Background—Aortic arch plaques are a risk factor for ischemic stroke. Although the stroke mechanism is conceivably thromboembolic, no randomized studies have evaluated the efficacy of antithrombotic therapies in preventing recurrent events.

Methods and Results—The relationship between arch plaques and recurrent events was studied in 516 patients with ischemic stroke who were double-blindly randomized to treatment with warfarin or aspirin as part of the Patent Foramen Ovale in Cryptogenic Stroke Study (PICSS), based on the Warfarin-Aspirin Recurrent Stroke Study (WARSS). Plaque thickness and morphology were evaluated by transesophageal echocardiography. End points were recurrent ischemic stroke or death over a 2-year follow-up. Large plaques (4 mm) were present in 19.6% of patients; large complex plaques (those with ulcerations or mobile components) were seen in 8.5%. During follow-up, large plaques were associated with a significantly increased risk of events (adjusted hazard ratio [HR], 2.12; 95% confidence interval [CI], 1.04 to 4.32), especially those with complex morphology (HR, 2.55; 95 CI, 1.10 to 5.89). The risk was highest among cryptogenic stroke patients, both for large plaques (HR, 6.42; 95% CI, 1.62 to 25.46) and large complex plaques (HR, 9.50; 95% CI, 1.92 to 47.10). Event rates were similar in the warfarin and aspirin groups in the overall study population (16.4% versus 15.8%; P=0.43).

Conclusions—In patients with stroke, especially cryptogenic stroke, large aortic plaques remain associated with an increased risk of recurrent stroke and death at 2 years despite treatment with warfarin or aspirin. Complex plaque morphology confers a slight additional increase in risk.