The P wave duration in patients with atrial fibrillation undergoing cryoballoon pulmonary vein isolation. Preliminary results

Abstract

The pulmonary vein isolation remains the major target of atrial fibrillation ablation. The cryoablation lesions in the left atrium are supposed to disconnect the pulmonary vein from the atrium on the atrial side of the orifices. We hypothesized that the cryoballoon pulmonary vein isolation could result in the prolongation of the P wave duration. The aim of the study was to assess the duration of the P wave in 12-lead electrocardiogram and the influence of pulmonary vein isolation on this parameter. The study group included 21 patients (11 women and 10 men) 66.2+/-7.4 years of age undergoing cryoballoon ablation. In order to measure the P wave duration, we used the constant acquisition of electrogram and the electrocardiographic channels provided by LABSYSTEM™ Pro EP Recording System (Boston Scientific), magnifying the leads 64x. We calculated the duration in the simultaneously recorded 12-lead ECG, from the beginning of the earliest recorded P wave deflection, until the end of the latest P-wave deflection recorded in any lead. The P wave duration in the entire study group was 141.7+/- 12.5 ms before the ablation and increased significantly to 151.1+/-11.5 ms (p<0.05) after the procedure. The respective values in women were 144.1+/-4.3 vs. 156.0+/-4.7 ms (p<0.01) and 139.1+/-4.6 vs. 145.6+/-4.5 ms in men (p<0.05). The mean standard deviation of every single measurement considered separately was 4.4+/- 2.1 ms before the cryoablation and 4.6+/-1.8 ms after the procedure (p= not significant (n.s).), indicating very good reproducibility of the measurements. We concluded, that cryoballoon pulmonary vein isolation leads to the prolongation of the measured P wave duration. It seemed to result from conduction disturbances created by cryoablation. The clinical significance of the observed changes remains unknown.