Image Integration to Identify Histologic and Electroanatomic Ventricular Scar: A Clinicopathological Study Comparing...

Cardiac magnetic resonance (CMR) image integration technologies offer promise to guide delineation of ventricular scar and arrhythmogenic substrate; however, there are limited co-registered histological data or comparative studies of commonly used CMR segmentation tools for ventricular tachycardia (VT) ablation.

This study sought to validate 2 commonly used vendor systems (ADAS-3D and inHEART) to integrate CMR late gadolinium enhancement to electroanatomic mapping in catheter ablation of VT.

Five sheep underwent anteroseptal infarction with electroanatomic mapping (129 ± 12 days postinfarct). A whole heart histological model of the postinfarction scar was created. CMR was segmented by ADAS-3D and inHEART and validated with histology for 3 layers (the endocardium, intramural layer, and epicardium). A subsequent clinical validation study was performed with 5 human subjects (1 postinfarction VT, 4 nonischemic cardiomyopathy). Critical sites of VT and functional substrate (deceleration zones) were matched to ADAS-3D and inHEART scar.

CMR-based ADAS-3D and inHEART have comparable accuracy (>75%) with moderate agreement to identify endocardial and intramural scar compared to gold standard whole-heart histology but poorer performance (modest accuracy [60%-68%] and fair agreement in the epicardial layers). Both technologies performed poorly to identify noncompact scar. Critical sites of VT colocalize reliably with ADAS-3D and inHEART scar (88% falling within 1 scar layer). More than 80% of VT critical sites demonstrated CMR late gadolinium enhancement scar in more than 1 layer.

ADAS-3D and inHEART image integration provide similar characterization of scar distribution and allowed similar display of the anatomic relation of critical re-entry circuit sites detected by mapping to scar. However, limitations exist in the performance of these technologies to identify epicardial and noncompact scar.