Next-gen WATCHMAN-FLX device overcomes limitations of conventional devices: the PINNACLE study.

Left atrial appendage (LAA) occlusion provides an alternative to oral anticoagulation (OAC) for thromboembolic risk reduction in patients with non-valvular atrial fibrillation (NVAF). Since regulatory approval in 2015, the WATCHMAN device has been available for clinical use. In this month's issue of Circulation Journal, the results from PINNACLE FLX study have shown that a next-generation LAA closure device, the WATCHMAN-FLX in NVAF patients was successful without prohibitive safety issues, and displayed effective appendage closure upon echo imaging at 12 months.

Transcatheter LAA closure has emerged as a minimally invasive therapeutic option to prevent thrombus embolization from the LAA in patients with NVAF. While the first generation device is associated with a relatively low procedure-related complication incidence of 2.2, there are still some limitations of the device with regards to the size matrix, ability to fully recapture the device, risk of perforation, device-related thrombus (DRT) formation, and peri-device leak. 

The Protection against Embolism for non-valvular AF Patients: Investigational Device Evaluation of the Watchman FLX LAA Closure Technology (PINNACLE FLX) study was a prospective, non-randomized, multi-center FDA study. The primary safety endpoint was the occurrence of one of the following events within 7 days post-procedure or by hospital discharge, whichever was later: death, ischemic stroke, systemic embolism, or device- or procedure-related events requiring cardiac surgery. The primary effectiveness endpoint was the incidence of effective LAA closure (peri-device flow ≤5mm), as assessed by the echocardiography core laboratory at 12-month follow-up.

A total of 400 patients were enrolled with a mean CHA2DS2-VASc score was 4.2±1.5. The incidence of the primary safety endpoint was 0.5% meeting the performance goal (PG) of 4.2%. The incidence of the primary effectiveness endpoint was 100%, device-related thrombus was reported in 7 patients, no patients experienced pericardial effusion requiring open cardiac surgery, and there were no device embolizations.

The next generation LAA closure device was developed with following design improvements to mitigate the complications:

1. Self-expanding nitinol frame with 18 peripheral fixation anchors (2 rows of 9) and a permeable polyester fabric covering the atrial facing surface.

2. The new device is available in 5 sizes, accommodating a wider variety of anatomies.

3. The atraumatic closed distal end was designed to reduce the risk for perforation, along with two rows of J-shaped fixation anchors to provide control and stability of deployment, and the ability for full and partial recapture and redeployment.

4. The 18- rather than 10- strut design along with an open architecture configuration allows the device to conform to the LAA ostium and reduce peri-device leak. The threaded insert in the center of the proximal face is recessed, decreasing the amount of exposed metal volume to potentially improve healing and decrease device-related thrombus.(Figure)

Pericardial effusion is the most common serious procedure-related complication and varies from 0.4-4% with contemporary devices. In the present study, there were no pericardial effusions requiring drainage in the first 7 days.

Device embolization rates using current devices varies around 0.2 to 2%. There were no early or late embolizations of this next generation LAA closure device in this study. The decreased height, presence of two rows of anchors, and the ability to fully recapture and reposition the device allowed for optimal deployment are design changes that may have contributed to this notable finding.

Finally, unlike previous studies, the 45 day post implant antithrombotic regimen consisted of aspirin in combination with a DOAC rather than warfarin. The low incidence of peri-procedural pericardial effusion and absence of device related thrombosis in patients who were compliant with medication supports the use of a DOAC and low-dose aspirin as the standard post-procedural antithrombotic regimen.

To conclude, the PINNACLE FLX study results demonstrate the next generation LAA closure device, in combination with a 6-week post-procedural regimen of a DOAC and low-dose aspirin, is associated with a low incidence of safety events and high incidences of effective appendage closure.

Source: Circulation journal: https://doi.org/10.1161/CIRCULATIONAHA.120.050117