3256Long-term safety of stereotactic body radiotherapy for ablation of ventricular tachycardia: a multicentric study

Abstract

Abstract Background Contemporary stereotactic body radiotherapy (SBRT) enables to accurately concentrate high radiation doses to small volumes of myocardial tissue. There is a rising interest in using SBRT to modify arrhythmogenic substrate in patients with previously failed radiofrequency catheter ablation. However, data on the safety of SBRT for the treatment of VT are lacking. Purpose This study evaluated the long-term safety of SBRT for the treatment of VT. Methods SBRT was performed in patients with structural heart disease and failed catheter ablation for VT. The critical part of the VT substrate was identified by electroanatomic mapping (EAM) using a combination of voltage mapping, pace mapping, and activation mapping; and it was marked on a contrast-enhanced computer tomography study as a target for radioablation. SBRT was performed using a radiosurgery system with real-time motion tracking using the tip of the electrode of an indwelling defibrillator as a fiducial marker. A total radiation dose of 25 Gy was delivered to the ablation target in a single session during free breathing. Radiation-induced toxicity was evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Results Between 2014 and 2018, 18 patients from two electrophysiology centres underwent SBRT for recurrent, drug-resistant VT after previously failed catheter ablation (17 male, 1 female; mean age 63±9 years; 14 ischemic cardiopathy, 3 dilated cardiopathy, 1 fibroma). The mean volume of the ablation target was 34±17 ml, and the mean duration of the therapy was 78±14 minutes. No patient exhibited acute (up to 3 months) elevation of troponin, pericardial effusion, or a decrease in left ventricular ejection fraction from baseline. Four patients developed acute mild nausea, which waned after antiemetic drugs. Two patients gradually developed significant progression of mitral regurgitation after SBRT. One of the patients was treated medically (grade 3 toxicity), but the other had to undergo mitral valve replacement (grade 4 toxicity). No other cardiac or pulmonary radiation related toxicity was observed during a median follow-up of 23 months. Three patients died at 54, 43, and 18 month after SBRT. None of the deaths was related to VT recurrence or complication of SBRT. CARTO, Radiation dose and Survival Conclusions This is the largest series of patients who underwent EAM-guided SBRT for VT as a bailout therapy after previously failed radiofrequency catheter ablation. Our preliminary data indicate the feasibility and safety of the procedure. To further investigate long-term safety and efficacy of SBRT for VT, we initiated a prospective multicentric study (NCT03819504). Acknowledgement/Funding Supported by RVO-FNOs/2014