Abstract
BackgroundSingle-session high-dose stereotactic radiotherapy (radiosurgery) is a new treatment option for otherwise untreatable patients suffering from refractory ventricular tachycardia (VT). In the initial single-center case studies and feasibility trials, cardiac radiosurgery has led to significant reductions of VT burden with limited toxicities. However, the full safety profile remains largely unknown.Methods/designIn this multi-center, multi-platform clinical feasibility trial which we plan is to assess the initial safety profile of radiosurgery for ventricular tachycardia (RAVENTA). High-precision image-guided single-session radiosurgery with 25 Gy will be delivered to the VT substrate determined by high-definition endocardial electrophysiological mapping. The primary endpoint is safety in terms of successful dose delivery without severe treatment-related side effects in the first 30 days after radiosurgery. Secondary endpoints are the assessment of VT burden, reduction of implantable cardioverter defibrillator (ICD) interventions [shock, anti-tachycardia pacing (ATP)], mid-term side effects and quality-of-life (QoL) in the first year after radiosurgery. The planned sample size is 20 patients with the goal of demonstrating safety and feasibility of cardiac radiosurgery in ≥ 70% of the patients. Quality assurance is provided by initial contouring and planning benchmark studies, joint multi-center treatment decisions, sequential patient safety evaluations, interim analyses, independent monitoring, and a dedicated data and safety monitoring board.DiscussionRAVENTA will be the first study to provide the initial robust multi-center multi-platform prospective data on the therapeutic value of cardiac radiosurgery for ventricular tachycardia.Trial registration numberNCT03867747 (clinicaltrials.gov). Registered March 8, 2019. The study was initiated on November 18th, 2019, and is currently recruiting patients.Graphic abstract
Highlights
Single-session high-dose stereotactic radiotherapy is a new treatment option for otherwise untreatable patients suffering from refractory ventricular tachycardia (VT)
Given unsatisfying success rates even after repeated catheter ablation, high incidences of toxicities of antiarrhythmic drugs and an increasing number of patients not eligible for catheter ablation, there is an urgent need for alternative, non-invasive treatment approaches for the treatment and prevention of refractory VT
As RA/cardiac radiosurgery (CRS) is a novel therapeutic approach, several issues regarding target volume definition, target volume transfer between cardiac and radiation oncology treatment systems, cardiac and respiratory motion assessment and management techniques, optimal target dose, and critical organ maximum and volume dose limitations and follow-up have to be further optimized in a dedicated interdisciplinary radioablation/cardiac radiosurgery (RA/CRS) team and the treatment has to be assessed in terms of safety and efficacy in close controlled and monitored clinical trials
Summary
An abnormal electrical focus or circuit in the ventricular myocardium corresponding to scar regions after myocardial infarction can be the origin of ventricular tachycardia (VT) [1, 2]. If drugs in adequate dosing fail to limit the VT episodes, catheter ablation of the arrhythmogenic substrate is the standard treatment option for VT arising around myocardial scars [1,2,3]. Given unsatisfying success rates even after repeated catheter ablation, high incidences of toxicities of antiarrhythmic drugs and an increasing number of patients not eligible for catheter ablation (due to co-morbidities or location of the VT substrate), there is an urgent need for alternative, non-invasive treatment approaches for the treatment and prevention of refractory VT. Stereotactic body radiotherapy (SBRT) in a single session to the heart, called radioablation (RA) or cardiac radiosurgery (CRS), may overcome the limitations of endocardial or epicardial thermal ablation energy deposition and offer a treatment alternative for otherwise untreatable patients [7]. As RA/CRS is a novel therapeutic approach, several issues regarding target volume definition, target volume transfer between cardiac and radiation oncology treatment (planning) systems, cardiac and respiratory motion assessment and management techniques, optimal target dose, and critical organ maximum and volume dose limitations and follow-up have to be further optimized in a dedicated interdisciplinary RA/CRS team and the treatment has to be assessed in terms of safety and efficacy in close controlled and monitored clinical trials
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