Stereotactic Body Radiation Therapy for VT in Chagas Cardiomyopathy: A Prospective Phase I/II Pilot Study.

BACKGROUND

Stereotactic body radiation therapy (SBRT) is a novel noninvasive therapy for ventricular tachycardia (VT), but its role in Chagas cardiomyopathy remains unexplored.

OBJECTIVES

This study aimed to evaluate the safety and preliminary efficacy of SBRT for refractory VT in patients with chronic Chagas cardiomyopathy.

METHODS

We prospectively enrolled patients with Chagas cardiomyopathy and refractory VT who had failed or were ineligible for catheter ablation. A single 25-Gy fraction of SBRT was delivered to an arrhythmogenic substrate identified by multimodality imaging. The primary outcomes were a reduction in VT burden and treatment-related adverse events.

RESULTS

Eleven patients (age: 64.9 ± 6.7 years; LVEF: 31.6 ± 9.8%) with implantable cardioverter-defibrillators, 9 of whom had prior failed ablations, underwent SBRT. The median internal target volume was 27.3 cm3, and the planning target volume was 91.1 cm3. During a median follow-up of 160 days, VT recurred in 10 patients. The median time to recurrence after a 6-week blanking period was 79 days (IQR: 51.5-167). The patient without recurrence died of noncardiac causes 22 days after SBRT. Comparing the 12 months after SBRT with the 6 months before SBRT, there was a statistically significant reduction in the burden of VT episodes (P = 0.040), antitachycardia pacing therapies (P = 0.012), and combined antitachycardia pacing/shocks (P = 0.022), although isolated implantable cardioverter-defibrillator shocks were not statistically significantly reduced. The 12-month overall survival was 45.5%, and no severe treatment-related adverse events were reported.

CONCLUSIONS

SBRT is a feasible approach for refractory VT in Chagas cardiomyopathy. Despite a high rate of VT recurrence, SBRT statistically significantly reduced the burden of ventricular arrhythmia, warranting further investigation.