ASA Plavix Feasibility Study with WATCHMAN™ Left Atrial Appendage Closure Technology
The PROTECT AF trial demonstrated that LAA closure with the Watchman device was non-inferior to warfarin therapy. However, PROTECT AF only included patients that were candidates for warfarin, and even patients randomised to the LAA closure arm received concomitant warfarin for 6 weeks after Watchman implantation.
AF patients who are contraindicated or intolerant of warfarin have few options for thromboembolic prophylaxis. Patients may be treated with aspirin and/or clopidogrel, but this treatment paradigm has a higher stroke risk than warfarin.
The ASAP registry, a non-randomized feasibility study, was designed to assess the safety and efficacy of left atrial appendage closure (LAA) in nonvalvular atrial fibrillation (AF) patients ineligible for warfarin therapy.
150 AF patients contraindicated for long-term warfarin therapy were included in the ASAP Registry. Patients were enrolled at 4 European centers.
- Average CHADS2 = 2.8; Average CHADS2 -VASc score was 4.4
- Mean age of the patient population was 72.5 (+/- 4.4 years) and the mean patient follow-up was 14.4 months
The reason for warfarin contraindication was:
- Hemorrhagic/bleeding tendencies (93%)
- Blood dyscrasias (7.3%)
- Unsupervised senility/high fall risk (4%)
- Other (5.3%)
- A total of 61 patients (40.7%) had a prior stroke or TIA
Post procedure anti-platelet regimen
- Clopidogrel through 6 months
- Aspirin indefinitely
Patients were followed for up to 1 year
- Follow-up was done at 3, 6, 12, 18 & 24 months
- TEE at 3 and 12 months
The mean CHADS2 score in the ASAP population was 2.8, which equates to a predicted ischemic stroke rate of 7.4% per year using data from a cohort of hospitalized AF patients, and assuming no aspirin use1. If this expected stroke rate of 7.4% per year is averaged with data in which aspirin was used 2 the expected ischemic stroke of the ASAP population is approximately 7.3%
The ASAP registry demonstrated a 77% reduction in ischemic stroke in warfarin contra-indicated patients vs. Aspirin alone and a 64% reduction vs. aspirin and clopidogrel.
All-cause stroke or systemic embolism occurred in 4 patients (2.3% per year); ischemic stroke in 3 patients (1.7% per year) and hemorrhagic stroke in 1 patient (0.6% per year). The strokes occurred in patients with a prior history of stroke or TIA. A total of 9 patients (5.0% per year) died during the follow-up period (cardiovascular, n=3; cancer, n=2; other, n=4); none were device or procedure related. The cardiovascular and non-cardiovascular deaths occurred at a median of 406 and 209 days post-implant, respectively.
Left Atrial Appendage Closure with the WATCHMAN device produced a significant reduction in the expected ischemic stroke rate for patients contraindicated to warfarin.
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