Effect of preoperative aspirin on blood lossand blood transfusion in patients undergoingcoronary artery bypass grafting: Impactof discontinuation prior to surgery

The aim of our study is to evaluate the impact of recent aspirin use before CABG on the post operative bleeding, blood transfusion and re-exploration. Retrospectively collected data from 67 patients who were operated in Sultan Qaboos University Hospital from 2008-2009 was included in this study. Patients were divided into two groups, [1] Aspirin stopped >7 days before surgery [34 patient] and [2] Aspirin received within 7 days before surgery [33 patients]. Platelet transfusion and length of hospital stay was more in patients where Aspirin stopped < 7 days [P value 0.03 and 0.002 respectively]. There was trend of increase in intraoperative bleeding and PRBC transfusion in the group who received Aspirin within seven days. Postoperative blood loss was higher in aspirin users than non aspirin users but not statistically significant. There was no difference between two groups regarding re-exploration or operative mortality. Patients who take aspirin within 7 days before surgery have more tendency to have post-operative bleeding and receiving blood products. They also have longer length of stay in the hospital. Our recommendation is to stop aspirin more than 7 days before surgery

Variability in platelet response to a single daily dose of 150 mg enteric coated aspirin in a high risk population.

PURPOSE: Previous studies have reported inadequate anti-platelet effect in 0.4-35% of patients taking aspirin. Such studies have arbitrarily defined the terms "semi-responders", "non-responders" or "resistant" to variable doses of aspirin on the basis of absolute values derived from different ex-vivo platelet aggregation (PA) methods. Our objective was to define response to 150-mg dose of aspirin in terms of normally distributed values using an ex-vivo measure of PA in a population at high risk for vascular events. METHODS: We prospectively studied high risk patients with either established coronary artery disease (CAD) or stroke or transient ischemic attack (TIA) or peripheral vascular disease or with multiple atherothrombotic risk factors like diabetes plus one of the following-- hypertension, increased total cholesterol, cigarette smoking, micro-albuminuria, low-high density lipoprotein (HDL), family history of CAD and receiving single 150 mg dose of aspirin daily. PA was assessed by chronolog lumi-aggregometer (490-2D) using arachidonic acid (AA) reagent. RESULTS: 130 patients were studied. The response of subjects to aspirin followed a normal, bell shaped distribution curve with a mean and standard deviation (S.D.) of 13.1 +/- 4.4%. 3.1% patients had PA values more than 2 S.D. of the mean, hence termed as hypo-responders to aspirin while another 3.1% patients had PA values less than 2 S.D. of the mean, hence termed as hyper-responders to aspirin. CONCLUSION: There is minimal inter-individual variability in the response to aspirin when tested with AA as the reagent. The response to aspirin follows a normal Gaussian distribution. The prevalence of hypo-responders to aspirin in high risk population is only 3.1%. This is the first study to document "hypo" and "hyper-responders" to single daily dose of 150 mg aspirin. The clinical relevance of these findings remains to be determined.