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SAN FRANCISCO -- Cardioneural ablation helped some people with vasovagal syncope reduce their burden of fainting spells with few procedural complications, according to initial experience so far in the U.S.

With this novel catheter-based ablation procedure, operators sought to achieve vagal denervation in people with autonomic bradycardia and/or neurocardiogenic syncope. Radiofrequency (RF) application elicited a parasympathetic response in 59% of compassionate-use patients, and a sympathetic response in 70%, reported Roderick Tung, MD, of the University of Arizona College of Medicine-Phoenix.

During the procedure, RR intervals shortened from 1047 ms to 775 ms (P<0.001); there were also non-significant decreases in AH interval (from 102 ms to 95 ms) and HV interval (46 to 44 ms), Tung reported at the Heart Rhythm Society (HRS) annual meeting.

Notably, 82% of patients were free from syncope at a median 8.5 months after a single procedure. Five people out of 71 needed a repeat ablation by then.

Cardioneural ablation may therefore be an attractive alternative to implanting a permanent pacemaker in young people with vasovagal syncope.

"The benefits of ablation for patients with arrhythmias is well-established, and now we have the potential to apply this modified approach to a young patient population in desperate need of a solution. Some patients included had significant head and facial trauma as a result of their sudden fainting episodes," Tung said in a press release. "We believe our findings lay the groundwork for new indications for CNA [cardioneural ablation], after seeing the significant impact ablation can make in rebalancing the autonomic nervous system."

HRS session discussant Dhanunjaya Lakkireddy, MD, of the Kansas City Heart Rhythm Institute at HCA Midwest Health, Missouri, called this "an area of extreme interest" as researchers have not come up with any new therapies for these patients in the last 3 decades.

CNA was first developed in Brazil in 2004. Subsequent reports have shown promising results for the relief of autonomically-mediated bradycardia using this technique, which utilizes the same electrophysiology tools for atrial fibrillation (Afib) ablation.

"It's more about where to burn, how much to burn, and when you're done that we still need to answer in this field," Tung said during an HRS press conference.

His group's retrospective study was based on a multicenter registry of compassionate off-label CNAs. The procedures had been performed from 2016 to 2022 at 13 U.S. centers.

Patients were 71 adults who had not responded to medical therapy and/or behavioral modification. They ranged from ages 30 to 64 (mean age 47), and were roughly split between the sexes.

People had a mix of sinus bradycardia (66%), vasovagal syncope (30%), and AV block (4%). This was based on ambulatory monitoring (63%), implantable loop recordings (26%), and tilt-table tests (11%).

Tung's group tested various ganglionated plexi (GP), where the nervous system plugs into the heart, as ablation targets. Average RF duration was 612 seconds. Procedural complications were one tamponade and two junctional rhythms.

The lack of uniformity in diagnosis and ablation approach was a major study limitation.

Indeed, the report was a "mish-mash of many things that many people do differently," according to Lakkireddy. He cautioned that 63% of CNA cases were adjunctive procedures during concomitant primary ablation (largely for Afib/atrial flutter ablation), which makes it "hard to tease what lesion did what," he said.

Finally, the duration of cardioneural ablation's therapeutic effect is unknown, given the limited follow-up. However, some data from Brazil suggest it can last 5 years, Tung noted.

"I think we're still learning, so it's hard to say that someone has it all down. But that's why this is really exciting, it's a new field," he said.

The investigator suggested that researchers take on prospective registries and comparative studies on procedural endpoints and GP localization. Bringing CNA to multicenter, sham-controlled trials "would be a dream," he said.

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