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In the showdown between left atrial appendage (LAA) closure devices, the Amplatzer Amulet outperformed Watchman for peridevice leaks (PDL) in one trial longer term but not in another.

At 12 months of follow-up in the IDE trial that led to FDA approval of the Amulet occluder, fewer patients had moderate or worse PDL with it than did those with the Watchman device (10% vs 22%, P<0.001), reported Dhanunjaya Lakkireddy, MD, of HCA Midwest Health Heart and Vascular Institute in Kansas City, Kansas, at the Transcatheter Cardiovascular Therapeutics (TCT) meeting held in Orlando and broadcast online.

Small leaks of 3 mm or less by transesophageal echocardiography (TEE) were similar between groups, such that 10% fewer overall had any leak with Amulet. Those findings matched those reported previously at 45 days.

However, a smaller randomized trial also presented at TCT, and using cardiac CT angiography, suggested no such difference.

In it, the 45-day rate of justified crossover to another device during the implantation procedure or residual LAA patency detected was similar between Amulet and Watchman devices (67.6% vs 70.0%, RR 0.97, 95% CI 0.80-1.16), reported Roberto Galea, MD, of Bern University Hospital in Switzerland.

And unlike in the IDE study, Amulet had more major procedure-related complications than Watchman (9.0% vs 2.7%, P=0.047) in the SWISS-APERO trial, simultaneously published in .

A key difference between the trials was that the IDE trial largely looked at the Watchman 2.5 device, whereas SWISS-APERO included the Watchman FLX device now on the market.

"This is relevant for us as practicing clinicians because we have access to both of these devices," said TCT session panelist Robert Byrne, MB BCh, PhD, of RCSI University in Dublin. He called the "relatively high rate" of complications "striking" but questioned the use of a composite endpoint in SWISS-APERO.

CT imaging was the most accurate method for assessing patency, and having to switch between intended devices during the procedure could cause microtrauma to the heart that affects patients, Galea noted. The sole "justified" crossover over was a patient with a leaky Amulet device.

The higher rate of procedural complications in SWISS-APERO compared with IDE may have been due to the different definitions used, with Galea's group including events later than 7 days post-procedure and even minor and non-clinically relevant events.

Also, SWISS-APERO's population had higher baseline risk (almost 90% had a prior bleed versus less than 70% in the IDE trial) and inability to tolerate anticoagulation, whereas the IDE trial required patients to be eligible for short-term anticoagulation, Galea pointed out.

SWISS-APERO included 221 patients randomly assigned to Amulet or Watchman, which was a 2.5 device for the 23% enrolled before October 2019 and the FLX device for the rest. The IDE trial included 1,878 patients randomized to the Amulet or Watchman before the FLX device was released, with 1,291 followed up at 12 months. Both have follow-up planned for 5 years.

The clinical significance of peridevice leaks is still murky.

Galea pointed to an observational of more than 1,000 Watchman 2.5 patients, showing more thromboembolic events in those who developed residual leak. "It's still a target for [an] LAA operator to complete LAA sealing after the procedure," he concluded, although cautioning about the retrospective data.

Clinical outcomes were similar between device arms in both the IDE and SWISS-APERO trials.

"Indeed, we have to put these devices next to the DOACs [direct oral anticoagulants] to prove safety and efficacy toward avoiding these endpoints, because at the end that's what counts," said SWISS-APERO trial co-author Pascal Vranckx, MD, PhD, of Hasselt University in Hasselt, Belgium.

For now, Lakkireddy suggested that operator familiarity, anatomy, and ability to stay on anticoagulation for 45 days would be deciding factors in choosing between devices.