Stereotactic arrhythmia radioablation in patients with refractory ventricular tachycardia: a systematic review and meta-analysis

Stereotactic arrhythmia radioablation (STAR) is a novel, non-invasive treatment for therapy-refractory ventricular tachycardia (VT). In STAR, a high dose of radiation is used to non-invasively target and treat the VT substrate. Initial studies indicate promising VT burden reduction, but comprehensive efficacy and safety evaluations remain limited. A systematic review (Preferred Reporting Items for Systematic Reviews and Meta-Analyses/Meta-analysis Of Observational Studies in Epidemiology guidelines) included studies on STAR for monomorphic VT identified up to 30 June 2024 via MEDLINE and EMBASE. Outcomes assessed were freedom of VT, percentage reduction in VT episodes and implantable cardioverter-defibrillator (ICD) shocks per month, survival and adverse events (AEs). Meta-analyses included prospective and retrospective studies only, using random-effects models with double arcsine transformation. Subgroup analyses by study design and planning target volume (PTV) were performed. AEs were qualitatively analysed and classified by organ system, severity and causality. The meta-analysis included 215 patients from 22 studies (age 66.0±4.4 years, 85.9% men, left ventricular ejection fraction 29.8±5.0%, 52.2% ischaemic cardiomyopathy, mean follow-up of 11.9±6.6 months). The overall survival was 69.6% (95% CI 62.6% to 76.2%). VT episodes and ICD shocks/month reduced by 81.5% (95% CI 64.2% to 94.8%) and 84.7% (95% CI 65.1% to 98.1%), respectively. However, only 23.1% (95% CI 10.7% to 37.7%) were VT-free at the end of follow-up. There were no significant differences in clinical outcomes between prospective and retrospective studies, nor between studies with high PTV and low PTV. A total of 352 AEs were reported in 280 patients, with a mean of 1.26 AE per patient. Of these AEs, 50.6% were classified as severe, though only 9.7% were likely STAR-related. STAR significantly reduces VT episodes and ICD shocks, offering symptomatic relief. However, high recurrence rates and severe AEs underscore the need for protocol optimisation and multidisciplinary collaboration to improve STAR's safety and efficacy in VT management.