A first look at the implant success and sealing efficacy of a dual-seal left atrial appendage occlusion (LAAO) device that’s in development reveals successful implantation in 99.8% of people with atrial fibrillation in the VERITAS trial.

Early findings on the Amulet 360 device from Abbott showed that no participants experienced a primary safety event within 7 days of implantation or hospital discharge, whichever was later. Researchers across 34 sites worldwide reported no deaths, ischemic strokes, systemic emboli, or device- or procedure-related complications requiring open cardiac surgery or major endovascular intervention.

Of the 400 patients, 399 met the primary effectiveness endpoint: peri-device leakage (PDL) below 5 mm. On transesophageal echocardiography, two participants had a leak of 3 mm or less, and the remainder showed complete sealing. 

Investigators hope t his n ext-generation LAAO device will continue to demonstrate safety and efficacy without some of the concerns raised regarding the earlier Amplatzer Cardiac Plug version in the AMULET-IDE study. In that trial, the Amplatzer was linked to more frequent pericardial effusion and device embolization compared to the Watchman 2.5. 

“My take-home message is that the next-generation device can deliver excellent LAA (left atrial appendage) sealing with a very reassuring, early safety profile,” VERITAS lead author Devi Nair, MD, director of cardiac electrophysiology at St. Bernards Heart and Vascular Center in Jonesboro, Arkansas, told Medscape Medical News.

The study was published online on February 6 in JACC: Clinical Electrophysiology.

Clinical Questions Remain

At 45 days, 93.9% of participants had complete LAAO. This result compares favorably to a 63% complete closure with the previous version of the device in AMULET-IDE, Emile G. Daoud, MD, director of electrophysiology research at the Hatton Research Foundation at the Bethesda North Hospital in Cincinnati, wrote in an accompanying editorial comment. 

Forty-five days is an important early checkpoint, Nair said, but it’s not the end of the story. “It truly captures immediate procedural safety and early sealing,” he said. “But it’s definitely not sufficient to answer some of [the] clinical questions.” 

Remaining questions include the durability of closure, bleeding outcomes, and any long-term, device-related thrombus. Researchers will reassess participants in person at 12 months and by telephone at 6 and 24 months. 

When asked if any findings were unexpected, Nair said, “What stood out was the closure in the hands of multiple operators. For an LAAO population with variable anatomy, that degree of early closing consistency is very notable.”

In terms of safety, two patients experienced a pericardial effusion requiring draining: one on the day of implantation and a second at 44 days. Researchers also reported that a device-related thrombus occurred in nine patients, yielding a rate of 2.4%. 

The mean age of participants was 74 years, and 62% were men. The mean procedure time was 35 minutes.

Cautious Interpretation

“The procedural outcomes were exceptional,” Daoud wrote. “Impressively, no patient had a PDL exceeding 3 mm.” 

The VERITAS results represent “a meaningful improvement in the safety profile,” Daoud wrote, including a significant reduction in pericardial effusion requiring pericardiocentesis — 0.5% compared to 2.4% in the AMULET-IDE trial and 1.9% in EMERGE LAA.

Compared to the Amplatzer, the Amulet 360 features a recessed proximal end-screw, a broader size range, and additional retention anchors to enhance procedural success and safety.

Limitations included the single-arm study design, the generalizability of results, and the extent to which the device design can be credited for improved effectiveness, Daoud noted. For example, VERITAS included only highly experienced implanters, which could explain the high success of placement, low complication rate, and 35-minute procedure time.

Daoud also noted a “disturbing discrepancy” in device-related thrombus rates identified by the core laboratory — 2.4%, compared to 0.3% reported by operators on site. “This may reflect difficulty in detecting device-related thrombus, particularly sessile thrombi, along the device disc, and raises important questions about optimal surveillance strategies.”

Robert Helm, MD, a clinical cardiac electrophysiologist at Boston Medical Center in Boston, also raised the device-related thrombus issue. Helm was not involved in the study. 

“The frequency of device-related thrombosis on follow-up imaging is particularly concerning, especially given that all but one case was identified by the core laboratory rather than by the experienced site implanting physicians,” Helm told Medscape Medical News. 

“The results of the VERITAS trial should be interpreted cautiously,” Helm said. “At the surface, the study may appear favorable with high rates of implant success and appendage closure and no primary events within 7 days postprocedure, yet the procedure-related risks are not insignificant.” 

In addition to the experienced implanters, Helm noted the study population was highly selected, with more than 10% of enrolled patients excluded based on LAA anatomy or procedure-related criteria alone.

“Despite these measures, the 45-day rate of adverse clinical outcomes remained relatively high” at about 7%, he said. He cited the 2.4% device-related thrombus rate, 3.3% risk for major bleeding, 0.5% risk for pericardial effusion, and 0.5% risk for ischemic stroke or transient ischemic attack. 

“One patient experienced near-fatal, late cardiac tamponade, and two deaths — which were adjudicated as due to cancer — occurred within 45 days despite study entry criteria requiring anticipated life expectancy of greater than 2 years,” Helm added. “Its ultimate clinical value needs to be considered in the context of contemporary stroke-prevention strategies, including direct oral anticoagulation, and the emerging evidence that catheter ablation may reduce stroke risk.” 

Moving forward, Nair is focusing on durability, clinical outcomes including stroke, and identification of clinical subtypes that make for the best candidates. 

The study was funded by Abbott. Nair is a consultant for and received research grants from Boston Scientific, Abbott, Medtronic, Johnson & Johnson, Medtech, Atraverse, Siemens, and Volta. Helm reported serving as principal investigator in 2022-2023 and received research funding to his institution (Boston Medical Center) from Boston Scientific for research related to racial and ethnic inequities in outcomes and utilization of the Watchman LAAO device in a large, claims-based database. Daoud reported no relevant financial relationships.

Damian McNamara is a freelance contributor to Medscape Medical News. He worked full-time for Medscape and WebMD from 2018 to 2024. Damian has a BA in chemistry and an MA in science, health, and environmental reporting/journalism. He works out of a home office in Miami, with a 100-pound chocolate lab known to snore under his desk during work hours.