Left atrial appendage occlusion (LAAO) using the Amplatzer Amulet (Abbott) device has a high implant success rate and a low procedural complication rate in a population at high risk of stroke and major bleeding, one-year outcomes from a roll-in cohort of the Amulet investigational device exemption (IDE) trial, have shown. The findings were presented by Stephan Windecker (Bern University Hospital, Bern, Switzerland) during a late breaking trial session at PCR e-Course 2020 (25-27 June).
The Amplatzer Amulet device, Windecker explained, is implanted by transfemoral venous access and transseptal puncture into the left atrial appendage to prevent systemic embolism in patients with atrial fibrillation (AF). The device consists of a lobe that is positioned inside the left atrial appendage neck and is anchored by stabilising wires, with a disc designed to seal the orifice.
The safety and efficacy of the device are currently being examined in the Amulet IDE trial, a prospective, global, multicentre, non-inferiority trial with 1:1 randomisation, comparing Amplatzer Amulet to the Watchman device (Boston Scientific). Windecker noted that, although many physicians involved in the trial had experience of using the Watchman device, “US implanting physicians did not have Amulet implant experience in this trial”.
In total, the study includes 1,878 patients enrolled at 108 sites; however, the results presented by Windecker focused on the pre-specified cohort of 201 roll-in patients enrolled at 82 sites within the USA, with one-year follow-up.
The primary study outcomes of the roll-in phase of the trial comprised 45-day closure rate, procedure-related complications, all-cause mortality, and major bleeding through one year, as well as ischaemic stroke and systemic embolism within one year, while secondary outcomes included implant success and device related thrombus.
The study cohort was characterised by Windecker as being an elderly patient population with a mean age of 74 years, predominantly male (61.7%), and with a slightly reduced left ventricular ejection fraction of 55%. They had a high risk of stroke, as indicated by a CHA2DS2-VASc score of 4.6, and an increased risk of bleeding, with a HAS-BLED score of 3.3; 43.3% of patients had previously been treated with warfarin, and 30.3% with novel anticoagulants (NOACs).
Of the 201 patients enrolled, 198 completed the 45-day follow-up visit, and 194 patients completed transoesophageal echocardiography (TEE) at 45 days. Complete follow up at 12 months was available for 185 patients.
The mechanism of action endpoint, characterised by peri device leak of ≤5mm at 45 days, was observed in 98.9% of patients, Windecker said, adding that the primary safety endpoint at one year, a composite of procedural complications, all-cause death, and major bleeding, was observed in 18.4% of patients.
Procedural complications occurred in 3.5%, he added, with device embolisation in one patient, pericardial effusion or tamponade in three patients, vascular complications in two patients and haematuria in one patient. The rate of all-cause mortality was 4.5% and major bleeding was 3.5% during the procedural period, and 11.9% during the non-procedural period, throughout one year. Neurological events throughout one year were observed in 2% of patients, consisting of ischaemic stroke and no suspended embolism. Secondary outcomes included implant success in 99% of patients, and device related thrombus as assessed at 45 days in 3.1% of patients.
In conclusion, Windecker said: “Despite the limited experience of the operators participating in the Amulet IDE roll-in phase, there was a low rate of procedural complications, in 3.5% of patients, and a high rate of implant success, in 99% of patients.
“Therefore, it can be concluded that LAA occlusion using the Amplatzer Amulet device has a high implant success rate and a low procedural complication rate in a population with high risk of stroke and bleeding. It provides a sound basis for the main Amulet IDE outcome trial.