Electrocardiographic and electrophysiologic predictors of successful ablation site in patients with manifest posteroseptal accessory pathway

Background: Prediction of accessory pathway (AP) location before radiofrequency ablation has become increasingly important for patients with AP; this is especially true for posteroseptal (PS) APs. Objective: To identify electrocardiographic and electrophysiologic predictors of pathway location in patients with manifest posteroseptal AP. Methods: A detailed electrocardiographic analysis, electrophysiologic study, and ablation were performed in 94 patients with single manifest posteroseptal AP (mean age 35.0 ± 13.8 years; 56 males). Results: Localization was right PS in 68 patients, left PS in 19 patients, and coronary sinus and its branches in seven patients. Common to all the patients with posteroseptal AP was a negative delta in at least two inferior leads. The most sensitive and specific parameter for differentiating left posteroseptal APs from right posteroseptal APs was an R/S ratio �1.0 in lead V1 (sensitivity 100 and specificity 100). The R-wave amplitude in lead I (sensitivity 54, specificity 67), and delta ventricularatrial interval (sensitivity 75, specificity 87) had much lesser sensitivity and specificity in this regard. The epicardial posteroseptal APs were discriminated from endocardial variant by the positive delta in aVR (sensitivity 71 and specificity 99) and negative delta in II (sensitivity 100 and specificity 20). Delta wave polarity in V1 was not helpful for differentiating right-sided from left-sided posteroseptal APs. Conclusions: This study demonstrated that in patients with posteroseptal AP, successful ablation site could be predicted to be on the right or left endocardial surface using R/S ratio in lead V1. Necessity for Coronary sinus catheterization and angiography is predictable using delta wave polarities in leads aVR and II. © 2008, The Authors