Assessing the Ability of Substrate Mapping Techniques to Identify Scar-related Arrhythmia Circuits Through Computational Modelling

Fernando Campos1, Michele Orini2, Robert Arnold3, John Whitaker4, Mark O'Neill4, Reza Razavi4, Gernot Plank3, Ben Hanson5, Pier Lambiase5, Bradley Porter4, Christopher Aldo Rinaldi4, Jaswinder Singh Gill6, Peter Taggart5, Martin Bishop4
1School of Biomedical Engineering and Imaging Sciences, King's College London, 2University College London, Department of Mechanical Engineering, 3Medical University of Graz, 4King's College London, 5University College London, 6Guy's and St Thomas' NHS


Background: accurate identification of targets for catheter ablation therapy of ventricular tachycardias (VTs) in the infarcted heart remains a significant challenge. Identification of such targets often requires VT-induction to delineate the reentrant circuit. If induction is not possible, substrate ablation strategies can still be performed. However, VT recurrence after the procedure remains common.

Objective: to use computer simulations to compare the ability of different electroanatomical maps to identify the VT exit site during pacing.

Methods: an MRI-based computational model of the porcine post-infarction heart was constructed to simulate VT and paced rhythm. Electroanatomical maps were constructed based on endocardial electrogram features and the reentry vulnerability index (RVI - a metric combining activation, AT, and repolarization timings to identify tissue susceptibility to reentry). Potential ablation targets were compared for highest or lowest 5% values. The minimum distance, d, between the VT exit site and the targets was measured.

Results: the RVI performed better than the other metrics at detecting the VT exit site. The minimum distance between sites of lowest RVI and the exit site was 3.2mm compared to 13.1mm and 15.9mm in AT and voltage maps. Since scar transmurality was not homogeneous, parameters derived from all signals (including dense scar regions) were used to construct the maps, improving the performance of the RVI significantly.

Conclusions: among all metrics, the RVI identified the vulnerable region closest to VT exit site suggesting that activation-repolarization metrics may improve the detection of pro-arrhythmic regions without inducing VT even in infarcts with non-transmural scars.