Earliest activation time is a good predictor of successful ablation of idiopathic outflow tract ventricular arrhythmias

BACKGROUND: In idiopathic outflow tract ventricular arrhythmias (OT‐VAs), identifying the site with the earliest activation time (EAT) using activation mapping is critical to eliminating the arrhythmogenic focus. However, the optimal EAT for predicting successful radiofrequency catheter ablation (RFCA) has not been established. HYPOTHESIS: To evaluate the association between EAT and successful RFCA in idiopathic OT‐VAs and to determine the optimal cut‐off value of EAT for successful ablation. METHODS: We retrospectively analyzed patients undergoing RFCA for idiopathic OT‐VAs at a single center from January 2015 to December 2019. RESULTS: Acute procedural success was achieved in 168 patients (87.0%). Among these patients, 158 patients (81.9%) were classified in the clinical success group according to the recurrence of clinical VAs during median (Q1, Q3) follow‐up (330 days [182, 808]). EAT was significantly earlier in the clinical success group compared with the recurrence (p = .006) and initial failure (p < .0001) groups. The optimal EAT cut‐off value predicting clinical success was −30 ms in the right ventricular outflow tract (RVOT) with 77.4% sensitivity and 96.4% specificity. In all cases of successful ablation in the left ventricular outflow tract (LVOT), EAT in the RVOT was not earlier than −29 ms. CONCLUSIONS: EAT in patients with successful catheter ablation was significantly earlier than that in patients with recurrence and initial failure. EAT earlier than −30 ms could be used as a key predictor of successful catheter ablation as well as an indicator of the need to shift focus from the RVOT to the LVOT.