Stereotactic arrhythmia radioablation (STAR): safety and efficacy in first 50 patients

Background

Patients suffering implantable cardiac defibrillator (ICD) shocks for Ventricular Tachycardia (VT) despite anti-arrhythmic drugs (AADs) remain at high risk of further shocks and death without ablative therapy.

Purpose

To determine safety and efficacy outcomes in all patients receiving stereotactic arrhythmia radioablation (STAR) in our centre with a minimum of six months follow-up.

Methods

We performed STAR using multimodal imaging and non-invasive mapping to target a single fraction of 25 Gy delivered as an out-patient. Patients referred to the STAR programme were at high-risk of recurrent shocks, had VT recurrence despite prior catheter ablation (CA), or were unable to receive CA (e.g. LV thrombus). All patients were taking anti-arrhythmic drugs (AADs) (amiodarone: 92%, beta blockers: 86%). No patients were declined STAR for any reason, and all were entered into a prospective registry. We describe outcomes in all patients with a minimum of six months follow up. No blanking period was observed.

Results

50 patients underwent STAR and followed for a minimum of six months. Mean age of all patients was 69 years, 84% were male, and the aetiology was Ischaemic Cardiomyopathy (ICM) in 64% (Table 1). All patients suffered VT despite AADs with elevated PAINESD (17 IQR 14-21) and Charlson Index (6 IQR 5-8), predicting patients were at high risk of recurrent VT and death (Table 1).

CTCAE grade ≥2 events were observed in 4 patients (8%) post-STAR. There were two cases of CTCAE grade 3 pneumonitis at 6 months, requiring steroid therapy. There were 2 cases of pericarditis: one CTCAE grade 2 at 6 months, self-resolving, and one CTCAE 3 at 22 months, requiring elective pericardiocentesis. No clinically significant deleterious effects on LV ejection fraction, valve function or ICD performance were observed.

Following STAR therapy, ATP events decreased from 54 to 15 per-patient-year (95% CI 0.259–0.298; p<0.001) and shocks decreased from 8 to 2 per-patient-year (95% CI 0.152–0.232; p<0.001) at up to 6 years follow up. Of all 50 patients, 40% (n=20) died during follow up after a median of 10 months (IQR 5-14). 70% (n=14) of those who died were free from VT, with 75% (n=15) dying of non-cardiovascular causes.

Of 35 patients who completed 12-month follow-up, 68% (n=24) were free from shock and death. We compared the number of VT events pre and post STAR (12 months). 27 patients (77%) saw a reduction in ATP events with a median burden reduction of 100% (IQR 91-100%). Furthermore, 30 patients (86%) saw a reduction in shocks at 12-months, with a median burden reduction of 100% (IQR 80-100%).

Conclusion

STAR appears to be safe and effective for patients with VT at high risk of recurrent shocks or death at up to 6 years of follow up. Randomised multicentre studies of RA are needed to confirm these results.STAR ESC Table 1