Is Aspirin Necessary After Watchman?
Yes, aspirin is necessary after Watchman device implantation and should be continued indefinitely as part of the standard post-procedural antithrombotic regimen. 1
Standard Post-Watchman Antithrombotic Protocol
The American Heart Association has established a three-phase approach following Watchman implantation that includes aspirin throughout all phases 1:
Phase 1: Days 0-45
- Warfarin (INR 2.0-3.0) plus aspirin for at least 45 days post-implantation 1
- This dual therapy period is critical for preventing device-related thrombus formation during the early endothelialization phase 1
- A transesophageal echocardiogram (TEE) should be performed at 45 days to evaluate for device-related thrombus and peridevice leak before discontinuing anticoagulation 1
Phase 2: Days 45 to 6 Months
- Dual antiplatelet therapy (aspirin plus clopidogrel) from 45 days to 6 months post-implantation 1
- Warfarin is discontinued at 45 days if TEE shows no device-related thrombus and acceptable peridevice leak 1
- This transition reduces the risk of intracranial and extracranial hemorrhage while maintaining thromboembolic protection 1
Phase 3: After 6 Months
- Aspirin alone indefinitely after 6 months 1
- Another TEE is recommended at 1 year post-procedure for continued surveillance 1
- Aspirin monotherapy provides ongoing stroke prevention with minimal bleeding risk 1
Evidence Supporting This Regimen
The PROTECT-AF trial demonstrated that LAA closure with the Watchman device was noninferior to warfarin for preventing stroke, systemic embolism, and cardiovascular death (relative risk 0.62,95% CI 0.35-1.25) 1. Importantly, hemorrhagic stroke was significantly lower with the Watchman device compared to long-term warfarin (relative risk 0.09,95% CI 0-0.45) 1.
Special Considerations for High Bleeding Risk Patients
For patients with absolute contraindications to oral anticoagulation, alternative regimens have been studied 2, 3:
- Dual antiplatelet therapy alone (aspirin plus clopidogrel for 6 months, then aspirin indefinitely) may be feasible in patients who cannot tolerate any anticoagulation 2
- Retrospective data suggests that shortened periods of anticoagulation with earlier transition to antiplatelet therapy may be considered in high bleeding risk patients, though this remains off-label 3
- The FDA approval specifies that patients must be deemed suitable for at least short-term warfarin and can tolerate at least 45 days of postprocedural anticoagulation 1
Critical Pitfalls to Avoid
Do not discontinue aspirin prematurely. The indefinite continuation of aspirin after 6 months is essential because 1:
- Any peridevice leak detected by TEE, regardless of size, is associated with increased risk of thromboembolism 1
- Device-related thrombus can occur even after the initial healing period, particularly in patients with non-paroxysmal atrial fibrillation (OR 1.90-2.24), renal insufficiency (OR 4.02), or history of TIA/stroke (OR 2.31) 1
- Detection of high-grade hypoattenuated thickening (device-related thrombus) is significantly associated with increased stroke risk (HR 4.6) 1
Monitor closely during the initial 3-month period after starting warfarin, particularly in elderly patients, to minimize bleeding risk 1. The initial 45-day period requires close anticoagulation monitoring due to high risk of bleeding 1.
Aspirin Dosing
The recommended aspirin dose is 81-162 mg daily 1. While the original trials used doses of 100-325 mg daily, lower doses (81 mg) are widely used in clinical practice and meet the requirements for this indication, as they minimize bleeding risk while maintaining efficacy 4.