includes segments with LAWT < 1.5 mm) according to the computed tomography LAWT colour map. The primary endpoint was freedom from any documented atrial arrhythmia of more than 30 s without antiarrhythmic medication, after a single ablation procedure. During a mean follow-up of 18.7 months, patients in the LAWT-guided CB-PVI group (70.8%) had a higher event-free rate from primary endpoint than those in the empirical CB-PVI group (54.4%; hazard ratio 0.64, 95% confidence interval 0.42-0.99; P = 0.043). No differences were observed between the groups in complication rates (3.0% in LAWT-guided vs. 4.9% in empirical CB-PVI). The total procedure time was extended in the LAWT group than in the empirical group (mean 70.2 vs. 65.2 min, respectively).

Conclusion: The LAWT-guided energy titration strategy improved freedom from atrial arrhythmia recurrence, compared with conventional strategy.