Stereotactic body radiation therapy: A new approach for resistant ventricular tachycardia

Ventricular tachycardia (VT) originates from regions of scarring in the heart left by prior heart attack, myocarditis, or other pathologies. “Similar to other arrhythmias, VT can cause a range of symptoms, from palpitations to worsening heart failure or syncope, but it's relatively unique in that it can result in sudden cardiac death,” Timothy Markman, MD, Assistant Professor of Medicine in Cardiovascular Medicine at Penn Medicine.

Dr. Markman, joined by Keith Cengel, MD, PhD, a Professor of Radiation Oncology at Penn Medicine, appeared on the Penn Medicine Physician Interviews podcast to discuss current treatments for ventricular tachycardia (VT) and RADIATE-VT, a novel clinical trial.

Ventricular tachycardia treatments

A variety of treatments are used to manage VT:

• Implantable cardioverter defibrillators can prevent sudden death when VT occurs, but don’t prevent the arrhythmia from happening.
• Antiarrhythmic medications have the advantage of being noninvasive, but they can cause significant side effects, and their efficacy is mixed.
• Catheter ablation is more effective than antiarrhythmic medications, but it carries risks as a minimally invasive procedure and may not be an option for patients with weak hearts or other significant comorbidities. Moreover, VT sometimes originates in regions of the heart that are hard to reach via catheter.

RADIATE-VT trial of SBRT in VTach

In the novel multisite RADIATE-VT clinical trial, Penn Medicine researchers are now exploring an investigational treatment, stereotactic body radiation therapy (SBRT), as an option when traditional treatments have failed to correct VT.

SBRT ablates cardiac tissue using radiotherapy, building on more than a century of radiotherapy in the cancer space, Dr. Cengel says. As technical capabilities have improved, physicians] can now precisely target areas in the chest as small as one centimeter with radiation.

“It’s a very accurate and dependable way of delivering radiation,” Dr. Cengel says. “Instead of aiming at a tumor in the lung, we’re now aiming at an electrical circuit in the heart.”

Penn Medicine physicians have been using SBRT for VT on an investigational basis for more than five years and are now participating in the RADIATE-VT clinical trial. The study is testing cardiac radioablation in patients for whom no other treatments have worked, including previous catheter ablations.

Participants are randomized to receive either an additional standard-of-care catheter ablation or SBRT. In SBRT, the radiotherapy dose is similar to that used for a single fraction treatment of lung cancer, so the researchers have a good sense of its safety in the chest, says Dr. Cengal.

RADIATE-VT will assess outcomes, side effects, and quality of life for patients with VT.

Testing SBRT in RADIATE-VT

Given the potential risks of radiotherapy, SBRT is not for everyone. “If you are a very healthy patient who is doing well otherwise, who has an ablatable VT circuit, radiation is not likely to be appropriate at any time,” Dr. Cengel emphasizes. But patients with life-threatening VT who have exhausted their other options may be well served by SBRT and may be eligible to participate in the RADIATE-VT trial.

The Penn Medicine team has extensive experience managing VT using traditional therapies. “With antiarrhythmic medications and catheter ablation, we're able to effectively treat these arrhythmias in the vast majority of patients,” Dr. Markman says.

“In the subset in whom these traditional therapies are ineffective, it is important for us to clarify exactly what the role of SBRT is, in whom it is effective, what patients are most likely to benefit and whether and how it can be done safely,” he adds. “This trial is critically important to get those answers.”

CAUTION: The RADIATE-VT study involves an investigational device. Limited by United States law to investigational use.

Referrals and consultations

To refer a patient for VT treatment, please call 877-937-7366, or refer a patient online. For questions about the RADIATE-VT trial, please contact Director of Clinical Research Wei Xu, MBE, at Wei.Xu@pennmedicine.upenn.edu.