Ablative Radiotherapy as a Noninvasive Alternative to Catheter Ablation for Cardiac Arrhythmias

Abstract

Purpose of review: Stereotactic radioablation is a commonly utilized technology to noninvasively treat solid tumors with precision and efficacy. Using a robotic arm mounted delivery system, multiple low-dose ionizing radiation beams are delivered from multiple angles, concentrating ablative energy at the target tissue. Recently, this technology has been evaluated for treatment of cardiac arrhythmias. This review will present the basic underlying principles, proof-of-principle studies, and clinical experience with stereotactic arrhythmia radioablation.

Recent findings: Most recently, stereotactic radioablation has been used to safely and effectively treat a limited number of patients with malignant arrhythmias, including ventricular tachycardia (VT) and atrial fibrillation (AF). Treatment protocols, outcomes, ongoing studies, and future directions will be discussed. Stereotactic radioablation is a well-established technology that has been shown to be a safe and effective therapy for patients with drug-refractory cardiac arrhythmias, including VT and AF. Further clinical evaluation to define safety and efficacy in larger populations of patients is needed.

Keywords: Ablation; Atrial fibrillation; Noninvasive; Radiosurgery; Stereotactic; Ventricular tachycardia.

Fig. 1

Delivery of 25 Gy single-dose radiotherapy via a stereotactic device in a porcine model. Targeting of the right pulmonary vein antrum results in electrical block of the pulmonary veins, as demonstrated by (i–ii) exit block seen with high-output pacing in the right pulmonary veins via a circular mapping catheter, (iii) electroanatomic mapping evidence of low voltage, and (iv) histological staining of anatomic specimens demonstrating evidence of transmural fibrosis at the site of ablation

Fig. 2

Carbon particle therapy is delivered to the AV node. (i) AV block is demonstrated electrocardiographically 17 weeks after carbon particle treatment. (ii) Treatment isodose curves shown superimposed on a coronal CT image of the central cardiac structures. Concentrated dosing is shown at the presumed site of the AV node. (Figures are courtesy of H. Immo Lehmann, MD. They are from: Lehmann HI, et al. Sci Rep. 2016 Dec 20;6:38895. doi: 10.1038/srep38895) [17]

Fig. 3

Treatment of a scar-based VT is shown. In part i, PET imaging demonstrating dense infarct in the inferobasal wall of the left ventricle (LV) is shown. The intended treatment plan is superimposed, along with planned delivery beams in three dimensions, as well as planned isodoses. In part (ii), the treatment software display is shown, with CT imaging of the intended inferobasal LV target shown. Superimposed on the CT image are delivered radiation beams and delivered isodoses