Electrocardiographic estimation of successful ablation site in patients with manifest inferior paraseptal accessory pathway

• We examined electrocardiographic findings to estimate successful ablation site in patients with single manifest inferior paraseptal accessory pathway (AP).
• Delta wave polarity and R/S ratio in lead V1 differentiate right endocardial inferior paraseptal APs from the left endocardial APs.
• R wave amplitude in lead I is greater in right endocardial inferior paraseptal APs than the left endocardial APs.
• Delta wave polarity and R/S ratio in lead II, delta wave polarity in lead AVR, delta wave polarity and R/S ratio in lead V1 predict epicardial inferior paraseptal APs.

Inferior paraseptal accessory pathways (APs) have a wide distribution and prediction of AP location before radiofrequency ablation is very important in such pathways. We aimed to estimate successful ablation site based on electrocardiogram in 137 patients (mean age: 25.8 ± 9.0; 126 males) with single manifest inferior paraseptal AP.Right endocardial inferior paraseptal APs were discriminated from left endocardial APs with an R/S ratio < 1 (p < 0.001) and negative delta wave in lead V1 (p < 0.001). Epicardial inferior paraseptal APs were differentiated from endocardial APs by a negative delta wave in lead II (p = 0.001), positive delta waves in AVR (p < 0.001) and V1 (p = 0.012), R/S ratio < 1 in lead II (p = 0.03), and R/S ratio ≥ 1 in V1 (p = 0.04).Delta wave polarity and R/S ratio in lead V1 differentiate right endocardial inferior paraseptal APs from left endocardial APs. Delta wave polarities in leads II, AVR and V1, and R/S ratios in leads II and V1 estimate epicardial inferior paraseptal APs.