Utility of automated matching technique for interpretation of pace mapping in patients ablated due to outflow tract ventricular arrhythmias

Purpose: There are two techniques for localization of the origin of the ventricular outflow tract arrhythmias during transcatheter ablation (TA): activation and pace mapping (PM). One of the disadvantages of classic PM is the operator's subjective interpretation. The aim of this single center retrospective study was to evaluate the value of automated matching technique (AMT) in patients ablated due to outflow tract ventricular arrhythmias (OTA). Methods: From overall group of 105 patients with OTA who were scheduled for TA, AMT (BARD LabSystem Pro) was accessible in 42 patients (21 RVOT, 21 LVOT, 28 women, aged 51,5+/_ 12,7 years). We used AMT to compare spontaneous arrhythmia ORS (spontQRS) with paced QRS complexes during pace mapping (PM) in sites where RF application was successful and in sites where RF applications were unsuccessful. The concordance was presented in percents for every single lead and for all 12-leads as average matching scores (AMS). Results: AMS of PM at sites of successful ablation varied from 74 to 99% (mean 94,6±5,4) and from 47 to 90% (mean 80.2±12.6) at sites of unsuccessful ablation. PM in unsuccessful RF sites was significantly less similar to spontQRS morphologies than in successful RF sites (p=0.0001). AMS that indicate optimal ablation site was 88,5% for RVOT arrhythmias (sensitivity and specificity=100%) and 89% for LVOT arrhythmias (sensitivity=90%, specificity=60%). Highest template matches (small differences) were met at the leads: II,III,aVF,aVR for successful and unsuccessful ablation sites. In sites of successful ablation lowest template matches (differences between spontQRS and paced ORS) were present in leads I,aVL,V3,V4 in RVOT and in leads I,aVL,V1-V3 in LVOT. Conclusions: This analysis revealed that AMT is valuable technique for identification of sites of successful ablation in OTA. The concordance of spontQRS morphology with paced QRS morphology at sites of successful ablation was significantly higher than at sites of unsuccessful ablation. AMT showed that ECG leads I,aVL,V1-V4 play the crucial role in identification of the site of successful ablation in patients with OTA.