Simple pacing maneuvers for differentiating right versus left-sided approach in manifest posteroseptal accessory pathway ablation.

BACKGROUND: Accurate localization of posteroseptal (inferior paraseptal) APs during electrophysiological study (EPS) often pose diagnostic challenges due to the complex anatomy of the inferior paraseptal region. AIM: We aimed to study simple pacing maneuvers for differentiating manifest posteroseptal APs, which can be ablated from a right- or left-sided approach. PATIENTS AND METHODS: 65 patients with possible manifest posteroseptal AP were included in a prospective observational study. EPS and ablation were done for all patients. During EPS, we measured the stimulus to atrial (SA) interval during right ventricular (RV) posterobasal septal and apical pacing (basal & apical SA) in sinus rhythm, SA index (basal SA-apical SA interval) and, the number of QRS complexes showing fixed SA interval in the transition zone during RV entrainment of orthodromic atrioventricular tachycardia. RESULTS: 65 patients (48% male) were included with a mean age of 32.8 ± 10 years. SA interval during posterobasal RV pacing can significantly predict the right septal approach at a cut-off ≤113 with 73.1% sensitivity, 77.3% specificity (P < 0.001 and AUC = 0.836). SA index <0 can also predict right septal approach with 87.5% sensitivity and 100% specificity (P < 0.001). Also, the number of QRS with fixed SA in the transition zone predict the right septal approach group, with a cut-off of >2, yielding 100.0% sensitivity and 93.3% specificity (P < 0.001, AUC = 0.990). CONCLUSION: Our study demonstrated that simple and practical pacing maneuvers can effectively predict the optimal ablation approach for manifest posteroseptal accessory pathways with near-perfect diagnostic accuracy. TRIAL REGISTRATION NUMBER (IRB): 04-2023-200550.