Stereotactic arrhythmia radioablation in refractory ventricular tachycardia: a systematic review and meta-analysis of efficacy and survival outcomes

Recently, stereotactic arrhythmia radioablation (STAR) has emerged as a novel, non-invasive alternative treatment option for patients presenting with refractory ventricular tachycardia (VT). Early studies suggest promising reductions in VT burden following STAR, yet comprehensive evaluations of its efficacy and safety remain limited.

To assess the efficacy and survival outcomes of STAR in patients with refractory VT in a systematic review.

This systematic review adheres to the PRISMA and MOOSE guidelines. The literature search was performed in MEDLINE and EMBASE databases from inception to June 30, 2024 including prospective and retrospective studies on STAR for monomorphic VT. The search, data extraction and quality assessment was performed by 2 independent investigators (EG, EVK) with a third investigator adjudicating in case of disagreement (BV). Quality assessment was performed using the Risk Of Bias In Non-randomized Studies of Interventions (ROBINS-I) tool. The following outcomes were extracted and recalculated: (1) number of patients free of VT at the end of follow-up, excluding the blanking window if applied, (2) percentage reduction in VT episodes/month, (3) percentage reduction in ICD shocks/month, and (4) survival status at end of follow-up. Descriptive data is presented as weighted means. Meta-analysis of proportions was performed using the "Metaprop" package in STATA using a random effects model with double arcsine transformation to adjust for data asymmetry.

A total of 205 patients with a mean follow-up of 11.5±5.5 months were included from 12 prospective and 10 retrospective studies (age 65.8±4.6 years, 85.8% male, left ventricular ejection fraction 29.8±5.0, 54.3% ischemic cardiomyopathy). Among the included studies, 4 were assessed as having a low risk of bias (n=38), and 18 had a moderate risk of bias (n=167); none were assessed as having a serious or critical risk of bias according to the ROBINS-I tool.

The overall survival at the end of follow-up was 74.6% (Figure 1; n=205; 95% Confidence Interval (CI) 67.1%-81.7%; I²=15.3%; p=0.256). The percentage reduction in VT episodes/month was 77.1% (n=89; 95% CI 57.5%-92.8%; I²=65.0%; p<0.001) while this was 81.8% for reduction in ICD shocks/month (n=110; 95% CI 61.7%-96.6%; I²=77.5%; p<0.001). Only 25% of patients were free of VT at end of follow up (Figure 2; n=133; 95% CI 11.8%-40.4%; I²=65.0%; p<0.001). These results were consistent in a sensitivity analysis comparing prospective and retrospective studies.

STAR is associated with a promising efficacy demonstrated by the significant reduction in VT episodes/month and ICD shocks/month. However, only a small proportion of patients was free of ventricular tachycardia at end of follow up. This analysis is limited by the variability in reporting, including the use of a blanking period, indicating the need for standardized reporting.Figure 1:

Survival.