SAN FRANCISCO — A focused form of radiation akin to that used to destroy solid tumors may be effective at controlling high-risk ventricular arrhythmias in patients who failed to respond to an initial round of ablation, a new study suggests.

The small, retrospective analysis found stereotactic arrhythmia radiotherapy (STAR) appeared to be no worse than repeat catheter ablation at controlling refractory ventricular tachycardia (VT), according to the researchers, who presented their results at the 2025 annual meeting of the American Society for Radiation Oncology. The study also appeared in the International Journal of Radiation Oncology Biology Physics.

“Our study found that for patients with high-risk refractory ventricular tachycardia — in other words, patients who haven’t responded to traditional therapies and are at high risk for complications — treatment with STAR resulted in equivalent efficacy, meaning cardiac control, and a better safety profile, compared to repeat catheter ablation,” Shannon Jiang, MD, a radiation oncology resident at Washington University School of Medicine in St Louis, told Medscape Medical News.

Although the findings did not reach statistical significance, “I think our research adds legitimacy to the approach and underscores its potential as an option for patients, especially those at high risk for complications from anesthesia or ablation,” Jiang said in a news release.

Medically Fragile Patients

Typical management of VT involves the use of antiarrhythmic medications, followed by placement of a cardiac device, and then catheter ablation. However, many patients with high-risk refractory VT don’t respond to these standard treatments, Jiang said. T hese patients, whom she described as “medically fragile,” are challenging to treat because they are vulnerable to complications when subjected to an invasive procedure, such as ablation.

A previous trial (ENCORE-VT) found cardiac radiation was associated with “markedly reduced” VT and use of anti-arrhythmic drugs and improved quality of life. STAR has also been associated with decreased frequency of implantable cardioverter defibrillator shocks.

For the new study, Jiang and colleagues retrospectively analyzed data drawn from the medical records of 43 patients with high-risk refractory VT. Most (90%) had already undergone at least one ablation procedure. The remaining 10% were regarded as “medically unfit” for ablation.

Patients received STAR (n = 22) or standard repeat catheter ablation (n = 21). All the patients had similar baseline demographics (91% men; median New York Heart Association [NYHA] class III; median left ventricular ejection fraction, 25%), but patients who received STAR were generally older and had high-risk International VT scores and higher pulmonary disease, ischemic cardiomyopathy, age, NYHA functional class, ejection fraction, storm, diabetes mellitus scores.

Patients were followed for 3 years, with a 6-week blanking period. Outcomes included serious treatment-related adverse events, overall survival, and freedom from death, shock, or storm.

Of the patients who received STAR, 91% (n = 20) survived the blanking period compared with only 76% (n = 16) of the patients who received ablation.

Median time of freedom from death, shock, or storm were similar between the groups but appeared to favor STAR vs ablation at the first year.

At 1 year, serious adverse events related to treatment were more frequent in patients who received ablation than those who received STAR, and with an almost 9-month difference in the median time to any such episode.

Twelve patients who received STAR died within the 3-year period, nine from causes unrelated to their arrhythmia and none from an adverse event associated with treatment, according to the researchers.

Median overall survival appeared to be superior in patients who received STAR than those who received ablation, with STAR continuing to show some superiority at the 1- and 2- year marks. At 3 years, the difference leveled out at 45% for both groups.

“The main advantage of STAR seems to be its safer posttreatment period compared to catheter ablation,” Jiang said. “Additionally, treatment efficacy was equivalent for STAR and catheter ablation.”

The study was limited by its small size and retrospective design, Jiang said. A multi-center randomized controlled trial to evaluate the safety and efficacy of STAR relative to ablation (RADIATE-VT) is currently enrolling patients.

Promising but Preliminary

Konstantinos Aronis, MD, PhD, director of the Adult Congenital Heart Disease Complex Ablation Program and associate director of the Ventricular Tachycardia Ablation Program at Johns Hopkins School of Medicine in Baltimore said the new data on STAR are “going in the right direction to suggest this is a promising therapy.”

“The current study included only 43 patients, and the P values didn’t reach statistical significance.” In addition, because the study wasn’t randomized, it might have included selection bias.

Aronis wondered whether 3 years is a sufficient amount of time to monitor for potential complications. “If you have a complication from a conventional ablation, you find out within the first hours or weeks, not years later. But we know from other instances where stereotactic radiation is used, such as breast or lung cancer, that we see side effects many more years down the road — in the 10-year horizon, or so,” he said.

“I hope to see randomized studies proving that it’s equivalent, safer, and quicker and also to see guidance on how to select patients who would do well with this vs conventional ablation,” he said.

‘Bridge to Transplant?’

Kenneth Rosenzweig, MD, chair of the scientific committee for the meeting said ablation will “always be the primary treatment for patients with ventricular tachycardia.”

The question is whether STAR might play a role in helping certain patients where ablation is no longer working and must be repeated multiple times with diminishing benefit, said Rosenzweig, professor and chair of the Department of Radiation Oncology at the Icahn School of Medicine at Mount Sinai, New York City.

He shared the story of a patient with refractory VT who was treated with radiation. “A few days later, he was able to be discharged. He attended his daughter’s wedding 3 weeks later, walked her down the aisle, and then, 6 months later, got a heart transplant.” A potential role for radiation therapy might thus be a “bridge to transplant” in some of these patients, Rosenzweig added.

This study received no funding. Jiang and Rosenzweig reported no relevant financial conflicts of interest. Aronis reported receiving honoraria from Johnson and Johnson for educational presentations to trainees.

Batya Swift Yasgur, MA, LSW, is a freelance writer with a counseling practice in Teaneck, New Jersey. She is a regular contributor to numerous medical publications, including Medscape and WebMD, and is the author of several consumer-oriented health books as well as Behind the Burqa: Our Lives in Afghanistan and How We Escaped to Freedom (the memoir of two brave Afghan sisters who told her their story).