From Scar to Stereotactic Arrhythmia Radioablation With inHEART-Guided Targeting: A Comprehensive Evaluation of Stereotactic Ablation for Ventricular Tachycardia in a Single-Center Experience.

Abstract

This study aimed to present the clinical workflow developed for stereotactic arrhythmia radioablation, with a particular focus on the inHEART multimodality platform used for cardiac imaging integration and 3-dimensional substrate segmentation. We also report the clinical outcomes and dosimetric results of the initial 18 patients treated. All patients underwent contrast-enhanced cardiac computed tomography, including late-enhancement imaging and optional cardiac magnetic resonance imaging. Imaging data were processed using the inHEART multimodality platform for specific imaging in cardiology (MUSIC), which enabled automatic 3-dimensional segmentation of cardiac anatomy, identification of the scar substrate, and integration of electrophysiological data to define the clinical target volume. The stereotactic body radiation therapy inHEART module exported target structures in digital imaging and communications in medicine-radiation therapy format to the Eclipse Treatment Planning System. Three-dimensional computed tomography simulation scans were acquired to account for cardiorespiratory motion, and an internal target volume/planning target volume (PTV) was derived accordingly on expiratory phases. Treatment was delivered with volumetric modulated arc therapy in a single fraction of 25 Gy to the PTV using a TrueBeam STx linac. Clinical effectiveness was assessed through ventricular tachycardia (VT) burden and implantable cardioverter defibrillators shock reduction. Median clinical target volume, internal target volume, and PTV volume were 14.50 cc (range, 4.32-32.6 cc), 22.13 cc (range, 5.15-49.15 cc), and 58.42 cc (range, 20.87-109.76 cc), respectively. Excellent dose coverage was achieved, median PTV D99% was 25.25 Gy (range, 21.94-27.51 Gy), with a mean Paddick conformity index of 0.89 ± 0.08. All organs at risk met the dose constraints. At 12 months, 78% of patients showed >75% VT reduction, and 94% of surviving patients experienced a limited number of shocks (<2). Integrating the inHEART stereotactic body radiation therapy module within a standardized multimodal imaging workflow enables accurate stereotactic arrhythmia radioablation planning and delivery. This approach proved feasible, robust, and safe for managing refractory VT.