One-year clinical success of a ‘no-bonus’ freeze protocol using the second-generation 28 mm cryoballoon for pulmonary vein isolation

Abstract

Studies on the use of the second-generation 28 mm cryoballoon (CB) for the treatment of atrial fibrillation (AF) have reported superior 1-year clinical outcome. Customarily, a bonus freeze cycle is applied after pulmonary vein isolation (PVI). The purpose of the present study was to assess the 1-year clinical outcome following PVI foregoing a bonus freeze cycle. Patients with drug-refractory paroxysmal AF (PAF) or persistent AF underwent PVI using the second-generation 28 mm CB. The freeze cycle duration was set at 240 s. No bonus freeze cycle was applied. Clinical follow-up (FU) included 12-lead ECGs and 24h-Holter ECGs at 3, 6, and 12 months. A total of 45 patients (age 60 ± 11 years, mean LA diameter 42.1 ± 8.6 mm, n = 38 [84%] PAF) underwent CB-based PVI. Of 177 pulmonary veins (PVs) identified, 176/177 (99%) PVs were successfully isolated. The mean number of CB applications was 1.2 ± 0.4, 1.5 ± 0.8, 1.4 ± 0.7, 1.1 ± 0.3 and 1.7 ± 1.2 for the right superior PVs, right inferior PVs, left superior PVs, left inferior PVs, and left common PVs, respectively. Mean procedure and fluoroscopy times were 113 ± 32 and 19 ± 7 min, respectively. Phrenic nerve palsy occurred in 1/45 (2%) patients. One of 45 (2%) patients was lost to FU. After a mean FU period of 392 ± 58 (267–522) days including a 3-month blanking period, 36 of 44 (82%) patients remained in stable sinus rhythm. Five out of eight patients with arrhythmia recurrence underwent a second procedure. Only those PVs isolated with a single freeze cycle (5/11 PVs, 45%) demonstrated PV reconduction. In contrast, no PV reconnection was found in PVs initially treated with multiple freeze cycles. A ‘no-bonus’-freeze protocol for PVI using the second-generation 28 mm CB resulted in an 82% 1-year clinical success rate. A bonus freeze cycle following successful PVI may not be essential to superior clinical outcome.