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Antithrombotic Therapy in Peripheral Arterial Occlusive Disease: Carotid Endarterectomy

In patients undergoing carotid endarterectomy, aspirin therapy may be an important adjunct. The goal of antithrombotic therapy in this setting is to prevent immediate, perioperative, and long-term neurologic complications stemming from thrombus formation at the endarterectomy site. Scintigraphic studies with indium-ill-labeled platelets document marked deposition of platelets at the endarterectomy site immediately after operation. The intensity of platelet accumulation decreases over time, possibly because of re-endothelialization of the endarterectomy site. In one study (level II), treatment of patients undergoing carotid endarterectomy with aspirin plus dipyridamole significandy decreased indium-111 platelet deposition and appeared to decrease the incidence of perioperative stroke. A much larger study assessing the benefit of aspirin therapy for longer periods after carotid endarterectomy has been reported (level I). Patients receiving aspirin, 650 mg twice daily started on the fifth postoperative day, had a slight but significant reduction in unfavorable end points when considered together (continuing transient ischemic attacks [TIAs], stroke, retinal infarction, and death from stroke) during a 2-year follow-up period in comparison with control subjects receiving placebo. This experience contrasts with that of a large randomized trial (level I) comparing very-low-dose aspirin therapy, 50 to 100 mg/d, with placebo after carotid endarterectomy. Therapy was started 1 week to 3 months after operation and no significant benefit of veiy-low-dose aspirin therapy was detectable. However, as with lower-extremity bypass operations, the timing of perioperative aspirin therapy may be critical, with late postoperative initiation of therapy being too late to be beneficial. This is suggested by a level I randomized, double-blind trial of aspirin, 75 mg/d, vs placebo; therapy was started preoperatively and was associated with a marked reduction in intra- and postoperative stroke. Recent data from the North American Symptomatic Carotid Endarterectomy Trial (NASCET) may shed additional light on the role of aspirin therapy and dosage after endarterectomy. Perioperative stroke occurring less than 30 days after carotid endarterectomy was significantly lower among NASCET patients receiving relatively high-dose aspirin therapy (325 to 650 mg twice daily) in comparison to those receiving no aspirin or aspirin, 325 mg/d (level III). This striking finding was found on post hoc subgroup analysis and needs to be confirmed by a randomized study. The Aspirin for Carotid Endarterectomy (ACE) trial is addressing this issue and is nearing completion. flovent inhaler

Category: Antithrombotic Therapy

Tags: antithrombotic therapy, aspirin therapy, thrombotic occlusion