In mice with heart failure, radiation therapy demonstrated improved heart function, specifically in the left ventricle, and reduced inflammation in the heart.
Radiation therapy, typically used to treat cancer, could potentially be used to treat individuals with ventricular tachycardia, a life-threatening abnormal heart rhythm, according to investigators from the Washington University School of Medicine in St. Louis.
The investigators of the study found that there were cardiac effects in a small number of patients and aimed to model the effects of low-dose radiation in mice with heart failure (HF). They determined that low-dose radiation therapy improved heart function for various forms of HF, according to a press release.
“The radiation therapy used to treat ventricular tachycardia is targeted to a specific location in the heart; however, a large portion of the rest of the heart gets a low-dose exposure,” Ali Javaheri, MD, PhD, an assistant professor of medicine, said in the press release. “We wanted to understand the effects of that low-dose radiation on these patients’ hearts. There was concern that it could be harmful to overall heart function, even though it treats dangerous arrhythmia. We were surprised to find the opposite: heart function appeared to be improved after radiation therapy, at least in the short term.”
Investigators noted that more research needs to be done to evaluate radiation therapy for patients with HF, but the results of this study demonstrate that the effects of radiation could potentially benefit injured hearts with high levels of inflammation. The results showed that low-dose radiation does reduce the number of inflammatory immune cells in the heart, according to the press release.
In the study, the investigators evaluated a group of 9 individuals with ventricular tachycardia using a cardiac magnetic resonance imaging (MRI) before and after radiation treatment. MRIs showed that the patients' hearts improved in pumping capacity in the left ventricle, which is responsible for supplying blood to the body. According to the press release, the improvement was seen a few days after treatment, so investigators believe that it was unlikely to be due to the reduction of arrhythmia, which happens more gradually.
Furthermore, the investigators evaluated the effects of similar low-dose radiation on the hearts of mice with HF due to 3 different causes. They found similar effects that were observed in humans, demonstrated improved heart functions in the mice that received radiation therapy, specifically in the left ventricle. Additionally, in the mice, the therapy increased their survival, showing that the improved heart function does translate to improved survival, according to the press release. In mice with HF, investigators also found that radiation reduced fibrosis and cardiac macrophages, a type of immune cell associated with inflammation in the heart.
“The effect we see in these hearts is likely more complex than a simple reduction of rapidly dividing inflammatory immune cells. We are continuing our research to delve more deeply into what else may be happening, but we have been pleasantly surprised to see evidence that low-dose radiation in these hearts may reduce inflammation and help remodel the heart in a way that is beneficial,” Carmen Bergom, MD, PhD, an associate professor of radiation oncology, said in the press release.
The investigators plan to continue to analyze the effects of radiation therapy for patients with ventricular tachycardia, including the development of advanced studies to determine if the evidence of reduced inflammation in mice translates to humans, according to the press release. The study’s full findings were published in Med.
Radiation therapy may be potential heart failure treatment. News release. EurekAlert. November 28, 2023. Accessed December 1, 2023. https://www.eurekalert.org/news-releases/1009269