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Bleeding post coronary artery bypass surgery. Clopidogrel--cure or culprit?

BACKGROUND
Clopidogrel, in addition to aspirin, has become a common treatment of acute coronary syndrome and for stent thrombosis prevention, when given before percutaneous transluminal coronary angioplasty. However, some patients turn out to have surgical coronary artery disease and are sent for coronary artery bypass grafting (CABG) where the irreversible effect of aspirin and clopidogrel on platelet function becomes a concern. This study was conducted to evaluate the role of preoperative use of clopidogrel in bleeding complications after CABG.


MATERIAL AND METHODS
A total of 462 patients who underwent CABG between 2001 and 2003 were studied as a retrospective cohort. Comparison was made between patients who had taken clopidogrel within 7 days of surgery (n=162), and those who were not exposed to clopidogrel (n=300). Chest tube output and bleeding index (a modified TIMI criteria), were the primary outcomes measured.


RESULTS
Our data showed that patients taking clopidogrel within 7 days of surgery have a higher bleeding index than those who were not exposed to the drug (p = 0.024). Similarly, chest tube output was significantly higher in those who were exposed to clopidogrel within 7 days compared to those not taking clopidogrel (p = 0.01). To further dissect this relationship, we divided our population into three categories. We found that patients taking clopidogrel within 3 days prior to CABG (immediate exposure) have a higher bleeding index and TIMI major bleeding than either patients taking the drug between 3 and 7 days (recent exposure) or patients not exposed to clopidogrel at all (p = 0.009 and 0.03 respectively for inter-groups comparison). The same was true for chest tube output (p = 0.05 and 0.01 respectively).


CONCLUSION
Clopidogrel increased the risk of post-CABG bleeding if taken within three days prior to surgery but not if taken before that.