Correlation between asymptomatic gastroesophageal excessive transmural injury after pulmonary vein isolation and a bonus freeze protocol using the second-generation 28-mm cryoballoon for paroxysmal atrial fibrillation.

Background: Second-generation cryoballoon (2G-CB) ablation is highly effective for achieving pulmonary vein isolation (PVI) with a promising clinical outcome. However, the ideal freezing strategy for preventing gastroesophageal excessive transmural injury (ETI) remains under debate. This study aimed to clarify the correlation between gastroesophageal ETI and a bonus-freeze protocol after PVI using 2G-CBs.

Method: This study included 100 patients who underwent PVI using 2G-CB followed by an endoscopic examination. The freeze-cycle duration was set at 180s. In the first 33 patients a 120s bonus-freeze was applied after successful PVI (bonus group), while in the following 67 the bonus freeze was omitted (non-bonus group). Early freezing interruption was performed when the esophageal temperature reached 25°C. Gastroesophageal ETI was defined as any injury that resulted from the PVI, including esophageal damage or periesophageal nerve injury.

Results: Gastroesophageal ETIs were observed in 9 (27.3%) and 6 (9.0%) patients and were all asymptomatic, esophageal damage in 3 and 0, and periesophageal nerve injury in the remaining 6 and 6 in the bonus group and non-bonus group, respectively (p=0.033). In the multivariate analysis, the bonus freeze protocol (odds ratio 3.527; 95% confidence interval 1.110-11.208; p=0.033) was the sole independent predictor of gastroesophageal ETI. During a one-year follow-up 26 of 33 bonus group patients (78.8%) and 52 of 67 (77.6%) non-bonus group patients remained in stable sinus rhythm without any differences between the groups.

Conclusions: In the patients with a bonus-freeze protocol using the 2G-CB, gastroesophageal ETIs were detected more often than in those with the non-bonus freeze protocol. In contrast, freedom from atrial fibrillation after the 2G-CB based PVI was comparable when applying either a bonus or non-bonus freeze protocol.