PARIS – Percutaneous left atrial appendage closure with an Amplatzer device in patients with nonvalvular atrial fibrillation was associated with significantly lower rates of all-cause and cardiovascular mortality, compared with oral anticoagulation, in a large propensity score–matched observational registry study.
Left atrial appendage closure (LAAC) also bested oral anticoagulation (OAC) with warfarin or a novel oral anticoagulant (NOAC) in terms of net clinical benefit on the basis of the device therapy’s greater protection against stroke and systemic embolism coupled with a trend, albeit not statistically significant, for fewer bleeding events, Steffen Gloekler, MD, reported at the annual congress of the European Association of Percutaneous Cardiovascular Interventions.
The Watchman LAAC device, commercially available both in Europe and the United States, has previously been shown to be superior to OAC in terms of efficacy and noninferior regarding safety. But there have been no randomized trials of an Amplatzer device versus OAC. This lack of data was the impetus for Dr. Gloekler and his coinvestigators to create a meticulously propensity-matched observational registry.
Five hundred consecutive patients with AF who received an Amplatzer Cardiac Plug or its second-generation version, the Amplatzer Amulet, during 2009-2014 were tightly matched to an equal number of AF patients on OAC based on age, sex, body mass index, left ventricular ejection fraction, renal function, coronary artery disease status, hemoglobin level, CHA2DS2-VASc score, and HAS-BLED score. During a mean 2.7 years, or 2,645 patient-years, of follow-up, the composite primary efficacy endpoint, composed of stroke, systemic embolism, and cardiovascular or unexplained death occurred in 5.6% of the LAAC group, compared with 7.8% of controls in the OAC arm, for a statistically significant 30% relative risk reduction. Disabling stroke occurred in 0.7% of Amplatzer patients versus 1.5% of controls. The ischemic stroke rate was 1.5% in the device therapy group and 2% in the OAC arm.
All-cause mortality occurred in 8.3% of Amplatzer patients and 11.6% of the OAC group, for a 28% relative risk reduction. The cardiovascular death rate was 4% in the Amplatzer group, compared with 6.5% of controls, for a 36% risk reduction.
The composite safety endpoint, comprising all major procedural adverse events and major or life-threatening bleeding during follow-up, occurred in 3.6% of the Amplatzer group and 4.6% of the OAC group, for a 20% relative risk reduction that is not significant at this point because of the low number of events. Major, life-threatening, or fatal bleeding occurred in 2% of Amplatzer recipients versus 5.5% of controls, added Dr. Gloekler of University Hospital in Bern, Switzerland.
The net clinical benefit, a composite of death, bleeding, or stroke, occurred in 8.1% of the Amplatzer group, compared with 10.9% of controls, for a significant 24% reduction in relative risk in favor of device therapy.
Of note, at 2.7 years of follow-up only 55% of the OAC group were still taking an anticoagulant: 38% of the original 500 patients were on warfarin, and 17% were taking a NOAC. At that point, 8% of the Amplatzer group were on any anticoagulation therapy.
Discussion of the study focused on that low rate of medication adherence in the OAC arm. Dr. Gloekler’s response was that, after looking at the literature, he was no longer surprised by the finding that only 55% of the control group were on OAC at follow-up.
“If you look in the literature, that’s exactly the real-world adherence for OACs. Even in all four certification trials for the NOACs, the rate of discontinuation was 30% after 2 years – and these were controlled studies. Ours was observational, and it depicts a good deal of the problem with any OAC in my eyes,” Dr. Gloekler said.
Patients on warfarin in the real-world Amplatzer registry study spent on average a mere 30% of time in the therapeutic international normalized ratio range of 2-3.
“That means 70% of the time patients are higher and have an increased bleeding risk or they are lower and don’t have adequate stroke protection,” he noted.
This prompted one observer to comment, “We either have to do a better job in our clinics with OAC or we have to occlude more appendages.”
A large pivotal U.S. trial aimed at winning FDA approval for the Amplatzer Amulet for LAAC is underway. Patients with AF are being randomized to the approved Watchman or investigational Amulet at roughly 100 U.S. and 50 foreign sites.
Dr. Gloekler reported receiving research funds for the registry from the Swiss Heart Foundation and Abbott.
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