Contemporary ReviewCardiac radioablation—A systematic review
Introduction
Patients with ventricular arrhythmias are treated with antiarrhythmic drugs and invasive catheter ablation procedures in order to reduce the risk of recurrences. Unfortunately, failure of drugs and/or catheter ablation to prevent ventricular tachycardia (VT) and ventricular fibrillation (VF) is common and recurrence remains an import concern. Conventional VT ablation can be limited by incomplete or difficult target accessibility with subsequent arrhythmia persistence or recurrence after ablation.1 Stereotactic body radiotherapy, also known as stereotactic ablative radiotherapy, stereotactic arrhythmia radiotherapy, or radioablation, has the potential to overcome several limitations of conventional VT catheter ablation procedures.2, 3, 4
The effect of radioablation has been explored in several animal species with varying radiotherapy doses and outcomes. Experience in patients is limited but steadily growing since the first reported cases in 2014 and 2015.5,6
In this systematic review, we aim to summarize all the available evidence on radioablation in animals, patients, and extracted and perfused hearts in order to improve our understanding of the electrophysiological and histopathological effects of this novel treatment modality.
Section snippets
Methods
This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.7,8 The review is registered in the International Prospective Register of Systematic Reviews, CRD42019133212.
C.1. Search results and risk of bias
Of 473 unique records, 23 publications were included comprising 13 publications on animal data and 10 clinical publications. Only 1 prospective trial is currently available.3 Figure 1 shows a flowchart of the included publications. Risk of bias tools determined that most preclinical publications had a high risk of bias. Methodological quality tools indicated that clinical publications were mostly of low methodological quality. Online Supplemental Tables 1 and 2 present the results of the
Discussion
We performed a systematic review of the current knowledge base of cardiac radioablation in animals, extracted and perfused hearts, and patients. Although the current quality of evidence is not high enough to draw robust conclusions, the data presented in this review suggest that in animals, (1) radioablation is able to induce a change in electrophysiological parameters (ie, a decrease in voltage or conduction delay) within target areas, (2) radioablation is able to decrease ventricular
Conclusion
Preclinical and clinical evidence on the efficacy and safety of radioablation is limited in both quantity and quality. The results of the only clinical prospective trial show that radioablation is a promising treatment modality for patients with therapy refractory VT. Further research regarding the mechanism of action, optimum doses, and long-term efficacy and safety is crucial to making this novel therapy a success.
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2023, Physics and Imaging in Radiation Oncology
Dr Blanck reports to have been an employee of CyberHeart from 2008 to 2010, though he reports no financial ties or obligations or conflict of interest to or with the company or its legal predecessor Varian. Dr de Groot is supported by a personal grant from Nederlandse Organisatie voor Wetenschappelijk Onderzoek Zorgonderzoek en Medische Wetenschappen (NWO ZonMW) 016.146.310 and reports research grants to his institution from AtriCure, Boston Scientific, Medtronic, and Abbot and consultancy/speaker fees from AtriCure, Bayer, Daiichi Sankyo, Novartis Medtronic, and Servier. Dr Robinson reports research grants from Elekta, Merck, and Varian Medical Systems and consulting and speaking honoraria from AstraZeneca, EMD Serono, and Varian Medical. Dr Slotman reports research grants and speaker fees from Varian Medical Systems and ViewRay. Dr Zei reports research support from CyberHeart and Biosense Webster, advisory board work for Varian, and consultancy fees from Abbott and Boehringer Ingelheim. The rest of the authors report no conflicts of interest.