P wave polarity during pacing in pulmonary veins

Introduction: Recent studies have demonstrated that premature depolarizatio ns that trigger atrial fibrillation often arise in pulmonary veins. The pur pose of this study was to evaluate whether P wave polarity is helpful in di stinguishing which of the 4 pulmonary veins is the site of orgin of a prema ture depolarization. Methods and Results: In 28 patients without structural heart disease who un derwent focal ablation of paroxysmal atrial fibrillation, P wave polarity o n a 12-lead electrocardiogram (ECG) was analyzed during sinus rhythm, and d uring pacing at a cycle lengh of 500-600 ms in the high right atrium and wi thin each of the 4 pulmonary veins. P waves were categorized as positive, n egative, 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 i n lead II and III distinguished superior from inferior pulmonary veins (sen sitivity 90 %, specificity 84 %). The sensitivity and specificity of negati ve or biphasic P waves in lead aVL in distinguishing a left from right pulm onary 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. Am ong the 12 ECG leads, I, II, III, aVL, and V1 are the most helpful in regio nalizing premature depolarizations arising in the pulmonary veins.