Middle-term safety and efficacy after stereotactic arrhythmia radiotherapy: results from the prospective STARNL registry

Background Stereotactic Arrhythmia Radiotherapy (STAR) is a promising treatment option for patients with therapy-refractory ventricular tachycardia (VT). Despite encouraging safety and efficacy results in short-term follow-up studies, the middle- and long-term safety and efficacy remain unclear. Objective To evaluate the safety and efficacy of STAR for VT over a middle-term follow-up period of two years. Methods The STARNL registry is a prospective registry including patients treated with STAR for therapy-refractory VT within a prospective trial or based on compassionate use. Patients with VT episodes despite optimal conventional antiarrhythmic therapy were considered therapy-refractory and were treated with a single fraction of 25 Gy stereotactic body radiotherapy. Safety and efficacy were evaluated over a middle-term follow-up period of two years and included the evaluation of severe or worse (CTCAE grade ≥3) adverse events (AEs) and the evaluation of treated VT episodes (excluding a 6-week blanking period), respectively. Results Seven patients were included in this study (all male, age 54-83). All had ischemic cardiomyopathy (left ventricular ejection fraction 17-52%) and the median number of VT ablations before STAR was 1 (0-5). In the 12 months before STAR, a median of 41 (range 8-138) treated VT episodes were observed. During follow-up, two patients died of non-treatment-related, non-cardiac causes (7 and 11 months; cross in Figure 1). Three severe possibly, probably or definitely treatment-related AEs were observed, all in one patient (chest-wall pain, bronchopulmonary hemorrhage and cardiac chest-pain at 4, 21 and 22 months after treatment, respectively). Efficacy results after STAR are shown in Figure 1. Three patients underwent one (P4 and P5) or two (P7) VT ablation(s) after STAR (bullseye in Figure 1). Conclusion In this middle-term follow-up study, severe treatment-related AEs were scarce and manageable. Although VT recurrences were common in some patients, new VT ablations were feasible in these previously therapy-refractory patients.