P wave polarity during pacing in pulmonary veins

Introduction: Recent studies have demonstrated that premature depolarizations that trigger atrial fibrillation often arise in pulmonary veins. The purpose of this study was to evaluate whether P wave polarity is helpful in distinguishing which of the 4 pulmonary veins is the site of orgin of a premature depolarization. Methods and Results: In 28 patients without structural heart disease who underwent focal ablation of paroxysmal atrial fibrillation, P wave polarity on a 12-lead electrocardiogram (ECG) was analyzed during sinus rhythm, and during pacing at a cycle lengh of 500-600 ms in the high right atrium and within each of the 4 pulmonary veins. P waves were categorized as positive, negative, biphasic or isoelectric. A negative or biphasic P wave in lead I (sensitivity 85%, specificity 71%) or a positive P wave in V1 (sensitivity 85%, specificity 89%) were helpful in predicting a pulmonary venous site of origin as opposed to a right atrial site of origin. A positive P wave in lead II and III distinguished superior from inferior pulmonary veins (sensitivity 90%, specificity 84%). The sensitivity and specificity of negative or biphasic P waves in lead aVL in distinguishing a left from right pulmonary vein site of origin were 94% and 42%, respectively. Conclusions: Analysis of P waves polarity may be helpful in localizing the pulmonary vein that is the site of origin of a premature depolarization. Among the 12 ECG leads, I, II, III, aVL, and V1 are the most helpful in regionalizing premature depolarizations arising in the pulmonary veins.