AUTHOR=Miszczyk Marcin , Sajdok Mateusz , Nożyński Jerzy , Cybulska Magdalena , Bednarek Jacek , Jadczyk Tomasz , Latusek Tomasz , Kurzelowski Radoslaw , Dolla Łukasz , Wojakowski Wojciech , Dyla Agnieszka , Zembala Michał , Drzewiecka Anna , Kaminiów Konrad , Kozub Anna , Chmielik Ewa , Grza̧dziel Aleksandra , Bekman Adam , Gołba Krzysztof Stanisław , Blamek Sławomir TITLE=Histopathological Examination of an Explanted Heart in a Long-Term Responder to Cardiac Stereotactic Body Radiotherapy (STereotactic Arrhythmia Radioablation) JOURNAL=Frontiers in Cardiovascular Medicine VOLUME=9 YEAR=2022 URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2022.919823 DOI=10.3389/fcvm.2022.919823 ISSN=2297-055X ABSTRACT=

Cardiac stereotactic body radiotherapy is an emerging treatment method for recurrent ventricular tachycardia refractory to invasive treatment methods. The single-fraction delivery of 25 Gy was assumed to produce fibrosis, similar to a post-radiofrequency ablation scar. However, the dynamics of clinical response and recent preclinical findings suggest a possible different mechanism. The data on histopathological presentation of post-radiotherapy hearts is scarce, and the authors provide significantly different conclusions. In this article, we present unique data on histopathological examination of a heart explanted from a patient who had a persistent anti-arrhythmic response that lasted almost a year, until a heart failure exacerbation caused a necessity of a heart transplant. Despite a complete treatment response, there was no homogenous transmural fibrosis in the irradiated region, and the overall presentation of the heart was similar to other transplanted hearts of patients with advanced heart failure. In conclusion, our findings support the theorem of functional changes as a source of the anti-arrhythmic mechanism of radiotherapy and show that durable treatment response can be achieved in absence of transmural fibrosis of the irradiated myocardium.