If you have ventricular tachycardia, your doctor may give you medicine to slow your heart rate down. You might also need a catheter ablation. In this procedure, a doctor threads a thin tube through an artery, using heat or cold to make a scar on your heart. This scar may stop the signals that are causing your abnormal heart rhythm. You could need surgery, If these don’t work or your abnormal heart rhythm comes back, doctors now have another experimental option that uses radiation. It’s called cardiac stereotactic body radiation therapy (SBRT).
What Is Stereotactic Body Radiation Therapy for Ventricular Tachycardia?
SBRT is mostly used to treat cancer. The benefit of SBRT, both for treating cancer and your heart, is that doctors can use it to deliver radiation very precisely. Because of this, doctors can use it to give radiation in bigger doses without damaging other tissues. It’s often used to treat small cancers or spots where cancer has spread to the lungs, liver, or other places in the body.
Doctors deliver SBRT using a device called a linear accelerator. It forms a beam of fast-moving particles. A computerized system allows doctors to deliver the radiation beam to just the right place and in just the right shape.
In cardiac SBRT, doctors use the same SBRT procedure used for cancer to deliver radiation to your heart. They’ll try to avoid damaging your lungs, stomach, or other parts of your heart. The whole procedure takes an hour or less and you can leave the same day. The goal is to target the right place in the heart to stop your abnormal heart rhythm. Doctors think it works in a way that’s similar to catheter ablation, but using a procedure that’s less invasive. Cardiac SBRT has potential to reach places catheter ablation can’t and with less risk. But its use for treating ventricular tachycardia is still new and considered experimental.
How Well Does Radiation Therapy Work for Ventricular Tachycardia?
Two studies suggest radiation therapy works well. But the studies are small, so it’s too early to say how well it works and for how long. One study in 5 people from 2015 looked at how well 11-18 minutes of focused radiation worked. People in the study had more than 6,500 episodes of tachycardia in the 3 months before the radiation. The researchers used imaging to target specific areas on the heart while people were awake.
In the 6 weeks after radiation, those in the study had 680 episodes of ventricular tachycardia. After that, they had even fewer. The study reports just four episodes consistent with almost no ventricular tachycardia. The abnormal heart rhythms were reduced by 99.99%.
Another phase I/II trial looked at radiation therapy in 19 people with ventricular tachycardia that hadn’t gotten better with other treatments. Researchers wanted to know if it was safe and if it would work. In the first 3 months, two people in the study had a serious adverse event related to treatment. But the number of tachycardia episodes dropped from 119 to three after the radiation.
One person dropped out of the study. But for most of those in the study (90%), ventricular tachycardia went down by 75%. Survival at 6 months was about 90% and 72% after a year. Overall, the researchers reported that radiation therapy appeared to work with some short-term risks. It also allowed people to take less medicine and improved quality of life. At least one study has shown radiation therapy kept working for at least 2 years in most people. So early studies are encouraging, but they’re too small to say for sure how well radiation therapy works.
What Are the Side Effects of Radiation Therapy for Ventricular Tachycardia?
The studies so far are small, but most people seem to do well. Radiation therapy also reduces ventricular tachycardia in most people. But radiation therapy on the heart might cause damage that doesn’t show up until later. One reason this could happen is because of movement as your heart beats and as you breathe in and out. Even though SBRT can hit a precise target, this movement can lead to damage in other heart tissues. Some people who have cardiac SBRT also feel sick to their stomach. Researchers say more study is needed to understand the effects on the heart and how it works long term.
How Does Radiation Therapy Affect the Heart in Ventricular Tachycardia?
It’s not clear exactly how radiation affects the heart. The idea at first was to create a scar in the right place. This is how catheter ablation works. Scarring makes heart tissue stop responding to signals to stop an abnormal rhythm. A more recent study supports the idea that radiation can work to get rid of ventricular tachycardia. But it’s not clear if it works the way doctors had expected.
Radiation can make a scar on the heart. But the study found that the radiation dose doctors have used for the heart isn’t enough to make a scar. Instead, the radiation may “reprogram” heart tissue so it carries electrical signals differently. This may happen from complex changes at the molecular level that affect how the heart tissue works. The researchers said that the radiation actually works too quickly for scarring to explain it. As doctors understand this better, it could lead to even better ways to change abnormal heartbeats with radiation.
How Can I Get Radiation Therapy for Ventricular Tachycardia?
Right now, radiation isn’t a standard option to treat your irregular heartbeat. Doctors recently issued recommendations for cardiac SBRT for ventricular tachycardia. It’s generally only an option now if you don’t get better with other treatments, including catheter ablation. Experts say cardiac radiation therapy remains experimental. So its safety and effectiveness aren't yet proven.
It’s best to get it as part of a clinical trial or registry at a specialized center with experts in both irregular heartbeats and SBRT. One of the reasons it’s a challenge is because the heart is a moving target. Experts say it shouldn’t be used except in people who already had a catheter ablation that didn’t work. It might also be an option if you can’t have a catheter ablation.
If you’re interested in radiation therapy for your ventricular tachycardia, ask your doctor if it might be an option. It most likely isn’t unless other procedures aren’t working for you or you can’t have a catheter ablation. You could also look to see if a clinical trial is ongoing at a major medical center near where you live. As researchers get more data – and if it continues to look safe and effective compared to other options – radiation therapy might one day get approved for correcting irregular heartbeats in some cases. For now, it looks promising, but isn’t an option for most people.
