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Edward Lee Carter: Is Aspirin Monotherapy Sufficient After Watchman Implantation?

Edward Lee Carter/LinkedIn

Nov 7, 2026, 13:50

Edward Lee Carter: Is Aspirin Monotherapy Sufficient After Watchman Implantation?

Edward Lee Carter, Clinical Pharmacist Practitioner at U.S. Department of Veterans Affairs, shared a post on LinkedIn:

“After Watchman implantation, could aspirin alone be enough?

A new randomized trial suggests that more antithrombotic therapy may not mean better outcomes following left atrial appendage closure (LAAC).

Presented at TCT 2026 and published November 2 in JAMA, the SIMPLAAFY trial challenges routine dual antiplatelet therapy (DAPT) after contemporary Watchman implantation.

1,857 patients
87 U.S. centers
Watchman FLX Pro

Three postimplant strategies were evaluated:

DAPT for 6 months, then aspirin
Reduced-dose DOAC for 3 months, then aspirin
Aspirin alone

The DOAC strategy primarily involved apixaban 2.5 mg twice daily.

Six-month primary composite

death
stroke
systemic embolism
major bleeding

DAPT: 6.9%

Reduced-dose DOAC: 5.1%
Aspirin alone: 3.3%

Both monotherapy strategies met prespecified noninferiority criteria versus DAPT.

But here’s where the findings become particularly interesting.

Major bleeding

DAPT: 4.5%
Reduced-dose DOAC: 2.7%
Aspirin: 1.7%

Device-related thrombus at 45 days

DAPT: 3.4%
Reduced-dose DOAC: 0.9%
Aspirin: 2.7%

Ischemic stroke occurred in 0.7% of each group.

Aspirin alone had the lowest observed bleeding rate, while reduced-dose DOACs had the lowest observed device-related thrombus rate.

That distinction matters.

Before changing clinical protocols:

The noninferiority margin was relatively large (7.2 percentage points), although observed confidence bounds were reassuring.

Secondary bleeding and device-thrombosis comparisons were exploratory. The trial was not powered to establish equivalence for individual ischemic outcomes or superiority of aspirin over reduced-dose DOACs.

Only Watchman FLX Pro was studied, and longer-term outcomes remain pending.

My clinical pharmacy takeaway:

SIMPLAAFY raises an important question: Are we exposing some patients to unnecessary bleeding risk by routinely prescribing DAPT after uncomplicated LAAC?

The findings support reconsidering antithrombotic intensity—not abandoning individualized risk assessment.

Device characteristics, bleeding history, thrombotic risk, other anticoagulation indications, and follow-up imaging still matter.

SIMPLAAFY challenges routine DAPT—not the need for thoughtful anticoagulation stewardship.

The views expressed are my own and do not represent the official positions or policies of the U.S. Department of Veterans Affairs or the U.S. government”.

Edward Lee Carter: Is Aspirin Monotherapy Sufficient After Watchman Implantation?