Watchman left atrial appendage system for embolic PROTECTion in patients with AF (2009)


Prevention of stroke and systemic embolic events in patients with AF

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To evaluate, if the percutaneous closure of the left atrial appendage (LAA) with the Watchman device in patients with AF is non-inferior to oral anticoagulation with warfarin

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Trial design

Prospective randomized controlled trial
Active treatment: percutaneous closure of LAA with the Watchman device (a self-expanding nickel titanium frame structure with fixation barbs and a permeable polyester fabric cover, implanted via a trans-septal approach; diameter 21–33 mm) and subsequent discontinuation of warfarin after complete closure of the LAA. After stopping warfarin treatment, once daily clopidogrel (75 mg) plus ASA (81–325 mg) until completion of the 6-month follow-up visit, thereafter ASA alone continued indefinitely (n=463)
Control treatment: warfarin (INR 2.0–3.0) (n=244)

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Primary efficacy endpoint: composite of stroke (ischemic and hemorrhagic), cardiovascular or unexplained death, and systemic embolism
Primary safety endpoint: composite of major bleeding, pericardial effusion, and device embolization

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Trial participants

707 adult patients (mean age 72 years) with non-valvular AF and at least one additional risk factor for stroke

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Efficacy outcome: After a follow-up of 1065 patient-years, in the intent-totreat population the primary efficacy event rate was 3.0 per 100 patient-years in the intervention group and 4.9 per 100 patient-years in the control group. The probability of non-inferiority of the intervention was >99.9%. In patients with a successful intervention, who discontinued warfarin (n=389), the primary endpoint rate was 1.9 per 100 patient-years compared with 4.6 per 100 patient-years in control patients who received warfarin (n=241)
Safety outcome: The primary safety endpoint occurred at a higher rate in the intervention group than in the control group (relative risk 1.69). In the intervention group, the majority of events occurred on the day of the procedure, in contrast to the control group, in which most events occurred later. At 2 years after randomization, the cumulative primary safety event rate was 10.2% for the intervention group and 6.8% for the control group. In the successfully treated patients, the primary safety event rate was lower in the intervention group than in the control group (relative risk reduction 65%)

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Efficacy: Closing of the LAA was non-inferior to warfarin therapy in the primary efficacy endpoint of all strokes, cardiovascular death and systemic embolic events
Safety: There was a higher rate of primary safety events in the intervention group as compared to the control group. The events in the intervention group were mainly a result of periprocedural complications

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Holmes D, Reddy VY, Turi ZG, Doshi SK, Sievert H, Buchbinder M, Mullin CM, Sick P, fort he PROTECT investigators. Percutaneous closure of the left atrial appendage versus warfarin therapy for prevention of stroke in patients with atrial fibrillation: a randomised non-inferiority trial. Lancet 2009;374:534-542

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Corresponding author

Prof. David R. Holmes, Mayo Clinic, 200 First Street SW, SMH MB 4-523, Rochester, MN 55905, USA, e-mail:

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