Aspirin and postoperative bleeding after coronary artery bypass grafting.
OBJECTIVE
To evaluate the relationship between aspirin ingestion and postoperative bleeding complications, and to test the hypothesis that there is a subset of patients who are aspirin hyperresponders with a proclivity toward platelet dysfunction.


BACKGROUND
Despite numerous retrospective and prospective analyses, it is still controversial as to whether aspirin ingestion before coronary artery bypass grafting (CABG) is associated with significant postoperative bleeding.


METHODS
Between January 1995 and December 1999, the records of 2,606 consecutive patients undergoing CABG were reviewed to identify patients with a history of aspirin ingestion up until the time of surgery. Aspirin ingestion was correlated with postoperative blood transfusion using multivariate analysis. In a subset of preoperative aspirin users (n = 40), bleeding times were measured before and after aspirin use. Flow cytometry was performed in another cohort of patients with known heart disease (n = 30) to determine the effect of aspirin on platelet surface receptors.


RESULTS
During the 5-year study period, 63% of the CABG patients were identified as aspirin users. Among these, 23.1% required blood transfusions compared with 19% for the nonusers. Non-red blood cell transfusions were more common in aspirin users, as was reexploration for bleeding. Stratification of these results according to the frequency of aspirin use showed that aspirin is an independent multivariate predictor of postoperative blood transfusion only in high-risk patients. In the prospective studies, aspirin treatment resulted in a significant increase in the template bleeding time, an increase in platelet PAR-1 thrombin receptor activity, and a decrease in the binding of platelets to monocytes.


CONCLUSIONS
The findings support the hypothesis that aspirin is associated with a greater likelihood of postoperative bleeding. A platelet function testing algorithm that combines preoperative risk factor assessment, template bleeding times, and flow cytometry may allow the identification of aspirin hyperresponders who are at increased risk for bleeding.
Ferraris
Victor A
VA
Division of Cardiothoracic Surgery, University of Kentucky College of Medicine, Lexington 40536-0084, USA. vferr2@uky.edu
Ferraris
Suellen P
SP
Joseph
Oji
O
Wehner
Paulette
P
Mentzer
Robert M
RM
D001241:Aspirin / Q000009:adverse effects* / Q000494:pharmacology; D001760:Bleeding Time; D001803:Blood Transfusion; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D005434:Flow Cytometry; D006801:Humans; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects* / Q000494:pharmacology; D010980:Platelet Membrane Glycoproteins / Q000187:drug effects; D019106:Postoperative Hemorrhage / Q000453:epidemiology / Q000209:etiology*; D012189:Retrospective Studies; D012307:Risk Factors
D010975:Platelet Aggregation Inhibitors; D010980:Platelet Membrane Glycoproteins; D001241:Aspirin