Anti-platelet effect of aspirin is substantially reduced after administration of heparin during carotid endarterectomy.

Objectives: Aspirin therapy is usually continued throughout the perioperative period to reduce the risk for thromboembolic stroke and myocardial infarction after carotid endarterectomy (CEA). Aspirin irreversibly binds cyclooxygenase-1, thereby reducing platelet aggregation for the lifetime of each platelet. However, recent research from this unit has shown that aggregation in response to arachidonic acid increases significantly, but transiently, during CEA, which suggests that the anti-platelet effect of aspirin is temporarily reversed.

Platelet inhibition by aspirin is diminished in patients during carotid surgery: a form of transient aspirin resistance?

The majority of patients who suffer peri-operative thromboembolic complication while undergoing vascular procedures do so despite taking aspirin. This study examined the antiplatelet effect of aspirin during surgery in patients undergoing carotid endarterectomy (CEA). Fifty patients undergoing CEA were standardised to 150 mg aspirin daily for > or =2 weeks.