Low-Dose Radiation Therapy Demonstrates Potential for Treatment of Heart Failure

Millions of people are living with heart failure, a condition where the heart progressively loses its capacity to effectively circulate oxygenated blood throughout the body. Heart failure can arise from various causes, such as previous heart attacks, viral infections, or chronic arrhythmias like ventricular tachycardia, which is a dangerous abnormal heart rhythm. In a novel approach, a team comprising cardiologists and radiation oncologists has explored the use of radiation therapy, typically a cancer treatment, to manage ventricular tachycardia in heart failure patients. Initial studies on a small patient group and experimental models in mice suggest that low-dose radiation therapy could potentially enhance heart function in different heart failure forms. While further research is necessary to assess its application in heart failure patients, these findings imply that radiation may have broader and possibly advantageous impacts on hearts with significant inflammation than previously thought.

Researchers from Washington University in St. Louis (WUSTL, St. Louis, MO, USA) studied nine patients with ventricular tachycardia, conducting cardiac MRI scans before and after administering radiation treatment. The post-radiation MRIs revealed notable improvements in heart function, particularly the left ventricle's enhanced pumping ability, which circulates blood throughout the body. This improvement was observed mere days after treatment, indicating it was not solely due to arrhythmia reduction, which typically occurs over weeks and months. The team also examined low-dose radiation's effects on mice models with heart failure from three different causes. The results mirrored those seen in human patients: mice that received radiation therapy displayed better heart function, especially in the left ventricle. Notably, in mice with progressive heart failure, radiation treatment extended their survival, suggesting a direct correlation between improved heart function and increased survival.

In the mice with heart failure treated with radiation, there was a noticeable reduction in fibrosis or scar tissue, and a decrease in cardiac macrophages, an immune cell type known for driving heart inflammation. Generally, irradiated hearts showed fewer rapidly proliferating cells, such as immune cells and fibroblasts, which are known to exacerbate heart failure. Conversely, typical heart muscle cells rarely, if ever, divide. The research team plans to extend their investigation to patients already undergoing radiation therapy for ventricular tachycardia, aiming to delve deeper into radiation's impact on the heart. The current study, demonstrated through MRI, indicated improved heart function. The team now intends to conduct more comprehensive studies to ascertain if there is a corresponding decrease in inflammation in human hearts, akin to the findings in the mouse models.

“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,” said co-senior author and cardiologist Ali Javaheri, MD, PhD, an assistant professor of medicine. “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.”

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