An evaluation of cyclooxygenase-1 inhibition before coronary artery surgery: aggregometry versus patient self-reporting.

Background: Platelet dysfunction due to antiplatelet therapy contributes to perioperative bleeding. Several trials investigating the influence of aspirin intake within the 5 days before surgery reported that transfusion requirements were either increased or not significantly affected by aspirin intake. Our objective was to compare the assessment of aspirin intake by patient self-reporting and by measurement of platelet function with regard to transfusion requirements.

Methods: In a prospective trial, a standardized questionnaire was used in 100 patients for aspirin intake within the 5 days immediately before coronary artery bypass grafting. Whole blood platelet aggregation triggered by arachidonic acid was investigated using the Multiplate platelet function analyzer.

Results: Eleven of 23 patients with aspirin intake within the 5 days before the intervention showed an abnormal aggregation response. Nine of 77 patients who reported no aspirin intake before surgery had an abnormal aggregation response. There were no significant differences in chest tube drainage and red blood cell transfusion over the first 24 h postoperatively between patients with and without reported aspirin intake. There was no significant difference in chest tube drainage over the first 24 h postoperatively between patients showing normal or abnormal aggregation response. Patients with abnormal aggregation before intervention (<51 U) received significantly more platelet transfusion than patients with normal aggregation (1.1 U compared to 0.3 U, P = 0.001).

Conclusions: Our results suggest that arachidonic acid-induced aggregation in whole blood may be a better predictor of platelet-related coagulopathy and platelet transfusion than the assessment of aspirin intake by patient self-reporting.