Target delineation workflow and outcomes of stereotactic cardiac radioablation

Stereotactic body radiation therapy (SBRT) is an emerging modality for the treatment of ventricular tachycardia (VT). The workflow for delineation of the SBRT target is evolving.

This project describes the procedural workflow and outcomes of SBRT for VT.

The primary indication for SBRT was recurrent VT despite maximal contemporary treatment. Target delineation for SBRT involved combining imaging and electrophysiological data. VT burden, defined as the number of sustained VT episodes per month, was compared as the primary outcome. Secondary outcomes assessed included reduction of antitachycardia pacing and defibrillator shock episodes and reduction in the number of antiarrhythmic drugs per patient during follow-up.

Workup for VT target delineation and radiation delivery was conducted in 25 patients receiving 27 SBRT procedures. VT management prior to SBRT consideration included ≥2 catheter ablations in 22 (88%) and surgical sympathectomy in 7 patients (28%). Of the 27 performed cases, SBRT target delineation incorporated electrocardiogram of clinical VT in 16 (59%), at least 2 noninvasive imaging modalities to assess scar in 24 (89%), and invasive electroanatomic mapping in 25 (93%). Among 16 patients with a complete 6-month follow-up, the reduction of VT burden per month was 81% (P < .05). Reduction in antitachycardia pacing and defibrillator shocks per month was 86% and 98%, respectively (P < .05). The number of patients on ≥2 antiarrhythmic drugs decreased from 69% to 0% (P < .01). One patient developed diaphragmatic paralysis after SBRT.

In patients with recurrent VT despite maximal contemporary antiarrhythmic therapies, SBRT offers a safe alternative once the target is adequately delineated by combining imaging and electrophysiological data.