Splitting the P-Wave: Improved Evaluation of Left Atrial Substrate Modification after Pulmonary Vein Isolation of Paroxysmal Atrial Fibrillation

Atrial substrate modification after pulmonary vein isolation (PVI) of paroxysmal atrial fibrillation (pAF) can be assessed non-invasively by analyzing P-wave duration in the electrocardiogram (ECG). However, whether right (RA) and left atrium (LA) contribute equally to this phenomenon remains unknown. The present study splits fundamental P-wave features to investigate the different RA and LA contributions to P-wave duration. Recordings of 29 pAF patients undergoing first-ever PVI were acquired before and after PVI. P-wave features were calculated: P-wave duration ([Formula: see text]), duration of the first ([Formula: see text]) and second ([Formula: see text]) P-wave halves, estimating RA and LA conduction, respectively. P-wave onset ([Formula: see text]) or offset ([Formula: see text]) to R-peak interval, measuring combined atrial/atrioventricular and single atrioventricular conduction, respectively. Heart-rate fluctuation was corrected by scaling. Pre- and post-PVI results were compared with Mann–Whitney U-test. [Formula: see text] was correlated with the remaining features. Only [Formula: see text] (non-scaling: [Formula: see text] , [Formula: see text] , scaling: [Formula: see text] , [Formula: see text]) and [Formula: see text] (non-scaling: [Formula: see text] , [Formula: see text] , scaling: [Formula: see text] , [Formula: see text]) were decreased. Correlation of all features with [Formula: see text] was significant before/after PVI ([Formula: see text]), showing the highest value between [Formula: see text] and [Formula: see text] ([Formula: see text]). [Formula: see text] correlated more with [Formula: see text] ([Formula: see text] 0.540–0.805) than [Formula: see text] ([Formula: see text] 0.419–0.710). [Formula: see text] shortening after PVI of pAF stems mainly from the second half of the P-wave. Therefore, noninvasive estimation of LA conduction time is critical for the study of atrial substrate modification after PVI and should be addressed by splitting the P-wave in order to achieve improved estimations.