The effects of recent aspirin ingestion on platelet function in cardiac surgical patients.
OBJECTIVE
To examine the effects of the preoperative aspirin-free interval on platelet function in cardiac surgical patients.


METHODS
Prospective clinical investigation.


METHODS
University-affiliated teaching hospital.


METHODS
Patients undergoing elective coronary artery bypass graft surgery (n = 100).


METHODS
The patients were divided into 3 groups based on the number of days since they last ingested aspirin: < or =2 days, 3 to 7 days, and >7 days. Preoperative platelet function was assessed in all patients using platelet aggregation responses to arachidonic acid, 5 microg/mL, and Platelet Function Analyser (PFA100) collagen/epinephrine closure times.


RESULTS
Patients who ceased aspirin < or =2 days preoperatively had weaker platelet aggregation responses (18.5% +/- 7% maximum aggregation, mean +/- SD, n = 36) than patients who ceased aspirin 3 to 7 days preoperatively (68.8% +/- 29%, n = 48, p < 0.001) or >7 days preoperatively (68.3% +/- 28%, n = 16, p < 0.001). Similarly, patients who ceased aspirin < or =2 days preoperatively had longer PFA100 closure times (168 +/- 52 sec) than patients who ceased aspirin 3 to 7 days preoperatively (122 +/- 43 sec, p < 0.001) or >7 days preoperatively (128 +/- 42 sec, p < 0.01). The percentage of abnormal responses was also greatest in the aspirin < or =2 days group.


CONCLUSIONS
Cardiac surgical patients who ingest aspirin < or =2 days preoperatively have greater impairment of platelet function than patients who have a longer preoperative aspirin-free interval.
Department of Anaesthesia, Sir Charles Gairdner Hospital, and PathCentre, Nedlands, Western Australia.
N M
NM
Gibbs
W M
WM
Weightman
N M
NM
Thackray
N
N
Michalopoulos
C
C
Weidmann
D000368:Aged; D000758:Anesthesia; D001241:Aspirin / Q000009:adverse effects*; D001792:Blood Platelets / Q000187:drug effects*; D006348:Cardiac Surgical Procedures; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects*; D010979:Platelet Function Tests; D019106:Postoperative Hemorrhage / Q000097:blood; D011446:Prospective Studies; D013997:Time Factors
D010975:Platelet Aggregation Inhibitors; D001241:Aspirin