3457 - Stereotactic Radioablation to Ventricular Tachycardia: Prospective Phase I Study in Asian Country

02:30pm - 03:45pm PT

Hall F

Screen: 21

POSTER

Presenter(s)

Mariko Kawamura, MD, PhD - Nagoya University hospital, Nagoya, Aichi

M. Kawamura¹, M. Shimojo², Y. Inden², T. Kamomae¹, Y. Oie¹, Y. Kozai¹, M. Okumura³, N. Nagai¹, R. Yasui¹, S. Ishihara¹, T. Yamada¹, and S. Naganawa¹; ¹Department of Radiology, Nagoya University Graduate School of Medicine, Nagoya, Japan, ²Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan, ³Nagoya University Graduate School of Medicine, Nagoya, Japan

Purpose/Objective(s):

Stereotactic body radiation therapy (SBRT) for ventricular tachycardia (VT) is emerging, but data in Asian populations, particularly with non-ischemic VT, are limited. This prospective phase I trial evaluated the safety and efficacy of SBRT for refractory VT in Japanese patients.

Materials/Methods:

A single-arm, single-center feasibility study enrolled patients =18 years with recurrent VT post-ablation, =3 episodes/3 months despite antiarrhythmic drugs, and unsuitable for further ablation. SBRT was delivered as 25Gy in one fraction (D95%) using electrical anatomical mapping (EAM) data merged with planning CT for targeting. Primary endpoint: 1-year safety. Secondary endpoints: efficacy and long-term safety.

Results:

Three patients (2 with non-ischemic cardiomyopathy: 1 hypertrophic cardiomyopathy [HCM], 1 dilated cardiomyopathy [DCM]; 1 with ischemic cardiomyopathy [ICM]) were enrolled and completed 1-year follow-up. Both HCM and DCM patients presented with electrical storms before treatment, demonstrating the severity of their VT burden. All patients had undergone =3 prior catheter ablation procedures, highlighting the refractory nature of their arrhythmia. EAM data from the most recent ablation at our institution, combined with contrast-enhanced magnetic resonance imaging (MRI), guided the SBRT targeting. Prior to SBRT, all patients underwent single-photon emission computed tomography (SPECT) and echocardiography for baseline functional assessment. No =Grade 2 acute radiation-related side effects were observed, indicating the safety of the procedure. All patients were alive at 1 year. The HCM patient was VT-free at 1 year, with an improvement in left ventricular ejection fraction (LVEF) from 50% to 60%, likely attributable to the elimination of VT burden. The DCM and ICM patients demonstrated a reduction in VT episodes, but no improvement in LVEF was observed. While echocardiography showed no significant changes in regional wall motion, quantitative SPECT and heart risk view-function analysis suggested progressive myocardial damage at 1 month and 1 year post-SBRT, indicating potential long-term effects of radiation. The DCM patient experienced an increase in VT episodes at 1 year (though less frequent than pre-SBRT), necessitating repeat catheter ablation, which revealed slow VT within the irradiated area, suggests that this may be the mechanism of efficacy of SBRT.

Conclusion:

SBRT for refractory VT using 25Gy in one fraction appears safe in Asian patients in the short term. HCM without heart failure may be a promising candidate for curative intent, while end-stage heart failure may be less suitable. Palliative VT reduction may still be beneficial. Continued data collection is warranted.