Key result
Stereotactic arrhythmia radioablation yields no severe adverse events at 12 months and reduces VT burden.
Why the study?
The 1 year safety and efficacy of stereotactic arrhythmia radioablation delivered using the CyberKnife system for refractory VT in Japanese patients required prospective evaluation.
Does stereotactic arrhythmia radioablation (STAR) using the CyberKnife system safely reduce ventricular tachycardia burden without causing Grade ≥ 3 adverse events in Japanese patients with RFCA-refractory ventricular tachycardia and structural heart disease?
Does stereotactic arrhythmia radioablation (STAR) using the CyberKnife system safely reduce ventricular tachycardia burden without causing Grade ≥ 3 adverse events in Japanese patients with RFCA-refractory ventricular tachycardia and structural heart disease?
This initial Japanese pilot study demonstrates the 1-year safety and preliminary feasibility of CyberKnife-based stereotactic arrhythmia radioablation for refractory VT, while highlighting a risk of late LVEF decline when irradiating large target volumes in patients with preserved baseline myocardial function.
Supports short-term safety of CyberKnife STAR in refractory VT; extends prior trials but leaves open LVEF risks with large targets.
Purpose This prospective study evaluated the 1 year safety and efficacy of stereotactic arrhythmia radioablation (STAR) delivered using the CyberKnife system for refractory ventricular tachycardia (VT) in Japanese patients, in accordance with a prespecified clinical protocol. Materials and methods Three male patients with radiofrequency catheter ablation (RFCA)-refractory VT and structural heart disease, namely hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and ischemic cardiomyopathy (ICM), were enrolled. A single fraction of 25 Gy was delivered to the target volume defined by multimodal image fusion. The primary endpoint was the absence of Grade ≥ 3 treatment-related adverse events within 12 months. Results The primary endpoint was achieved, with no acute or subacute Grade ≥ 3 toxicities observed in any patient during the first year. Although all patients experienced a reduction in VT burden, the clinical course differed by etiology. Cases 2 (DCM) and 3 (ICM) showed typical responses, including delayed efficacy and late recurrence requiring repeat RFCA. In contrast, Case 1 (HCM), with a substantially larger target volume (133 mL), showed a rapid response but a progressive decline in left ventricular ejection fraction by myocardial scintigraphy, from 59.7% to 40.0%, during the 24 month extended follow-up. Conclusion STAR demonstrated preliminary feasibility as a noninvasive salvage therapy for refractory VT in this initial Japanese pilot experience. However, the late functional decline observed in Case 1 highlights the need for long-term follow-up and myocardium-sparing techniques for large target volumes. (jRCTs042230030).
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Kawamura et al. (2026) studied Radiofrequency catheter ablation-refractory ventricular tachycardia with structural heart disease (n=3). Stereotactic arrhythmia radioablation (STAR) using CyberKnife was evaluated on Absence of Grade ≥ 3 treatment-related adverse events (CTCAE v5.0) within 12 months. Stereotactic arrhythmia radioablation (25 Gy) resulted in 0% Grade ≥3 adverse events at 12 months and reduced VT burden in all 3 patients, though 1 patient had LVEF decline from 59.7% to 40.0% at 24 months.
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