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The SIMPLAAFY trial found that aspirin alone and reduced-dose oral anticoagulants were not worse than dual antiplatelet therapy (DAPT) on a combined six-month outcome after successful Watchman FLX Pro implantation. The results may support simpler post-procedure regimens for selected patients, but follow-up beyond six months is pending and the findings do not apply to every patient or implant.
The SIMPLAAFY trial found that aspirin alone and reduced-dose oral anticoagulants were not worse than dual antiplatelet therapy (DAPT) on a combined six-month outcome after uncomplicated left atrial appendage closure with a Watchman FLX Pro device. The findings, presented at the Transcatheter Cardiovascular Therapeutics conference and published in JAMA, could inform a choice of post-procedure treatment, but do not establish one regimen as best for all patients.
Researchers randomized 1,857 people with nonvalvular atrial fibrillation after successful implantation of the Watchman FLX Pro occluder. Participants received aspirin at 81 to 100 mg daily, DAPT for six months, or reduced-dose non-vitamin K oral anticoagulants (NOACs) for three months. The NOAC options were apixaban 2.5 mg twice daily or rivaroxaban 10 mg daily. The assigned drug regimens were followed by aspirin.
At six months, the combined rate of all-cause death, stroke, systemic embolism or major bleeding was 3.3% with aspirin, 6.9% with DAPT and 5.1% with reduced-dose NOACs. The study reported aspirin and reduced-dose NOACs as statistically at least as good as DAPT on this outcome. The reported risk ratio was 0.49 for aspirin (95% confidence interval 0.29-0.82) and 0.75 for NOACs (95% CI 0.48-1.18), each compared with DAPT.
Secondary analyses found no excess stroke at six months in either monotherapy group. Bleeding outcomes favored both monotherapies over DAPT, while device-related thrombus at 45 days was reported in 0.9% of the NOAC group, 2.7% of the aspirin group and 3.4% of the DAPT group. These findings concern separate outcomes and time points; they do not by themselves determine which regimen offers the best overall balance for an individual patient.
A Simpler Regimen After Implant
After left atrial appendage closure, clinicians still need to choose medication to limit clot-related complications while accounting for bleeding risk. SIMPLAAFY adds randomized evidence to a practice area that, according to a discussant, has lacked strong guidance. Its results suggest that DAPT may not be necessary for every patient with an uncomplicated implant, and that aspirin alone merits consideration in this setting.
The comparison matters because antithrombotic medicines can carry bleeding risks, while insufficient protection may allow clots to form on or around the device. In the trial, adherence to assigned medication for at least 80% of days was 87.9% with aspirin, 76.8% with DAPT and 85.3% with NOACs. Saibal Kar, the presenting investigator, said both monotherapy approaches were better tolerated than DAPT. Those adherence figures are a trial observation, not proof that a particular option will be easier or safer for every patient.
The results do not support ending DAPT as a universal practice. Treatment decisions still depend on a patient’s bleeding and clotting risks, implant course and preferences. The study’s limited population and pending longer-term results leave important questions open.
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How SIMPLAAFY Compared Treatments
Left atrial appendage closure is used for some people with nonvalvular atrial fibrillation. The procedure places an occluder to close the appendage, where clots can form. Patients are prescribed antithrombotic medication after implantation, but the best approach has not been consistent across practice. The SIMPLAAFY report described substantial variation, with limited evidence guiding the choice.
The study enrolled patients whose Watchman FLX Pro implant was successful and uncomplicated. The average age was 76, 43% of participants were women, and the mean CHA2DS2-VASc stroke-risk score was 4.2; the mean HAS-BLED bleeding-risk score was 2.6. Acute events through seven days were generally uncommon. Major bleeding rates were 0.2% with aspirin, 0.5% with DAPT and 0.2% with NOACs; clinically relevant nonmajor bleeding rates were 1.0%, 1.6% and 1.5%, respectively.
Another trial complicates interpretation of the NOAC findings. The report noted that ANDES found short-term NOAC treatment was not better than DAPT at preventing device-related thrombus at 60 days. At one year, reported thrombus rates were 5.2% with NOACs and 2.3% with DAPT, a difference that was not statistically significant (P=0.154). This is a separate trial and does not negate SIMPLAAFY’s findings, but it underscores why the medication question remains unsettled.
“These findings support the simplification of antithrombotic management after uncomplicated LAA [closure] and may be individualized according to competing bleeding and device thrombosis risks and patient preferences.”
— Saibal Kar, MD, of Los Robles Hospital and Medical Center, presenting the SIMPLAAFY results
Limits of the Six-Month Evidence
SIMPLAAFY’s reported findings cover six-month clinical outcomes, and the 12-month results are still pending. It is not yet clear whether the apparent differences between groups will persist with longer follow-up or what treatment should be used after the study’s assigned regimens end. The trial also did not prespecify a direct comparison between the aspirin and NOAC groups, so the results cannot establish that one monotherapy is superior to the other.
The trial excluded some groups at higher risk, including people with severe kidney disease, recent stroke, recent myocardial infarction or major bleeding. Its conclusions may not apply to those patients or to procedures with complications. The report also notes that imaging at 45 days found no difference in device seal across groups, but that finding does not settle longer-term thrombus risk. How clinicians should weigh the separate bleeding, thrombus and combined-outcome results remains a matter for further evidence and individualized decisions.
Twelve-Month Results Remain Pending
The next major evidence point is SIMPLAAFY’s 12-month follow-up, which has not yet been reported. Longer follow-up could help show whether the six-month patterns continue and clarify treatment choices after the initial medication periods. Until then, the trial supports discussion of aspirin or reduced-dose NOACs for patients resembling those enrolled, rather than a general change for all people undergoing LAA closure.
Clinicians and researchers will also need to interpret SIMPLAAFY alongside trials such as ANDES, particularly when considering NOACs and device-related thrombus over time. The study report does not provide a universal post-implant protocol or resolve what medication patients should take beyond one year. For now, the confirmed result is narrower: among patients with successful, uncomplicated Watchman FLX Pro implants, aspirin alone and reduced-dose NOACs were not worse than DAPT on the trial’s combined six-month outcome.
Key Questions
Does SIMPLAAFY show that DAPT should stop after LAA closure?
No. The trial found aspirin alone and reduced-dose NOACs were not worse than DAPT on a combined six-month outcome in its enrolled patients. It does not establish a single regimen for everyone or mean DAPT should be stopped without a clinician’s direction.
Which treatment had the lowest combined event rate?
Aspirin alone had the lowest reported six-month rate of the combined outcome: 3.3%, compared with 5.1% for reduced-dose NOACs and 6.9% for DAPT. The study did not prespecify a direct comparison between the two monotherapy groups, so these figures do not prove aspirin is superior to NOACs.
What was the device-related thrombus rate?
At 45 days, device-related thrombus was reported in 0.9% of participants taking reduced-dose NOACs, 2.7% taking aspirin and 3.4% taking DAPT. This is a secondary finding at a specific follow-up point and does not settle longer-term risk.
Who may not be represented by the findings?
The results apply most directly to patients with nonvalvular atrial fibrillation who had a successful, uncomplicated Watchman FLX Pro implant. People with severe kidney disease, recent stroke, recent myocardial infarction or major bleeding were among those excluded, so the findings may not apply to them.
When will longer-term results be available?
The report says 12-month SIMPLAAFY results are pending and does not give a release date. Those data may help clarify how the treatment patterns hold up beyond the six-month results.
Source: medpagetoday.com
