Three-dimensional characterization of ventricular arrhythmias in structural heart disease with a novel digital twin framework

Abstract Background Catheter ablation is a cornerstone treatment for scar-related ventricular arrhythmias arising in patients affected by structural heart disease. Catheter mapping, even when high-density, only allows two-dimensional circuit characterization, while 3D delineation of reentry mechanisms, including the mid-myocardial activation, may allow better target definition and treatment. Purpose To evaluate a novel digital twin framework for ventricular tachycardia (VT) induction and 3D circuit characterization based on late gadolinium cardiac magnetic resonance (LGE-CMR) imaging. Methods Fourteen consecutive patients prospectively enrolled in the ongoing VOYAGE clinical trial for cardiac magnetic resonance (CMR) aided/guided VT ablation at our referral center were retrospectively analyzed. Multidetector computed tomography (MDCT), and LGE-CMR were acquired before procedure. LGE-CMR was segmented with ADAS3D for scar characterization. LGE-CMR derived normalized-pixel-intensity maps were processed with a novel in-house software for VT induction using a standardized protocol (S1 600 ms x 6, S2 350 ms, S3 300 ms, S4 280 ms) pacing from all 17 segments of the left ventricle (LV) to obtain 3D local activation time (LAT) maps, including endocardial, mid-myocardial and epicardial activation. LV was conventionally divided in concentric layers from 10% (endocardial) to 90% (epicardial) of wall thickness. VTs were defined as 3D when circuit involved more than one layer. Activation maps were then imported into CARTO3 suite for compatibility testing purposes. Results A total of 72 sustained VTs were induced in 11 patients (an average of 6,5 VTs per-patient). Four patients were non-inducible. Mean, minimum and maximum cycle lengths were 387±51 ms, 310 ms and 657 ms, respectively. Sixty-one VTs (84,7%) were two-dimensional, since the entire circuit could be observed in a single myocardial layer, while 11 VTs (15,3%) were defined as three-dimensional. 3D activation maps were successfully imported into CARTO3 electroanatomical mapping suite in all cases with full compatibility. Conclusion Our newly developed framework for LGE-CMR-derived VT activation map generation successfully delineated both two-dimensional and three-dimensional reentry circuits, also allowing elucidation of mid-myocardial reentry mechanisms. Further validation and development are required to explore future clinical practice implications.