185 - Repeat Catheter Ablation vs. Stereotactic Arrhythmia Radioablation for Recurrent Ventricular Tachycardia in Structural Heart Disease: The STAR-VT-2020 Randomized Trial

Purpose/Objective(s): Stereotactic arrhythmia radioablation (STAR) has been proposed as a treatment option for refractory ventricular tachycardia (VT) in patients with structural heart disease (SHD). Because STAR techniques vary from highly focused target irradiation to broader substrate homogenization, clinical outcomes may depend on the treatment concept used. The STAR-VT-2020 randomized trial (NCT04612140) compared a highly focused STAR approach versus repeat catheter ablation (CA) in patients with VT recurrence after a previous CA.

Materials/Methods: Patients with SHD, recurrent symptomatic VT, ICD, and =1 prior VT ablation were randomized 1:1 at two centers using a covariate-adaptive algorithm. Recurrence had to require further intervention, match the previously characterized arrhythmogenic substrate (without repeat mapping/ablation), occur on stable antiarrhythmic therapy, and have reversible causes excluded. In the STAR arm, a predefined focal substrate was irradiated (single fraction, 25 Gy) rather than broad substrate homogenization. In the CA arm, repeat ablation was performed per institutional practice. The primary efficacy endpoint was the first VT recurrence (sustained VT or ICD-treated VT). Secondary endpoints included all-cause mortality. Safety assessments included radiation-specific adverse events and a change in LVEF over 12 months.

Results: In the STAR group, 8/11 patients (73%) required at least one additional catheter ablation (CA) for VT recurrence; of these, 1 patient also underwent repeat STAR. In 6 of the 8 patients requiring repeat CA, the procedure was performed shortly (77±37 days) after the STAR. In the CA group, 4/11 patients (36%) underwent at least one subsequent ablation procedure for VT recurrence; of these, 2 patients also received STAR. Only 2 patients in the CA group underwent repeated ablation within or shortly after the end of the blanking period (10 and 109 days after the study procedure). A total of 6 patients (55%) in the STAR group and 7 patients (64%) in the CA group died. There was no significant change in LV systolic function within 12 months following the trial ablation. LVEF improved by 3.7 ± 6.3% (P = 0.12) after STAR and by 2.4 ± 5.3% (P = 0.27) after CA, with no significant between-group difference (P = 0.68). Among 3 patients who received irradiation to the basal inferolateral segments (AHA model segments #4 or #5), 1 patient with stable grade 2 mitral regurgitation during the first year of follow-up later showed significant progression.

Conclusion: Repeat CA appeared to provide greater clinical benefit than highly focused STAR. However, inclusion of patients with electrical storm may have attenuated apparent STAR efficacy. Importantly, the highly focused STAR approach appeared feasible, with a low risk of radiation-related adverse events and no signal of excess mortality.