Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Jun;18(6):e013684.
doi: 10.1161/CIRCEP.124.013684. Epub 2025 May 20.

STAR Locally Prolongs Effective Refractory Period and Increases Ventricular Tachycardia Cycle Length Without Short-Term Scar Formation or Functional Decline: Insights From a Translational Porcine Model Study

Brian Zenger  1   2 , Timothy W Smith  1   2 , Stephanie Hicks  1   2 , Sherwin Ng  1   2 , Todd Pavek  3 , Nels Knutson  2   4 , Pamela P Samson  2   4 , Jie Zheng  5 , Caleb Berberet  5 , El-Sayed H Ibrahim  6 , Vinay Jani  7 , James Tabor  1   2 , Leslie D Wilson  3 , Samuel D Jordan  1   2 , Luke C Marut  2   4 , Aryan Kumar  1   2 , Sneha Manikandan  1   2 , Ali Javaheri  1   2   8 , Carmen Bergom  2   4 , Julie K Schwarz  2   4 , Patrick M Boyle  7   9 , Geoffrey D Hugo  2   4 , Phillip S Cuculich  1   2 , Cliff Robinson  2   4 , Christian Zemlin  10 , Stacey L Rentschler  1   2   11
Affiliations

STAR Locally Prolongs Effective Refractory Period and Increases Ventricular Tachycardia Cycle Length Without Short-Term Scar Formation or Functional Decline: Insights From a Translational Porcine Model Study

Brian Zenger et al. Circ Arrhythm Electrophysiol. 2025 Jun.

Abstract

Background: Stereotactic arrhythmia radiotherapy (STAR) has emerged as a potential therapy for treatment-refractory ventricular tachycardia (VT). However, the mechanisms underlying STAR efficacy, such as scar or other electromechanical changes, are still unclear. The goal of this study was to develop a translational porcine model of ischemic monomorphic VT treated with STAR to examine the physiological changes after a typical clinical STAR treatment.

Methods: We treated a previously validated porcine model of monomorphic VT after myocardial infarction with a clinically derived STAR protocol. A dose of 25 Gy was prescribed to the planning target volume and 35 Gy to the clinical target volume (regions of scar), while controls underwent a sham STAR treatment. All investigators in the study were blinded except the treating investigator. The primary study outcome was VT inducibility at 6 weeks post-STAR. Animals underwent pre- and post-STAR cardiac magnetic resonance imaging to quantify myocardial scar and function, as well as body surface mapping. Six weeks post-STAR, animals underwent a VT induction study, and tissue was harvested for optical mapping and histological analysis.

Results: Six animals completed the study, which ended before finishing enrollment because all animals had inducible VT. We found a significantly longer local effective refractory period in the left ventricular apex and longer VT cycle lengths in STAR-treated animals compared with controls (P<0.05). We found no difference in myocardial scar burden, mechanical function, or body surface recordings when comparing pre- and post-STAR.

Conclusions: Our data suggest a novel therapeutic mechanism of STAR driven by increasing the effective refractory period in locally treated areas, corresponding to increased tissue wavelength. Our results corroborate clinical case reports and anecdotal evidence that STAR increases VT cycle length. Importantly, these effects were not mediated by an increase in myocardial scar burden. However, our studies do not examine the long-term effects of STAR.

Keywords: animal model; cardiac electrophysiology; myocardial infarction; radiotherapy; ventricular tachycardia.

PubMed Disclaimer

Conflict of interest statement

Dr Hugo receives research funding from Varian Medical Systems, Viewray, Mevion Medical Systems, Siemens Healthineers and consulting fees from Varian Medical Systems, Patents/IP Licensed to Varian Medical Systems. Dr Rentschler receives research funding from Varian Medical Systems. Dr Robinson receives grants and research funding from Varian, AstraZeneca, Merck. Honoraria; Varian, AstraZeneca, EMD Serono, Radialogica and compensation/payment from EmpNia. He owns stock from Quantaras, Radialogica and holds copyright/patent/license/royalty from Varian. He has stock options for Radialogica, Quantaras and is Chief Medical Officer for Radialogica. Dr Cuculich receives grant/research funding from Varian. He holds copyright/patent/license/royalty from Varian. The other authors report no conflicts.

Similar articles

See all similar articles

References

    1. Cuculich PS, Schill MR, Kashani R, Mutic S, Lang A, Cooper D, et al. Noninvasive Cardiac Radiation for Ablation of Ventricular Tachycardia. N Engl J Med 2017;377:2325–2336. doi:10/gcrcks. - PMC - PubMed
    1. Robinson CG, Samson PP, Moore KMS, Hugo GD, Knutson N, Mutic S, et al. Phase I/II Trial of Electrophysiology-Guided Noninvasive Cardiac Radioablation for Ventricular Tachycardia. Circulation 2019;139:313–321. doi:10/gr8cmr. - PMC - PubMed
    1. Martí-Almor J, Jiménez-López J, Rodríguez de Dios N, Tizón H, Vallés E, Algara M. Noninvasive ablation of ventricular tachycardia with stereotactic radiotherapy in a patient with arrhythmogenic right ventricular cardiomyopathy. Rev Espanola Cardiol Engl Ed 2020;73:97–99. doi:10/gr8cn7. - PubMed
    1. Chin R, Hayase J, Hu P, Cao M, Deng J, Ajijola O, et al. Non-invasive stereotactic body radiation therapy for refractory ventricular arrhythmias: an institutional experience. J Interv Card Electrophysiol 2021;61:535–543. doi: 10.1007/s10840-020-00849-0. - DOI - PubMed
    1. Arkles J, Markman T, Trevillian R, Yegya-Raman N, Garg L, Nazarian S, et al. One-Year Outcomes Following Stereotactic Body Radiotherapy for Refractory Ventricular Tachycardia. Heart Rhythm 2023;0. doi: 10.1016/j.hrthm.2023.10.005. - DOI - PubMed

LinkOut - more resources