Electrical storm treated with radiation therapy in a patient with ischemic cardiomyopathy and left ventricular thrombus

M. Lemoine (Hamburg)¹, D. Krug (Kiel)², M. Grohmann (Hamburg)³, O. Blanck (Kiel)², C. Petersen (Hamburg)³, N. Matthes (Hamburg)⁴, D. Ismaili (Hamburg)¹, K. Govorov (Hamburg)¹, M. L. Benesch Vidal (Hamburg)⁵, A. Welcker (Hamburg)⁴, P. Kirchhof (Hamburg)⁶, A. Metzner (Hamburg)⁷, A. Rillig (Hamburg)⁷, F. Ouyang (Hamburg)¹, B. Reißmann (Hamburg)^8
1Universitäres Herz- und Gefäßzentrum Hamburg Klinik für Kardiologie Hamburg, Deutschland; ²Universitätsklinikum Schleswig-Holstein Klinik für Strahlentherapie Kiel, Deutschland; ³Universitätsklinikum Hamburg-Eppendorf Klinik für Strahlentherapie Hamburg, Deutschland; ⁴Universitätsklinikum Hamburg-Eppendorf Klinik für Kardiologie Hamburg, Deutschland; ⁵Universitäres Herz- und Gefäßzentrum Hamburg Klinik und Poliklinik für Kardiologie Hamburg, Deutschland; ⁶Universitäres Herz- und Gefäßzentrum Hamburg Klinik für Kardiologie Lübeck, Deutschland; ⁷Universitäres Herz- und Gefäßzentrum Hamburg Klinik für Kardiologie mit Schwerpunkt Elektrophysiologie Hamburg, Deutschland; ⁸Universitäres Herz- und Gefäßzentrum Hamburg Allgemeine und Interventionelle Kardiologie Hamburg, Deutschland

Background:
Electrical storm remains a major therapeutic challenge. When pharmacologic and interventional strategies fail or are contraindicated, stereotactic arrhythmia radiotherapy (STAR) has emerged as a noninvasive rescue option for refractory ventricular tachycardia (VT).
Case summary:
We report on a 80-year-old man with ischemic cardiomyopathy presented with recurrent electrical storm due to VT refractory to long-term amiodarone and maximum-dose beta-blocker therapy. His medical history included two myocardial infarctions involving the left anterior descending 25 years before and circumflex arteries 15 years before, resulting in severely reduced left ventricular (LV) ejection fraction of 15% with LV anterior aneurysma, left bundle branch block and cardiac resynchronization therapy with defibrillator and a newly diagnosed apical LV thrombus. 
The patient developed incessant monomorphic VT at 110 bpm (Figure), which was tolerated hemodynamically, but shifted the patient to NYHA IV. Manual antitachycardia pacing could transiently terminate VT, but recurrences occured after a few hours. Neither high-dose oral (400 mg/d) and intravenous amiodarone, nor the combination of amiodarone and lidocaine, nor bilateral stellate ganglion blockade could suppress the electrical storm. Catheter ablation was considered too high-risk due to LV thrombus and was refused by the patient.
STAR was planned as a last-resort option. Since endocardial mapping data were unavailable, contrast-enhanced cardiac CT images were processed using the InHEART software to segment the LV myocardium, delineate scar regions, and define the target volume (Figure). To further refine the target, 12-lead ECG recordings of VT and ECGs obtained during right ventricular - and LV pacing were analyzed. STAR was planned with 4D-computed tomography using an Internal Target Volume - approach and delivered with 25 Gy under Cone Beam Computed Tomography and Surface Guided Radiation Therapy -guidance with a dose of 25 Gy with integrated sparing of the stomach.
Following STAR, the electrical storm stopped immediately, and continuous monitoring for five days showed no recurrence. The treatment was well tolerated with no discernible adverse events apart from mild fatigue. During three months of follow-up under 200 mg/d amiodarone, the patient remained asymptomatic and free from VT, with unchanged LV function and functional status (NYHA class II-III). A CT-scan showed no signs or pericardial effusion or pneumonitis.
Conclusion:
This case illustrates the complexity of managing electrical storm in end-stage ischemic cardiomyopathy with LV thrombus and highlights the evolving role of multimodal therapy. The integration of advanced imaging and 3D electroanatomical modeling with InHEART enabled precise STAR target planning, representing a promising approach for patients unsuitable for ablation.


Clinical ventricular tachycardia and a CT-based reconstruction of the heart with analysis of vital LV wallthickness and target zone of STAR.