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Single dose of radiation therapy can make your heart ‘younger.’ Here’s what it’s for

Benefits of the treatment can manifest in a few days to weeks and last for at least two years.
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A single dose of radiation therapy typically used to treat cancer can “reprogram” your heart into a younger and healthier version of itself, new research shows. The biological renovation can replace a more invasive procedure to fix electrical problems in the heart that cause arrhythmia, or irregular heartbeat. (Getty Images | iStockphoto)

A single dose of radiation therapy typically used to treat cancer can “reprogram” your heart into a younger and healthier version of itself, new research shows. The biological renovation can replace a more invasive procedure to fix electrical problems in the heart that cause arrhythmia, or irregular heartbeat.

Experiments on donated hearts from people who died or received transplants showed these benefits can manifest in a few days to weeks after the procedure and last for at least two years, according to the study published Sept. 24 in the journal Nature Communications.

Additional research done in laboratory mice suggests a lower dose of radiation can achieve the same effect, meaning this kind of therapy may help people with a wide range of cardiac arrhythmias in a much ​shorter and noninvasive way. The new study focused on those with a condition called refractory ventricular tachycardia (VT).

Radiation therapy helped hearts in a few days to weeks

Usual treatment for VT involves a procedure called catheter ablation, during which doctors thread a thin tube into the heart that burns surrounding tissues. Over time, these “injuries” create scarring that blocks abnormal and overactive electrical signals that cause /​an/​ irregular heartbeat.

What surprised researchers was that hearts with arrhythmias “experienced large improvements” after radiation therapy in a few days to weeks, as opposed to the months it takes for the more-invasive procedure to work. That’s because it takes time for scar tissue to form in the heart.

This means the radiation treatment works “just as well, if not better” than the invasive procedure even without scarring.

“We saw that scar tissue alone could not explain the remarkable clinical effects, suggesting that radiation improves the arrhythmia in some other way, so we delved into the details of that,” senior author and cardiologist Dr. Stacey Rentschler, an associate professor of medicine, developmental biology and biomedical engineering at the Washington University School of Medicine in St. Louis, said in a news release.

So, what could explain the clinical benefits?

Researchers discovered radiation treatments made heart muscle cells begin to express different genes, particularly those involved with a pathway called “Notch.” This pathway plays a critical role in the formation of the heart’s electrical system during early development.

Just a single dose of radiation “temporarily activates” Notch, which in turn increases the number of sodium ion channels in the heart; the more of these channels present, the more likely a heart will beat normally.

This is an important finding because Notch is usually turned off in adult hearts. That’s why researchers say the therapy can make your heart “younger.”

“As part of the body’s response to that injury [from radiation therapy], cells in the injured portion of the heart appear to turn on some of these early developmental programs to repair themselves,” study co-author and radiation oncologist Dr. Julie Schwarz, a professor of radiation oncology at WashU Med, said in the news ​release. “It’s important to understand how this works because, with that knowledge, we can improve the way we’re treating these patients and then apply it to other diseases.”

The team says Notch has a big role in reducing arrhythmias, but it’s not the only player in the game. Future research will investigate how and why radiation triggers the heart to transform into a younger, healthier version of itself.

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