Abstract Background Stereotactic arrhythmia radioablation (STAR) is a promising non-invasive therapy for patients with ventricular tachycardia (VT). Accurate identification of the arrhythmogenic volume, or clinical target volume (CTV), on the radiotherapy 4D planning computed tomography (CT) scan is key for STAR efficacy and safety. This case report illustrates our workflow of electro-structural image integration for CTV delineation. Case summary A 72-year-old man with ischemic cardiomyopathy and VT storm, despite two (endocardial and epicardial) catheter-based ablations, was consented for STAR. A 3D electro-structural arrhythmia model was generated from co-registered electroanatomic voltage and activation maps, ECG-imaging and the cardiac CT angiography scan (in ADAS 3D), pinpointing the VT isthmus and inferoapical VT exit. At this location, an area with short recovery times was found with ECG-imaging. A multidisciplinary team delineated the CTV on the transmural ventricular myocardium, which was fused with the 4D planning CT scan using a DICOM RT file. The CTV was 63% smaller compared to using the conventional 17-AHA segmental approach (11 vs 24 cm3). A single fraction of 25 Gy was delivered to the internal target volume. After an 8-week blanking period, no VT recurrences or radiation-related side-effects were noted. Eight months later, the patient died from end-stage heart failure. Discussion We report a novel workflow for 3D-targeted and ECG-imaging aided CTV delineation for STAR, resulting in a smaller irradiated volume compared to segmental approaches. Acute and intermediate outcome and safety were favourable. Non-invasive ECG-imaging at baseline and during induced VT holds promise for STAR guidance.