Noninvasive Cardiac Radioablation for Ventricular Tachycardia: Results of the STARNL-1 Trial

Abstract

<h3>Purpose/Objective(s)</h3> Radioablation or stereotactic arrhythmia radiotherapy is a promising new last-resort treatment modality for patients with recurrent ventricular tachycardia (VT) who are considered therapy refractory. Experience with radioablation is steadily growing worldwide as result of promising efficacy and safety results. Prospective trials are needed to confirm these results. The STARNL-1 study was designed to prospectively evaluate the efficacy and safety of cardiac radioablation in patients with therapy-refractory ventricular tachycardia. <h3>Materials/Methods</h3> The prospective STARNL-1 trial is a single-arm, pre-post, intervention study. In 6 patients, the pro-arrhythmic cardiac region was identified and treated with a single stereotactic radiotherapy fraction of 25 Gy. Patients who were considered therapy-refractory, with recurrences after (multiple) VT ablations and high doses of class 1-3 anti-arrhythmic drugs, were included. For this analysis, the number of treated VT-episodes 6-months before and after treatment, excluding events in the 6-week blanking period, were compared. Safety analysis included evaluation of (serious) adverse events, echocardiography and lung function tests. <h3>Results</h3> All six patients (6/6, 100%) included in the STARNL-1 trail completed the 6-month follow-up. All patients were male (age range 55-83 years) and had an ischemic cardiomyopathy (median ejection fraction: 38% [range 24-52]. The median planning target volume was 187ml (range 93-372.2) and radiation beam-on times were all below 7 minutes. There were no significant alterations in hs-Troponin-T as a marker for myocardial injury comparing baseline (2-3h before treatment) to 3h (+9.7% [-2.3;31.1], p=0.34), 12h (+13.3 [-2.1;17.8], p=0.22) and 24h (+8.0% [9.8;53.3], p=0.40) post-treatment. The median number of treated VT episodes significantly reduced from 24 (range: 6-107) in the 6 months before treatment to 3 (range 0-15) after treatment, p=0.028. The median reduction percentage was 88.0% (range 85-100%). No serious treatment related adverse events occurred during follow-up. Comparing 3 months after treatment with baseline, the median change in ejection fraction was +12% (range: -27 to +33) and the median reduction in 1 second forced expiratory volume (FEV1) and diffusion capacity (DLCO) were both below <15%. <h3>Conclusion</h3> The results of the prospective STARNL-1 evaluating cardiac radioablation for therapy-refractory VT patients are very promising with regards to efficacy and safety.