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PARIS -- Rates of major bleeding after left atrial appendage (LAA) closure tip the scales toward a less intense antithrombotic regimen after Watchman and Amplatzer Amulet implantation, researchers here suggested.

The Amulet Observational Study (including 1077 recipients of the Amplatzer Amulet LAA occluder across five continents) found that 7-90 days after receiving the implant, 4% of patients had major bleeds.

On the flip side, just 0.9% showed device thrombus within 90 days on transesophageal echocardiography (TEE), according to Ulf Landmesser, MD, of Switzerland's University Hospital, Zurich, during his presentation at EuroPCR.

At discharge, over half of patients were on DAPT (54.3%), with others receiving one antiplatelet (23.0%) and/or oral anticoagulation (18.9%).

This raises "the question of whether the anti-thrombotic regimen should be lowered to decrease the bleeding rate," Landmesser suggested.

Patients started with an average CHA₂DS₂-VASc and HAS-BLED score of 4.2 and 3.3 on average, respectively. At baseline, 82.8% were contraindicated to oral anticoagulation.

Placing the Amplatzer Amulet was associated with a periprocedural event rate of 3.2%, most events being major bleeding (2.4%) and major vascular complications (0.9%).

DAPT Subgroup of EWOLUTION

In another EuroPCR presentation, data from a second registry suggested that dual antiplatelet therapy (DAPT) could be terminated earlier than what is current practiced after LAA occlusion -- this time among recipients of the Watchman device.

From the all-comers EWOLUTION registry of Watchman recipients in Europe, investigators identified a DAPT subgroup that wasn't on oral anticoagulation (n=605).

Major bleeding occurred in 2.5% of this population within 1 year of Watchman implantation (with fatal bleeding at a rate of 0.5%), and device thrombus in 4.0%. One out of those 22 device thrombus cases was followed by stroke/TIA.

"Bleeding with DAPT was the most relevant serious adverse event," said Martin W. Bergmann, MD, of Cardiologicum Hamburg in Germany, adding that he suggested "alternatives to DAPT in oral anticoagulant-ineligible patients during the first 3 months."

Half of patients quit DAPT at 6 months, and three-quarters of the time they had switched to a single antiplatelet.

Overall, ischemic strokes were observed in 1.4%, Bergmann reported. Combined ischemic strokes, TIAs, and systemic embolisms raised that to 1.8%. There were no hemorrhagic or fatal strokes, however.

These patients went into the procedure with CHA₂DS₂-VASc score of 4.6 and HAS-BLED score of 2.4 on average. A contraindication to oral anticoagulation was reported for 83.8%

"Efficacy regarding stroke prevention in this high-risk, mostly oral anticoagulation-ineligible patient cohort was similar to randomized trials with oral anticoagulation-eligible patients," the authors concluded.

Warfarin Post-LAA Occlusion

"I strongly believe these studies. The large majority of patients who consent to undergo LAA closure do so because they have had problems with oral anticoagulation or because oral anticoagulants are contraindicated," said William O'Neill, MD, of Henry Ford Hospital in Detroit, in an interview with 番茄社区app.

"Unfortunately in the U.S., for market size reasons (driven by venture capitalists who bankrolled the original studies of Watchman), the Watchman trials happened in patients who were Coumadin [warfarin] eligible," he continued. "There is no scientific basis for use of Coumadin post-implant, but now it's written in the instructions for use and everyone is hesitant not to use Coumadin."

"I fervently hope that our practice can change so that Coumadin is not routinely used and that we can treat patients with high bleeding risk. Unfortunately, many patients are not being treated because clinicians believe they have too high a risk of bleeding for the 45 days they are required to be on Coumadin," added O'Neill who was not involved in the studies.

According to Vivek Reddy, MD, of Mount Sinai Hospital in New York City, the registries are practice-reinforcing.

"In general, device thrombus is a problem for all LAA closure devices. It is a manageable issue, but one that we would like to say in the less than 1% range," commented Reddy, who was not involved in the studies.

Importantly, the Amplatzer Amulet was previously associated with a colossal 16.7% rate of device thrombosis at 3 months among European operators.