PURPOSE To report the feasibility of magnetic resonance imaging-guided cardiac single fraction radioablation (MRgRA) in a patient with dilated cardiomyopathy and recurrent sustained ventricular tachycardia (VT) leading to electrical storms (ES). MATERIALS/METHODS A workflow to perform Stereotactic Arrhythmia Radioablation (STAR) on a hybrid MR-Linac with real-time tracking and beam-gating was established. Challenges of the MRgRA approach included: (a) the safety of a non-MR compatible cardiac implantable electronic device (CIED) in the MR-Linac field, (b) artefacts caused by the CIED and (c) respiratory motion management with cine-tracking of the moving heart. The specific absorption rate and slew rate of the MR-Linac were within the specifications of a MR-conditional CIED. Phantom measurements showed CIED distortion artefacts of less than 1.5 mm. During MR simulation, tracking could be established on the upper liver to avoid interference with the moving heart and CIED extinction artefacts. Areas of anatomical scarring and critical substrate were identified using invasive three-dimensional electroanatomical mapping of the clinical VT during electrophysiological studies and cardiac MR imaging/computed tomography to build a volumetric target. RESULTS A 71-year-old male patient with non-ischemic dilated cardiomyopathy and recurrent therapy-refractory sustained VT with repetitive implantable cardioverter-defibrillator (ICD) shocks was treated with a single fraction of 25 Gy @85% isodose, cine-tracking time was 46 min, beam-on time 24 min. 24 h post intervention the patient developed an aggravation of the clinical VT and prolonged ES. VT ceased following high-dose dexamethasone administration after 48 h. After this point, the patient remained without any episodes of sustained ventricular tachyarrhythmia requiring ICD interventions until the last follow-up at three months. CONCLUSION Real-time tracking and beam-gating were successfully applied in this first MRgRA to treat sustained VT.

中文翻译：

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第一次磁共振成像引导的持续性室性心动过速心脏放射消融

目的 报告磁共振成像引导的心脏单次放射消融 (MRgRA) 在扩张型心肌病和复发性持续性室性心动过速 (VT) 导致电风暴 (ES) 患者中的可行性。材料/方法 建立了在具有实时跟踪和光束门控的混合 MR-Linac 上执行立体定向心律失常放射消融 (STAR) 的工作流程。MRgRA 方法的挑战包括：(a) MR-Linac 场中非 MR 兼容的心脏植入式电子设备 (CIED) 的安全性，(b) CIED 引起的伪影和 (c) 使用电影进行呼吸运动管理追踪移动的心脏。MR-Linac 的特定吸收率和转换率在 MR 条件 CIED 的规格范围内。体模测量显示 CIED 失真伪影小于 1.5 毫米。在 MR 模拟过程中，可以在上肝脏建立跟踪，以避免干扰运动的心脏和 CIED 消光伪影。在电生理研究和心脏 MR 成像/计算机断层扫描期间，使用临床 VT 的侵入性三维电解剖映射来确定解剖疤痕和关键基质的区域，以建立体积目标。结果 一名患有非缺血性扩张型心肌病和复发性治疗难治性持续性室速的 71 岁男性患者接受重复植入式心脏复律除颤器 (ICD) 电击，单次 25 Gy @85% 等剂量，电影跟踪时间为 46 分钟，光束开启时间为 24 分钟。干预后 24 小时，患者出现临床 VT 加重和 ES 延长。48 小时后大剂量地塞米松给药后 VT 停止。在此之后，直到三个月的最后一次随访，患者仍然没有出现任何需要 ICD 干预的持续性室性快速性心律失常。结论 实时跟踪和光束门控成功应用于首个 MRgRA 治疗持续性 VT。