Short-term prevention of thromboembolic complications in patients with atrial fibrillation with aspirin plus clopidogrel: The Clopidogrel-Aspirin Atrial Fibrillation (CLAAF) pilot study

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We evaluated the short-term safety and efficacy of aspirin-plus-clopidogrel as antithrombotic therapy in nonvalvular atrial fibrillation (AF).

Methods and results

Thirty patients (11 women, 45 to 75 years of age) with non-high–risk permanent (n = 12) or persistent AF awaiting cardioversion (n = 18) underwent transesophageal echocardiography to exclude left heart thrombi and were then randomly assigned to receive warfarin (international normalized ratio, 2 to 3 for 3 weeks) or aspirin (100 mg/d alone for 1 week)-plus-clopidogrel (75 mg/d added to aspirin for 3 weeks). Bleeding time and serum thromboxane B2 were measured at entry and at 3 weeks. Bleeding time, not affected by warfarin, was prolonged by 71% by aspirin (P < .05) and further, by 144%, by adding clopidogrel (P < .01 vs aspirin alone; +319%, P < .01, vs baseline). Thromboxane B2, not affected by warfarin, was reduced by aspirin (−98%, P < .01) but not further by clopidogrel. No thrombi or dense spontaneous echo-contrast were found at the 3-week transesophageal echocardiography. Seven of 9 patients receiving warfarin and 7 of 9 patients receiving aspirin-plus-clopidogrel, undergoing electrical cardioversion, achieved sinus rhythm. No thromboembolic or hemorrhagic events occurred in both arms throughout the 3-week treatment and a further 3-month follow-up.


Aspirin-plus-clopidogrel and warfarin were equally safe and effective in preventing thromboembolism in this small group of patients with non–high-risk AF.

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