Anatomical characteristics of patients with difficulty in cryoablation of left superior pulmonary vein

Abstract

Objective In the cryoballoon ablation (CBA) procedure of atrial fibrillation (AF) , the anatomical variability of the pulmonary veins was an important factor influencing the procedural difficulty. This study was to investigate the anatomical factors that cause procedural difficulty in cryoablation of the left superior pulmonary vein (LSPV) . Methods From January 2017 to April 2018, a total of 826 patients with symptomatic AF who had undergone CBA using second-generation cryoballoon in the Fuwai Hospital were enrolled. According to the definition of LSPV cryoablation difficulty, LSPV needed to be cryoablation≥4 timesto achieve pulmonary vein electrical isolation, and the number of cryoablation accounted for more than 50% of the total number of pulmonary vein, 37 patients. LSPV was cryoablation once, and when the time of pulmonary vein isolation was less than 60 seconds, defined LSPV cryoablation easily, as a control group, 38 cases. The anatomical characteristics, such as whether LSPV was the left common pulmonary vein, diameter of veins, the distance between LSPV ostium to bifurcation, the thickness of ridge between LSPV and left atrial (LA) appendage, the angle between LSPV and LA roof-plane, were analyzed from pre-procedural cardiac computed tomography. Results In the patients with LSPV cryoablation difficulty, the incidence of left common pulmonary vein was higher (41% vs. 5%, P=0.001) . Furthermore the maximum and minimum diameter of veins were significantly larger than those in the control group[ (29.05±5.98) mm vs. (23.41±3.04) mm, P<0.001; (17.82±5.61) mm vs. (15.28±3.43) mm, P=0.020]. Compared to the control group, the thickness of ridge between LSPV and left atrial appendage was thinner[ (5.06±1.30) mm vs. (6.03±1.39) mm, P=0.003]and the angle between LSPV and LA roof-plane was small (23.81°±15.23°vs. 35.50°±12.11°, P<0.001) for thecryoablation difficult group respectively. Multivariate regression analysis showed that the thickness of ridge between LSPV and left atrial appendage and the angle between LSPV and LA roof-plane were highly related to the procedural difficulty (OR=1.677, 95%CI1.025-2.746, P=0.040; OR=1.086, 95%CI 1.019-1.157, P=0.011) . Conclusion During the CBA of atrial fibrillation, the thickness of ridge between LSPV and left atrial appendage was thinner and the angle between LSPV and LA roof-plane was smaller, CBA for LSPV was often more difficult. Key words: Atrial fibrillation; Left superior pulmonary vein; Cryoballoon ablation