Superiority Abbott needed, and superiority Abbott got. Full data from the head-to-head trial comparing Abbott’s Amplatzer Amulet left atrial appendage occluder versus the established product in this space, Boston Scientific’s Watchman, put Amulet ahead – though only on one of the trial’s primary endpoints. The results, presented yesterday at the European Society for Cardiology meeting, show Amulet’s noninferiority to Watchman across four endpoints, but its superiority on just one: the rate of successful LAA closure at 45 days. Amulet was approved mid-month for use in atrial fibrillation patients at increased risk of stroke on the strength of these data. And Amulet will be better able to treat patients at high risk of bleeding, since only 20% of recipients required anticoagulant therapy, versus 82% on Watchman. But there is a reason for caution: the comparator was an earlier version of Watchman that Boston has now phased out, so doctors have no definitive data on how Abbott’s newly available device compares against Watchman FLX, the version currently on the market. A cross-trial comparison might give a hint. On the measure of complete LAA closure Amulet achieved 60% versus Watchman’s 46%, but in a separate study Watchman FLX managed 90%.
|Amulet trial data|
|Outcome||N (%)||P value for noninferiority||P value for superiority|
|Primary mechanistic endpoint* at 45 days||792 (98.9)||767 (96.8)||<0.001||0.003|
|Primary safety endpoint** at 12mth||131 (14.5)||130 (14.7)||<0.001||0.47|
|Primary effectiveness endpoint† at 18mth||25 (2.8)||24 (2.8)||<0.001||0.5|
|Stroke, systemic embolism, CV or unexplained death at 18mth||50 (5.6)||67 (7.7)||<0.001||0.09|
|*Successful LAA occlusion (residual jet around the device ≤5mm); **composite of procedure-related complications, all-cause death, or major bleeding; †composite of ischaemic stroke or systemic embolism. Source: ESC 2021 & Circulation.|