***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVES The purpose of our multicenter study was to examine the impact of pre-operative administration of clopidogrel on reoperation rates , incidence of life-threatening bleeding , inpatient length of stay , and other bleeding-related outcomes in acute coronary syndrome ( ACS ) patients requiring cardiopulmonary bypass ( coronary artery bypass graft surgery [ CABG ] ) in a broad cross section of U.S. hospitals . BACKGROUND There is relative uncertainty about the relationship between clopidogrel and CABG-associated outcomes in the setting of ACS . METHODS A retrospective cohort analysis was performed of r and omly selected ACS patients requiring CABG in 14 hospitals across the U.S. Patients exposed to clopidogrel were compared with those not exposed to clopidogrel within 5 days prior to surgery . RESULTS Of the 596 patients enrolled in the study , 298 had been exposed to clopidogrel within 5 days ( Group A ) . Patients in Group A were more than 3-fold more likely to require reoperation for assessment of bleeding than patients not exposed to clopidogrel ( 6.4 % vs. 1.7 % Group B , p = 0.004 ) . Major bleeding occurred in 35 % of Group A patients versus 26 % of Group B patients ( p = 0.049 ) . Length of stay was greater in Group A compared with Group B ( 9.7 + /- 6.0 days vs. 8.6 + /- 4.7 days , unadjusted p = 0.016 ) . After logistic regression analysis , clopidogrel exposure within 5 days of CABG was the strongest predictor of reoperation ( odds ratio [ OR ] : 4.60 , 95 % confidence interval [ CI ] : 1.45 to 14.55 ) and major bleeding ( OR : 1.824 , 95 % CI : 1.106 to 3.008 ) . CONCLUSIONS After ACS , patients who undergo CABG within 5 days of receiving clopidogrel are at increased risk for reoperation , major bleeding , and increased length of stay . These risks must be balanced by the clinical benefits of clopidogrel use demonstrated in r and omized clinical trials BACKGROUND There is evidence that clopidogrel ( with or without aspirin ) confers superior outcomes in patients with coronary artery disease . The purpose of this study is to review the effect of preoperative clopidogrel administration on clinical outcome , bleeding complications and re source utilization after coronary artery bypass graft surgery . METHODS Patient data were prospect ively collected from 919 patients who had isolated coronary surgery during the period 2000 to 2003 . Outcome comparisons were studied , firstly between patients who received preoperative clopidogrel with those who did not , and secondly between patients on clopidogrel only , aspirin only , both or neither medications . RESULTS Twenty-four patients ( 2.6 % ) were on clopidogrel only , 598 ( 65.1 % ) were on aspirin only , 61 ( 6.6 % ) were on both , and 236 ( 25.7 % ) were on neither . Clopidogrel ( n = 85 ) versus no clopidogrel ( n = 834 ) : there were no significant differences in the off-pump patients . In the on-pump patients , the clopidogrel group had significantly increased bleeding ( p = 0.02 ) , blood transfused ( p = 0.01 ) , intensive care ( p = 0.03 ) , and hospital stays ( p = 0.03 ) . There were no significant differences in surgical reexploration , perioperative myocardial infa rct ion , intraoperative balloon pump use , inotropic support or 30-day mortality .  Clopidogrel versus aspirin versus both versus neither : patients on both clopidogrel and aspirin had significantly more postoperative bleeding than patients on aspirin alone or on neither medication . CONCLUSIONS The preoperative use of clopidogrel in patients undergoing coronary artery bypass graft surgery showed limited clinical benefits ; however , its use significantly increased the risk of bleeding , blood transfusion , and re source utilization Background —Aspirin is beneficial in the setting of atherosclerotic cardiovascular disease . There are limited data evaluating preoperative aspirin administration preceding coronary artery bypass grafting and associated postoperative outcomes . Methods and Results —Using prospect ively collected data from 1636 consecutive patients undergoing first-time isolated coronary artery bypass surgery at our institution from January 2000 through December 2002 , we evaluated the association between aspirin usage within the 5 days preceding coronary bypass surgery and risk of adverse in-hospital postoperative events . A logistic regression model , which included propensity scores , was used to adjust for remaining differences between groups . Overall , there were 36 deaths ( 2.2 % ) and 48 adverse cerebrovascular events ( 2.9 % ) in the postoperative hospitalization period . Patients receiving preoperative aspirin ( n=1316 ) had significantly lower postoperative in-hospital mortality compared with those not receiving preoperative aspirin [ 1.7 % versus 4.4 % ; adjusted odds ratio ( OR ) , 0.34 ; 95 % CI , 0.15 to 0.75 ; P=0.007 ] . Rates of postoperative cerebrovascular events were similar between groups ( 2.7 % versus 3.8 % ; adjusted OR , 0.67 ; 95 % CI , 0.32 to 1.50 ; P=0.31 ) . Preoperative aspirin therapy was not associated with an increased risk of reoperation for bleeding ( 3.5 % versus 3.4 % ; P=0.96 ) or requirement for postoperative blood product transfusion ( adjusted OR , 1.17 ; 95 % CI , 0.88 to 1.54 ; P=0.28 ) . Conclusions —Aspirin usage within the 5 days preceding coronary artery bypass surgery is associated with a lower risk of postoperative in-hospital mortality and appears to be safe without an associated increased risk of reoperation for bleeding or need for blood product transfusion OBJECTIVES This study was design ed to evaluate the effect of preoperative clopidogrel on coronary artery bypass graft surgery ( CABG ) outcomes . BACKGROUND Clopidogrel in combination with aspirin , given before percutaneous coronary intervention , has become the st and ard for stent thrombosis prevention . Some premedicated patients , however , are found to have surgical disease on angiography , and irreversible platelet inhibition becomes a concern for upcoming CABG . METHODS We prospect ively studied 224 consecutive patients undergoing nonemergent first-time CABG  , and compared those with preoperative clopidogrel exposure within seven days ( n = 59 ) to those without exposure ( n = 165 ) . RESULTS The groups were comparable in age , gender , body surface area , preoperative hematocrit , preoperative prothrombin time and prior myocardial infa rct ion . The clopidogrel group had higher 24-h mean chest tube output ( 1,224 ml vs. 840 ml , p = 0.001 ) , and more transfusions of red blood cells ( 2.51 U vs. 1.74 U , p = 0.036 ) , platelets ( 0.86 U vs. 0.24 U , p = 0.001 ) and fresh frozen plasma ( 0.68 U vs. 0.24 U , p = 0.015 ) . Moreover , reoperation for bleeding was 10-fold higher in the clopidogrel group ( 6.8 % vs. 0.6 % , p = 0.018 ) . The clopidogrel group also had less extubation within 8 h ( 54.2 % vs. 75.8 % , p = 0.002 ) and a trend towards less hospital discharge within five days ( 33.9 % vs. 46.7 % , p = 0.094 ) . CONCLUSIONS Clopidogrel in combination with aspirin before CABG is associated with higher postoperative bleeding and morbidity . These findings raise concern regarding the routine administration of clopidogrel before anticipated coronary stent implantation Background —Antiplatelet therapy and antithrombin therapy have been demonstrated to reduce the risk of cardiac events in patients presenting with acute coronary syndrome , yet all effective therapies also increase the risk of bleeding . Methods and Results —In the Clopidogrel in Unstable angina to prevent Recurrent ischemic Events ( CURE ) trial , 12 562 patients were r and omized to clopidogrel or placebo  in addition to  aspirin  , and the primary outcome was cardiovascular ( CV ) death , myocardial infa rct ion ( MI ) , or stroke . The benefits were consistent among those undergoing percutaneous coronary intervention ( PCI ) [ 9.6 % for clopidogrel , 13.2 % for placebo ; relative risk ( RR ) , 0.72 ; 95 % CI , 0.57 to 0.90 ] , coronary artery bypass grafting ( CABG ) surgery ( 14.5 % for clopidogrel 16.2 % for placebo ; RR , 0.89 ; 95 % CI , 0.71 to 1.11 ) , and medical therapy only ( 8.1 % for clopidogrel , 10.0 % for placebo ; RR , 0.80 ; 95 % CI , 0.69 to 0.92 ; test for interaction among strata , 0.53 ) . For CABG during the initial hospitalization ( 530 for placebo , 485 for clopidogrel ) , the frequency of CV death , MI or stroke before CABG was 4.7 % for placebo and 2.9 % for clopidogrel ( RR , 0.56 ; 95 % CI , 0.29 to 1.08 ) . For the entire study , there was a 1 % excess of major bleeding but no significant excess of life-threatening bleeding . Among patients undergoing CABG , the rates of life-threatening bleeding were 5.6 % for clopidogrel and 4.2 % for placebo ( RR , 1.30 ; 95 % CI , 0.91 to 1.95 ; both nonsignificant ) . Conclusions —The benefits versus risks of early and long-term clopidogrel therapy ( freedom from CV death , MI , stroke , or life-threatening bleeding ) are similar in those undergoing revascularization ( CABG or PCI ) and in the study population as a whole . Overall , the benefits of starting clopidogrel on admission appear to outweigh the risks , even among those who proceed to CABG during the initial hospitalization OBJECTIVE The optimal timing for discontinuation of clopidogrel before surgery remains under debate . The purpose of this study is to determine the effect of preoperative clopidogrel administration on postoperative blood loss and the total requirements of homologous blood products after coronary artery bypass grafting ( CABG ) . We also evaluated the perioperative complications . METHODS Consecutive patients ( n=130 ) undergoing elective CABG were recruited and r and omised between 2006 and 2007 . In 38 patients ( group 1 ) , treatment with clopidogrel was discontinued 5 days prior to surgery , in 40 patients ( group 2 ) 3 days before surgery and in 40 other patients ( group 3 ) clopidogrel was stopped on the day of surgery . RESULTS Significantly more postoperative blood loss was observed in group 3 compared to group 1 ( 929+/-472 ml vs 664+/-312 ml ; p=0.009 ) . Other group comparisons were not significant . Blood loss after 12 h and at drain removal was also significantly higher in group 3 . Patients in group 3 also had higher total requirements of homologous blood products ( p=0.046 ) and a significantly higher need for fresh frozen plasma ( FFP ) transfusion ( p=0.034 ) . Univariable regression analyses revealed that continuing clopidogrel till the day of surgery ( group 3 ) was predictive for postoperative blood loss ( beta=0.289 ; p=0.007 ) and the total requirements of homologous blood products after surgery ( beta=0.280 ; p=0.008 ) . These effects remained the same in multivariable analyses . CONCLUSIONS Continuation of clopidogrel until the day of surgery induces significantly more postoperative blood loss and increases significantly the total requirements of homologous blood products and FFP transfusion after surgery . The blood loss and the use of blood products in the group that stopped at 3 days preoperatively were similar to that of the group that stopped at 5 days preoperatively AIMS Aspirin combined with clopidogrel is the treatment of choice for acute coronary syndromes . Although the maintenance of aspirin until surgery does not affect postoperative bleeding after coronary artery bypass graft ( CABG ) surgery , the latter may be dramatically increased when clopidogrel is continued over a period of 5 days preoperatively . METHODS AND RESULTS This prospect i ve observational study included 217 consecutive patients scheduled for first-time CABG .  Postoperative bleeding and blood 
    Output:
    
These data support withholding thienopyridines 5 days before cardiac surgery ; there was insufficient evidence to make definitive recommendations for elective noncardiac surgery although the direction and magnitude of associations were similar