Staff EP University of Ottawa Heart Institute Ottawa, Ontario, Canada
Background: Ventricular arrhythmias are the leading cause of sudden cardiac death, accounting for the majority of 60,000 cardiac arrests annually in Canada. Stereotactic arrhythmia radiotherapy (STAR) is an emerging and completely non-invasive treatment option for ventricular arrhythmia ablation. While early clinical results are promising, treatment planning remains a barrier, resulting in procedural delays and high interobserver variability.
METHODS AND RESULTS:
Objective: To evaluate the accuracy, precision, and duration of STAR targeting using SHARP-VT, a dedicated multi-modality imaging software tool developed to assist STAR target planning.
Methods: Five electrophysiologists (EPs) without prior STAR experience independently performed retrospective targeting on 10 patients (6 ICM, 4 NICM, VT-free 1-year post-STAR). Imaging consisted of contrast-enhanced CT, perfusion and viability PET, and electrocardiographic imaging (ECGi), all co-registered in SHARP-VT. One case was randomly repeated to assess intra-operator variability. Total planning time was measured from case-loading to target RT-DICOM export. Accuracy was assessed by comparing user-generated targets to clinical treatment targets. Inter- and intra-user variability were evaluated using Dice Similarity Coefficient (DSC) and average Hausdorff Distance (HD). NASA-TLX surveys were completed at study end to assess perceived task load in six categories (mental, physical, and temporal demand, performance, effort, and frustration).
Results: Average case planning time was 11 min ± 7 min. Task load was reduced compared to reported values for baseline planning methods in all six categories (p < 0.05). Novice users’ target volumes tended to be smaller than the clinical standard volumes (58 ± 30 cc vs 73 ± 30 cc, p=0.11). The average intra-user HD was 4 ± 2mm with DSC of 0.72 ± 0.13, whereas inter-user HD was much higher at 14 ± 9 mm, with lower DSC of 0.41 ± 0.16.
Conclusion: SHARP-VT was considered easy to use and facilitated rapid target acquisition by electrophysiologists without STAR experience. Novice users tended to select smaller treatment volumes with inter-user variability using SHARP-VT comparable to prior reports from expert users without a dedicated tool. SHARP-VT may streamline STAR treatment planning and training, improve accessibility, and offer accuracy comparable to current methods. Prospective evaluation with EPs experienced in STAR is required to validate its role in routine clinical practice.
