麻豆传媒

SAN FRANCISCO -- Stroke prophylaxis with a novel permanent filter implanted in the carotid arteries is feasible for high risk atrial fibrillation (Afib) patients, a pilot trial showed.

Placing the Vine coil filter, which unfurls into the artery from a motorized unit placed through direct transcutaneous carotid puncture under ultrasound guidance, was a technical success in 92% (proper placement in both carotids and no major device- or procedure-related adverse event).

The device caught emboli in four of the 25 patients, and these were dissolved with subcutaneous heparin and no symptoms, reported Vivek Reddy, MD, of Icahn School of Medicine at Mount Sinai in New York City, and colleagues at the Heart Rhythm Society (HRS) meeting and online in the .

No major adverse events occurred related to the device or procedure, although there were minor puncture site hematomas or swelling in 20%.

"During an average follow-up of 6 months, there was no evidence of in situ thrombus formation or CCA [common carotid artery] stenosis," the researchers wrote. "Preventing stroke is arguably the most important clinical management goal in the treatment of atrial fibrillation."

Developing more treatment options for the growing Afib population unable to take anticoagulants is an important goal, commented HRS session moderator Jodie Hurwitz, MD, of the North Texas Heart Center in Dallas.

"As our patients live longer, especially our atrial fibrillation patients, they have increased risk for anticoagulation -- either marked anemia, bleeding, frequent falls," she told 麻豆传媒. "It would be nice to have something safe that we can protect them."

While the small study was not powered or designed to assess clinical outcome impact, a single patient had two minor strokes in territories of the brain not fed by the carotids and adjudicated as device-unrelated.

While the anterior circulation is felt to be the most common area for these strokes, the device is "only able address emboli of a certain size," Hurwitz noted. "Hopefully anything that is smaller would not cause significant CVAs [cerebrovascular accidents] and strokes."

The CAPTURE trial included 25 patients with atrial fibrillation and a CHA₂DS₂-VASc of at least 2 (average 4.4), who were "unsuitable" for oral anticoagulants. Participants also had to have a common carotid artery diameter in the target range of 4.8 to 9.8 mm and no carotid stenosis >30%.

Nearly half of the patients had a prior stroke or other embolism (48%), and 12% had multiple prior strokes. Patients received dual antiplatelet therapy for 3 months, then aspirin alone.

The filter is made of super-elastic nitinol wire with a circular cross-section that unfolds into a helix with supporting coils, a cone-shaped filter, and a linear stem across the carotid artery wall and internal and external anchors.

There were nine failures to implant the device due to size of vessel unsuitable to the device and poor visibility of the CCA and needle in patients whose carotids were >4 cm below the skin. The implant was retracted immediately and another properly-sized filter successfully placed for seven of the nine patients.

The placement failures were one case in which plaque missed on screening ultrasound blocked placement on one side, and an unsuccessful procedure attempt in a second patient due to "poor ultrasonic visibility."

All devices properly positioned at the end of the procedure stayed that way at all subsequent follow-ups.

However, Hurwitz cautioned that it's a limited number of patients and only 6 months of follow-up. "Really, we're looking at what the randomized trials are, because we've all seen stuff that we think looks great, then we discover, when there are randomized trials, that things are not exactly what we thought they would be."

Reddy acknowledged that nitinol filters placed in the inferior vena cava (IVC) have had fracture and migration problems, but he suggested some differences in anatomy and device design may help prevent such issues in this case.

"Unlike say IVC filters, this particular coil is placed through the wall. We're puncturing through the carotid artery. What's left is this coil that is within the artery, but then there's part of the coil that sticks through the arterial wall. So the expectation is that would help prevent migration."

The good news is, that if it does fracture, it would likely be stopped by the bifurcation of the artery about 1 cm beyond it, he added. "The reality is we don't know. We need to follow these patients out, as well as a lot more patients," he said.

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