Background: The course of the AV nodal slow pathway in patients with persistent left superior vena cava (PLSVC) has not been fully elucidated, and its optimal ablation site remains controversial. The present study investigated the electrophysiological characteristics of AV nodal reentrant tachycardias (AVNRTs) associated with PLSVC and the safety and efficacy of their radiofrequency catheter ablation (RFCA). Methods and results: Eight consecutive patients with PLSVC (7 women and 1 man; mean age, 36.3 +/- 6.0 years) out of 325 with AVNRT who underwent RFCA at our center between June 2012 and June 2015 were included. After electrophysiological study, ablation was successfully completed at the routine target site in 2 patients, while the other 6 required ablation at the anterior wall of the coronary sinus within 1 cm from the ostium, where effective target potential was a relatively fractionated atrial electrogram followed by a large ventricular electrogram (A/V ratio > 1: 3) and impedance was approximately 20 O higher than at the routine target site. Conclusions: RFCA is feasible and safe for AV nodal modification associated with PLSVC, with the majority of target sites located in the anterior wall of the coronary sinus within 1 cm from the ostium.