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Pulsed field ablation continues to look promising for atrial fibrillation in early results, researchers reported in two studies at the .

A 14-patient prospective pilot study of pulsed field ablation, which uses less than 1-second pulses of electricity to kill tissue by damaging cell membranes (electroporation), showed acute isolation of all 56 pulmonary veins treated, as demonstrated by entrance block.

There weren't any device- or procedure-related serious adverse events by 30 days with the novel PulseSelect ablation device, reported Atul Verma, MD, of Southlake Regional Health Center in Toronto. There was one serious case of groin bleeding, deemed unrelated to the device used.

Notably, there were no cases of esophageal injury or phrenic nerve injury. The maximum esophageal temperature measured was 36.1°C, with an average 0.06°C change.

"We feel that irreversible electroporation, or pulsed field ablation, is going to be able to accomplish ablation of myocardial cells while sparing the collateral damage of some of these other cells," Verma said at an HRS press conference. "It's potentially going to be much safer ... I think we are also going to see that it's far more efficient and faster for the operator as well."

A second first-in-human trial of pulsed field ablation was presented at the same session, this time adding the option of additional radiofrequency ablation.

The study used a novel lattice-tip radiofrequency (RF) ablation catheter designed for a large "thermal footprint" that could also toggle to deliver pulsed field ablation.

Among 55 paroxysmal atrial fibrillation patients and 21 with persistent atrial fibrillation treated at three European centers, 40 received a combination of RF anteriorly and pulsed field ablation for the posterior lesions while the rest got only pulsed field ablation for both areas.

The procedures were acutely successful in 100% of cases, reported Vivek Reddy, MD, of the Icahn School of Medicine at Mount Sinai in New York City.

None of the patients had pulmonary vein stenosis at 3 months, although there was a case (1.3% rate) of major vascular complication: a vascular pseudoaneurysm that required surgical repair. "Interestingly, that was on the contralateral side where the puncture is for the ablation catheter," he said at the HRS press conference.

Minor complications included four patients with vascular injury, none requiring surgical repair.

Brain magnetic resonance imaging in a subset of 51 patients came up diffusion-weighted imaging (DWI) positive but fluid-attenuated inversion recovery (FLAIR) negative in 9.8% of patients and DWI and FLAIR positive in 5.9%.

Esophageal endoscopy in 60 patients showed minor erythema in 3.3%, all in patients who got RF as part of their procedure.

"I can easily imagine in a few years or 10 years, whatever it is, as we learn more about PF [pulsed field] biophysics and lesion formation that we may move toward a pure PF strategy," Reddy said.

"But I think it's not a foregone conclusion that will happen. It took decades for us to understand what we know about RF, and it continues to evolve. It's ludicrous to think we know everything about PF and can accept its safety and efficacy," he added.

Verma was more optimistic, although agreeing that it might not be a blanket solution.

"Collateral damage is something we are particularly worried about in the left atrium and left atrial tissues are thin enough that we can certainly get transmural lesions very, very easily with pulsed field ablation," he said. "I believe we can move toward a pulsed field-only strategy particularly for the left atrium, and probably for that matter most parts of the right atrium."

"Where there's a little bit more of an unknown is ventricular tissue," he added. "With the thickness of ventricular tissue can we get the depth we need from pulsed field ablation? How will pulsed field ablation stack up against radiofrequency? There are a lot of questions still to be answered there."

Verma called for long-term outcome data and larger pivotal studies. His group has a awaiting the greenlight by the FDA, although are possible.