PARIS – The Amplatzer Amulet left atrial appendage occlusion device reduced stroke risk by nearly 60% at 1 year in a large, real-world registry of patients with atrial fibrillation at dual high risk for stroke and bleeding, Ulf Landmesser, MD, reported at the annual meeting of the European Association of Percutaneous Cardiovascular Interventions.
One of the most impressive findings was that this feat was accomplished by and large without background oral anticoagulation. Indeed, 83% of the 1,088 patients in this 61-center, 17-country study had contraindications to oral anticoagulation. Only 11% of subjects were discharged on oral anticoagulation after device implantation, while 22.5% were discharged on aspirin or clopidogrel monotherapy. By 1-3 months post implantation, 60% of patients were either on a single antiplatelet agent or no antithrombotic medication at all.
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Dr. Ulf Landmesser
“Antithrombotic therapy was individualized by the patient’s physician. There didn’t seem to be an increased risk of device-related thrombus in these patients on single antiplatelet therapy. Our data suggest that, given the high bleeding risk, single antiplatelet therapy seems to be a good option for these patients,” said Dr. Landmesser, a professor in and the chair of the department of cardiology at Charité Medical School in Berlin.
Participants in the Global Prospective Amulet Study averaged 75 years of age, and 72% had a history of major bleeding. The average CHA2DS2-VASc score was 4.2, with a HAS-BLED score of 3.3, which emphasizes the high-risk nature of study participants.
On the basis of the CHA2DS2-VASc score, the predicted 1-year ischemic stroke rate without oral anticoagulation was 6.7%, so the actual 2.9% rate represented a 57% reduction in risk. Similarly, for the composite endpoint of ischemic stroke, transient ischemic attack, or systemic embolism, the predicted rate was 9.4%, but the achieved rate was 3.8%, which represented a 60% reduction in risk.
The annualized major bleeding rate was 10.3% despite the low usage of oral anticoagulation or dual-antiplatelet therapy. However, the rate of procedure- or device-related major bleeding was only 3.2%; the other 7.1% was unrelated to Amulet and reflected the underlying high risk of the study population.
The 1-year mortality rate was 8.4%. Thirty-five deaths had cardiovascular causes, 35 were noncardiovascular, and in 18 patients, cause of death couldn’t be determined.
The device-related thrombus rate through 1 year was 1.7%; 10 of 18 cases occurred within the first 90 days.
Dr. Landmesser emphasized that this was a particularly rigorously conducted registry. A unique feature was its use of an independent echocardiography core lab to assess procedural success, as well as an independent clinical events committee to adjudicate serious adverse events. Prior studies of other left atrial appendage (LAA) occlusion devices didn’t use these measures.
The Amplatzer Amulet is a second-generation occlusion device designed for easier placement and more complete sealing than its predecessor and comes in eight sizes to address anatomic variations. At implantation, adequate LAA occlusion as defined by the echocardiography core laboratory was achieved in 99.3% of patients; at that time, 89.4% of patients had no residual flow, and another 9.9% had a residual flow of less than 3 mm. At 1-3 months of follow-up, echocardiography showed 98.4% of patients had adequate occlusion.
Session cochair Alberto Cremonesi, MD, pronounced this to be “really important data.”
“I want to stress that these device implantations were transesophageal echocardiography–guided. In my mind this is absolutely essential to your excellent long-term results,” observed Dr. Cremonesi of Maria Cecilia Hospital in Cotignola, Italy.
Asked to speculate on what outcomes might have looked like had patients been treated with an oral anticoagulant rather than the Amulet occlusion device, Dr. Landmesser predicted the major bleeding rate would have been substantially higher than 10.3%. Most of the bleeding events in the study were gastrointestinal, and the novel oral anticoagulants are known to boost the risk of GI bleeding.
But that’s speculation. He noted that two ongoing randomized trials – one in Germany, the other in Scandinavia – are randomizing high-risk patients to a LAA occlusion device or best medical care, including a novel oral anticoagulant when not contraindicated. The Scandinavian study uses the Amulet, while the German trial uses both the Amulet and the Watchman device. The primary endpoint is the ischemic stroke rate.
The Amulet registry, which will continue for a second year of follow-up, was sponsored by Abbott Laboratories, which developed the Amulet device. Dr. Landmesser reported serving as a consultant to Abbott, as well as Biotronik, Rewa, and Bayer.