The feasibility and safety of substrate modification on the left atrial roof area using a cryoballoon in atrial fibrillation ablation

Background: Data on additional substrate modification using a cryoballoon beyond cryoballoon pulmonary vein isolation (CB-PVI) is limited. We sought to evaluate the efficacy and safety of substrate modification on the left atrial roof area using CBs (LAR-CBs) for atrial fibrillation (AF) patients. Methods: Eighty-one AF patients (70.0[62.5-77.0] years, 33 paroxysmal AF[PAF], 48 non-PAF) underwent LARCBs following CB-PVIs. Voltage maps were created with a high-resolution mapping system. Roof line conduction block was evaluated during the repeat procedure. Results: The total number of applications for the CB-PVI and LAR-CB were 5.0 +/- 1.2 and 3.8 +/- 0.7, and both were significantly greater in non-PAF than PAF patients. LA roof areas had continuous scar in 61/79(77.2%) patients, and the mean balloon temperature was significantly lower in patients with continuous scar than those without (-39.3 +/- 3.8 vs. -36.0 +/- 4.6 degrees C, p = 0.004). The single procedure 1-year AF freedom was 87.6% (7.5% on antiarrhythmic drug) and was similar between PAF and non-PAF patients (p = 0.14). Twelve (14.8%) patients underwent a second procedure 5.5(2.2-7.5) months later, and a mean of 1.3 +/- 0.5 PVs were reconnected in 7/12 (58.3%) patients. Electrical conduction block across the roof line was proven in 3/12(25.0%) patients. There were 6(7.4%) complications related to the procedures, including iatrogenic roof dependent atrial tachycardia, takotsubo cardiomyopathy, and severe pericarditis in 1, 1, and 2 patients, respectively. Conclusions: LA roof area substrate modification using CBs yielded a high arrhythmia freedom after single procedures. However, a low incidence of electrical conduction block across the line during the chronic phase and delayed complications were the major concerns.