Benefits of stereotactic arrhythmia radioablation (STAR) for ventricular tachycardia at one year similar in ischemic and non-ischemic patients

Background

Patients with non-ischemic cardiomyopathy (NICM) undergoing catheter ablation (CA) for Ventricular Tachycardia (VT) have less favourable outcomes compared to patients with ischemic cardiomyopathy (ICM).

Purpose

To compare outcomes between patients with ICM versus NICM 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. All patients referred for STAR were taking anti-arrhythmic drugs (AADs) (amiodarone: 92%, beta blockers: 86%) with implantable cardiac defibrillator (ICD) in situ and remained at high-risk of recurrent shocks and death (see Table). 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. Mann-Whitney U and Student’s t-tests were applied for continuous variables and chi-squared was used for categorical variables, significance set at p<0.05.

Results

50 patients underwent STAR and were followed for 6 to 72 months. Mean age of all patients was 69 years, 84% were male, and the aetiology was Ischaemic Cardiomyopathy (ICM) in 32 patients (64%). Patients with ICM were older, had more comorbidities, and a higher risk of VT recurrence (Table 1).

12 patients with ICM (38%) died during follow-up after a median of 12 (IQR 8-17) months following STAR, 8 (67%) patients who died were free of VT and 83% (n=10) died of non-cardiovascular causes. 8 patients with NICM (44%) died during follow-up after a median of 6.5 months (IQR 4-8), with 75% (n=6) patients free of VT and 75% (n=6) died due to non-cardiovascular causes.

Of the 28 surviving patients at 12-months (54%), we compared the frequency of VT events pre and post STAR across the two groups. The shock-free survival rate for patients with ICM was 56% (n=10), vs. 80% (n=8) in NICM. At one year, ICM patients had a 53% reduction in ATP events vs. 21% in NICM (95% CI 1.43-1.94; p<0.001). ICM patients had a 61% shock reduction vs. 93% in the NICM group (95% CI 0.08-0.37; p<0.001).

CTCAE grade ≥2 events were observed in 4 patients (8%) post-STAR. No clinically significant deleterious effects on LV ejection fraction, valve function or ICD performance were observed.

Conclusion

In this small, single-centre study, STAR appears similarly effective at VT suppression in both ICM and NICM patients at up to 6 years of follow-up. Randomised multicentre studies of STAR are needed to confirm these results.STAR ICMvNICM Table1