Elsevier

Heart Rhythm

Volume 17, Issue 8, August 2020, Pages 1241-1248
Heart Rhythm

Clinical
Ventricular Tachycardia
Stereotactic arrhythmia radioablation for refractory scar-related ventricular tachycardia

https://doi.org/10.1016/j.hrthm.2020.02.036Get rights and content

Background

Recently, stereotactic radiosurgery has been applied to arrhythmias (stereotactic arrhythmia radioablation [STAR]), with promising results reported in patients with refractory scar-related ventricular tachycardia (VT), a cohort with known high morbidity and mortality.

Objective

Herein, we describe our experience with STAR, detailing its early and mid- to long-term results.

Methods

This is a pilot prospective study of patients undergoing STAR for refractory scar-related VT. The anatomical target for radioablation was defined on the basis of the clinical VT morphology, electroanatomic mapping, and study-specific preprocedural imaging with cardiac computed tomography. The target volume was treated with a prescription radiation dose of 25 Gy delivered in a single fraction by CyberKnife in an outpatient setting. Ventricular arrhythmias and radiation-related adverse events were monitored at follow-up to determine STAR efficacy and safety.

Results

Five patients (100% men; mean age 63 ± 12 years; 80% with ischemic cardiomyopathy; left ventricular ejection fraction 34% ± 15%) underwent STAR. Radioablation was delivered in 82 ± 11 minutes without acute complications. During a mean follow-up of 12 ± 2 months, all patients experienced clinically significant mid- to late-term ventricular arrhythmia recurrence; 2 patients died of complications associated with their advanced heart failure. There were no clinical or imaging evidence of radiation-induced complications in the organs at risk surrounding the scar targeted by radioablation.

Conclusion

Despite good initial results, STAR did not result in effective arrhythmia control in the long term in a selected high-risk population of patients with scar-related VT. The safety profile was confirmed to be favorable, with no radiation-related complications observed during follow-up. Further studies are needed to explain these disappointing results.

Introduction

Stereotactic radiosurgery is a form of radiotherapy that is performed in a single session and focuses high-dose ionizing radiation beams from a collimated radiation source to a small localized area of the body. In contrast to traditional radiotherapy, which functions by disrupting cellular division, radiosurgery works by creating radiation-induced necrosis.1 Stereotactic radiosurgery is currently used for the treatment of various types of tumors in the head and neck, lung, abdomen, pelvis, and spine, with good local control rates and minimal side effects.2 Stereotactic arrhythmia radioablation (STAR) is the application of stereotactic radiosurgery for the noninvasive treatment of cardiac arrhythmias. STAR has been used to homogenize the scar in patients with structural heart disease and ventricular tachycardia (VT) that is refractory to antiarrhythmic drugs (AADs) and has failed radiofrequency catheter ablation (RFCA), with promising results.3, 4, 5, 6, 7, 8, 9, 10

In this report, we describe our experience with STAR, detailing its early and mid- to long-term results, which adds to the existing body of knowledge of radiation therapy applied to patients with ventricular arrhythmias.

Section snippets

Patient population

This was a prospective, single-arm, 2-center feasibility study of STAR for the treatment of refractory scar-related VT. Patients referred by an electrophysiologist to our center to be considered for radioablation were screened and considered for the study if they met all the following criteria: (1) presence of an implantable cardioverter-defibrillator (ICD), (2) ischemic or nonischemic cardiomyopathy with recurrent symptomatic VT that induced ICD shock(s) despite RFCA and/or AAD therapy, (3)

Results

Between January and June 2018, 6 patients were screened and enrolled in the study in 1 center. One patient was subsequently excluded because of preexisting chronic renal failure, with inability to undergo serial CT imaging with contrast at follow-up. Five patients underwent STAR, and their demographic and clinical characteristics are outlined in Table 1. An enrollment exception was made for 2 patients younger than 60 years, one of whom experienced recurrent sustained symptomatic VT episodes

Discussion

In this pilot study, STAR performed with CyberKnife, resulted in an initial decrease in ventricular arrhythmia burden in all patients, but significant recurrence was ineluctable by the end of 1-year follow-up. Of note, this is the first study to report unfavorable efficacy outcomes after radioablation, but it is important to note that follow-up times as well as definition of success and radiosurgical technologies differ among different studies, so a direct comparison is speculative at this

Conclusion

Despite good initial results, STAR did not result in effective ventricular arrhythmia control in the long term in a selected high-risk population of patients with scar-related VT. The safety profile of STAR was confirmed to be favorable, with no radiation-related complications observed during the first year of follow-up. Further studies are needed to explain these disappointing results.

References (24)

  • B.W. Loo et al.

    Stereotactic ablative radiotherapy for the treatment of refractory cardiac ventricular arrhythmia

    Circ Arrhythm Electrophysiol

    (2015)
  • P.S. Cuculich et al.

    Noninvasive cardiac radiation for ablation of ventricular tachycardia

    N Engl J Med

    (2017)
  • Cited by (0)

    This study was sponsored by CyberHeart.

    Drs Gardner and Maguire are employees of CyberHeart. Dr Gardner has intellectual and equity interests in CyberHeart. Drs Al-Ahmad and Zei received research and travel support from CyberHeart. The rest of the authors report no conflicts of interest.

    View full text