One-year outcomes after stereotactic body radiotherapy for refractory ventricular tachycardia

BACKGROUND Cardiac stereotactic body radiotherapy (SBRT) has emerged as a promising noninvasive treatment for refrac-tory ventricular tachycardia (VT). OBJECTIVE The purpose of this study was to describe the safety and effectiveness of SBRT for VT in refractory to extensive ablation. METHODS After maximal medical and ablation therapy, patients were enrolled in a prospective registry. Available electrophys-iological and imaging data were integrated to generate a plan target volume. All SBRTs were planned with a single 25 Gy fraction using respiratory motion mitigation strategies. Clinical outcomes at 6 weeks, 6 months, and 12 months were analyzed and compared with the 6 months prior to treatment. VT burden (implantable cardioverter-defibrillator [ICD] shocks and antitachycardia pacing sequences) as well as clinical and safety outcomes were the main outcomes. RESULTS Fifteen patients were enrolled and underwent planning. Fourteen (93%) underwent treatment, with 12 (80%) surviving to the end of the 6-week period and 10 (67%) surviving to 12 months. From 6 week to 12 months, there was recurrence of VT, which resulted in either appropriate antitachycardia pacing or ICD shocks in 33% (4 of 12). There were significant reductions in treated VT at 6 weeks to 6 months (98%) and at 12 months (99%) compared to the 6 months before treatment. There was a nonsignificant trend toward lower amiodarone dose at 12 months. Four deaths occurred after treatment, with no changes in ventricular function. CONCLUSION For a select group of high-risk patients with VT refractory to standard therapy, SBRT is associated with a reduction in VT and appropriate ICD therapies over 1 year.