The WATCHMAN FLX left atrial appendage (LAA) closure device maintained its safety and efficacy through 2 years after implantation in patients with nonvalvular atrial fibrillation (NVAF), according to late-breaking trial results presented Wednesday at Transcatheter Valve Therapies (TVT) 2021.
LAA occlusion provides an alternative to oral anticoagulation for thromboembolic risk reduction in patients with NVAF. Since device approval in 2015, the WATCHMAN device (Boston Scientific) has been the only LAA closure device available for clinical use in the United States.
The PINNACLE FLX study (Protection Against Embolism for Nonvalvular AF Patients: Investigational Device Evaluation of the Watchman FLX LAA Closure Technology) evaluated the safety and effectiveness of the next-generation WATCHMAN FLX LAA closure device in patients with NVAF in whom oral anticoagulation is indicated but who have an appropriate rationale to seek a nonpharmaceutical alternative. The 1-year results were published in Circulation in April.
PINNACLE FLX was a prospective, nonrandomized, multicenter study. In the primary outcome phase of this trial, the primary safety endpoint was the occurrence of one of the following events within 7 days after the 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 ≤5 mm), as assessed by the echocardiography core laboratory at 12-month follow-up. A key secondary efficacy endpoint was ischemic stroke or systemic embolism at 2 years.
In comparing WATCHMAN with WATCHMAN FLX, Saibal Kar, MD, of Los Robles Health System, Thousand Oaks, California, said the WATCHMAN FLX has a larger range, is a shorter device, has dual-row anchors, folded-back distal tines, a greater number of struts and reduced metal exposure.
Kar presented the first report of 2-year outcomes with a next-generation LAA closure device, the final results from the PINNACLE FLX IDE trial, at TVT in Miami Beach, Florida.
The trial enrolled 400 patients. Their mean age was 73.8±8.6 years, and their mean CHA2DS2-VASc score was 4.2±1.5. The incidence of the primary safety endpoint was 0.5% with a one-sided upper bound of the 95% confidence interval (CI) of 1.6%, meeting the performance goal of 4.2% (P<0.0001). The incidence of the primary effectiveness endpoint was 100%, with a one-sided lower bound of the 95% CI of 99.1%, again meeting the performance goal of 97.0% (P<0.0001), as reported in the manuscript describing the 1-year results. Device-related thrombus was reported in seven patients, no patients experienced pericardial effusion requiring open cardiac surgery, and there were no device embolizations.
Through 2 years, 95.3% of patients were on aspirin, 6.2% on dual antiplatelet therapy (DAPT) and 7.1% on oral anticoagulation (OAC). This was a marked shift from 7-day discharge, when 99.7% of patients were on OAC, none were on DAPT, and 99.5% were on aspirin.
At 2 years, 3.4% of patients experienced ischemic stroke or systemic embolism (one more patient with an ischemic event after 1 year), and 1.8% had device-related thrombus (DRT; no additional DRTs reported after 1 year).. Kar said the one-sided upper bound of the 95% CI of 5.3% was less than the prespecified performance goal of 8.7%.
Two-year clinical outcomes manifested as all-cause death (9.3% of patients), cardiovascular death (5.5%), any stroke (3.4%), ischemic stroke (3.1%), hemorrhagic stroke (0.3%) and systemic embolism (0.3%).
Kar concluded that the PINNACLE FLX investigators observed sustained safety and efficacy outcomes through 2 years and the key secondary endpoint was met. While between year 1 and 2 only one patient had an ischemic event, there were no additional DRT or pericardial effusions requiring intervention beyond those reported at 1 year. Finally, the WATCHMAN FLX showed no device embolization through 2 years.
The PINNACLE FLEX IDE trial funded Boston Scientific.