Sequential Electro-Anatomical Mapping Methodology and Preliminary Results for Reentry Vulnerability Index Estimation

Abstract

Ventricular tachycardia (VT) recurrence after catheter ablation remains frequent and improved ablation strategies are needed. The re-entry vulnerability index (RVI) is an activation-repolarization marker to localize critical sites for VT initiation. Its use is limited since current electro-anatomical mapping systems (EAMS) cannot provide global measurement of activation and repolarization times within a single beat. We carried out a simulation study to assess a simple method to measure RVI using data collected by sequential EAMS and we investigated the effect of background noise, RT variability (σ RT) and ectopics on RVI estimation. The mean correlation coefficient between single ECG beats and a representative template is used as inclusion/exclusion criterion. Localization of the vulnerable region associated with 5% bottom RVI was accurate (sensitivity80±8%, specificity> 99±1%) for moderate to large repolarization variability (5 ≤ σ RT ≤ 20 ms) and moderate level of noise (SN R ≥ 10 dB) but it deteriorated for σ RT ≥ 25 ms and SN R ≤ 5 dB. Sensitivity remained high even when RVI estimates were only moderately accurate (cc > 0.67 ± 0.05, M AE < 25 ± 1 ms). The number of ectopic beats did not affect the results. In the in-vivo case analyzed, the sites of low RVI and VT exit was close (5.1 mm).