Second-gen Watchman leads to LAA closure success with few adverse events

Left atrial appendage (LAA) closure with the new-generation WATCHMAN FLX device has met both the primary safety and efficacy endpoints in a US FDA Investigational Device Exemption clinical study (PINNACLE FLX trial), resulting in high procedural success with few incidences of safety events.

In a cohort of nonvalvular atrial fibrillation (NVAF) patients with indication for oral anticoagulation (OAC), LAA closure (defined as peridevice flow ≤5 mm on transesophageal echocardiography [TEE]) rate at 1 year was 100 percent, according to the investigators. [Circulation 2021;doi:10.1161/CIRCULATIONAHA.120.050117]

There were two cases of periprocedural stroke (0.5 percent) that occurred within 7 days after the procedure or by hospital discharge, with both patients making a good recovery. One stroke occurred a day after an unsuccessful procedure and led to a new visual-field deficit, while the other occurred 2 days after a successful procedure and led to minimal residual symptoms at discharge.

The safety events seemed unrelated to the device, the investigators noted, “as in the first case no device was placed, and in the second case, the likely cause was due to severe intracranial atherosclerotic disease.”

Seven patients had device-related thrombus, but none experienced pericardial effusion requiring open cardiac surgery. “Importantly, there were no early or late embolizations of this next generation LAA closure device in this study,” the investigators added.

Adjudicated clinical outcomes at 1 year included all-cause death (6.6 percent), cardiovascular/unknown death (4.4 percent), and ischaemic stroke (2.6 percent). Four patients (1.0 percent) had pericardial effusions, all of whom required pericardiocentesis or pericardial puncture. Major bleeding (BARC 3 or 5) was documented in 7.9 percent.

PINNACLE FLX included a total of 400 NVAF patients (mean age 73.8 years, 35.5 percent female, mean CHA2DS2-VASc score 4.2). The implant was successfully delivered and released into the LAA in 395 patients (98.8 percent). Three of the five failed attempts were due to unsuitable anatomy, while the other two were attributed to adequate compression and/or inadequate seal.

The antithrombotic regimen postprocedure involved a direct (D)OAC (apixaban 76.7 percent, rivaroxaban 20.3 percent) plus aspirin for 45 days, followed by clopidogrel plus aspirin over 6 months, and then aspirin for an indefinite period.

New and improved WATCHMAN

Mechanical closure of the appendage has emerged as a minimally invasive therapeutic option to prevent thrombus embolization from the LAA in patients with NVAF. “This is intended to help patients … [wean off] lifelong anticoagulant therapy for stroke prevention,” according to the investigators.

Several clinical trials and observational studies have established the safety and clinical effectiveness of the first-generation WATCHMAN device for risk reduction of AF-related embolic strokes in patients at high risk. However, investigators acknowledged that the device had inadequacies in terms of size matrix, ability to fully recapture the device, risk of perforation, device-related thrombus (DRT) formation, and peri-device leak. [Lancet 2009;374:534-542; J Am Coll Cardiol 2014;64:1-12; J Am Coll Cardiol 2019;74:2878-2889]

The second-generation WATCHMAN was designed to address its predecessor’s limitations as well as to expand the eligible patient population. It is still available in five sizes but covers a slightly larger range of LAA diameters—from 14–1.5 mm—to accommodate a wider variety of anatomies. The device also features an atraumatic closed distal end to lower the risk of perforation, dual-row anchors to minimize the likelihood of embolization, and reduced metal exposure.

In conclusion, the investigators stated that the WATCHMAN FLX could indeed minimize the risk of the major complications of LAA closure, as evidenced by successful device implantation without prohibitive safety issues and effective appendage closure upon TEE imaging at 1 year.