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8/7/2019 Balancing the Benefit and Risk of Oral Antiplatelet Agents in Coronary Artery Bypass Surgery
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Balancing the Benefit and Risk of
Oral Antiplatelet Agents in Coronary
Artery Bypass Surgery The Annals of Thoracic SurgeryVol: 80 Issue: 2, August, 2005
By Intern/P
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Organ reperfusion after coronary
revascularization, particularly when
conducted in conjunction with
cardiopulmonary bypass, is associated with a
diffuse inflammatory response, marked by the
release of proinflammatory cytokines,
activation of complement neutrophils andplatelets, and initiation of intravascular
thrombosis
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Benefits of Oral Antiplatelet Therapy in
CABG Surgery the mainstay ofprimary and secondary
prevention in atherothrombotic disease
broad consensus about the value of long-term aspirin therapy in reducing the risk ofdeath, myocardial infarction, and stroke inpatients at high risk of occlusive vasculardisease, [ 8 ] as well as in preventingischemic complications [ 9 ] and maintainingearly and late vein-graft patency after CABG
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Aortocoronary grafts are susceptible to acute
thrombotic occlusion during the first month after
CABG surgery and, subsequently, to atherosclerotic
obstruction [ 5 ]. Cumulative saphenous vein graftocclusion rates in the first year after CABG surgery
are 10% to 15%
Consequently, by 10 years post-CABG, only 60% ofvein grafts remain patent, and only 50% of patent
grafts are free of significant stenosis
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Aspirin
Within the setting of CABG surgery, aspirin
exhibits a cardioprotective effect: when
started immediately postoperatively it
improves not only graft patency but also
patient survival
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Aspirin
Early and late saphenous vein graft patency
rates are improved by aspirin therapy ( 100
mg/day) initiated either on the day preceding
CABG surgery [ 17 ] or in the immediate
postoperative period (1 hour to 5 days after
surgery)
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The American College of Chest Physicians
currently recommends that aspirin (325
mg/day) should be initiated 6 hours after
CABG surgery and maintained for1 yearto
reduce the risk of saphenous vein bypass
graft closure
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initiation of aspirin in the first 48 hours after
CABG surgery has been reported to reduce
the risk of in-hospital mortality (68% lower)
and ischemic myocardial, cerebral, renal, and
intestinal complications ( 40% to 70% lower)
Aspirin use during this early postoperativeperiod was a significant predictor of in-
hospital survival
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Preoperative aspirin use
Preoperative aspirin use in CABG patients
appears to reduce the risk of perioperative
myocardial infarction and in-hospital mortality.
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patients undergoing isolated CABG (n =
8,641), aspirin administration within the 7-day
period immediately preceding surgery
reduced in-hospital mortality
in a prospective evaluation of 5,065 patients
undergoing CABG surgery, preoperative
discontinuation of aspirin was reported toincrease the risk of in-hospital mortality
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Bleeding Complications in CABG Surgery
Risk factors for postoperative bleeding andperioperative use of blood products aremultifactorial and include advanced age,
female gender, chronic renal disease,diabetes, low hematocrit, prolongedcardiopulmonary bypass time, reoperation,emergency operation, the proximity of
antiplatelet/thrombolytic therapy to CABGsurgery, and the use of anticoagulants duringthe CABG procedure
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Effect of aspirin on Post-CABG Bleeding
Numerous (predominantly older) studies have
reported that preoperative use (typically 2
days before surgery) of aspirin ( 75 mg/day)
increases blood loss, transfusion
requirements, and re-exploration rates for
bleeding in CABG patients
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Effect of aspirin on Post-CABG Bleeding
In contrast, more recent studies have
described no significant increase in bleeding
complications
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Importantly, perioperative transfusion
requirements have been found to depend on
the aspirin-free interval
requirements were confined to those who
discontinued aspirin less than 2 days before
surgery; patients who stopped aspirin 3 to 7days preoperatively had little or no increased
transfusion requirement
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Moreover, initiation of aspirin therapy in the
first 48 hours after CABG surgery did not
increase bleeding in the period before
hospital discharge
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serious bleeding was reported to be less
common with lower doses (75 to 162 mg/day)
than with higher doses (162 to 325 mg/day)
of aspirin (2.4% vs 3.3%)
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Comments
In this era of aggressive platelet inhibition for
treatment of coronary artery disease, the
optimal management of patients presenting
for CABG surgery while on oral antiplatelettherapy is still evolving
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New evidence suggests that oral antiplatelet
therapy can be used with relative safety
closer to the time of surgery than the
ACC/AHA guidelines recommend
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Although aspirin and clopidogrel use within 5
days of surgery can increase procedural
bleeding in high-risk patients, there is no
associated rise in perioperative mortality
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Since the risk of bleeding with aspirin is dose
dependent, it may be prudent to use a lower
dose of aspirin (75 to 100 mg) in the
preoperative period (and definitely in thepostoperative period)
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In summary, for the patient requiring urgent
or emergent CABG surgery, any risk of
bleeding associated with continuation of
antiplatelet therapy is likely to be greatlyoutweighed by its clinical benefit in
preventing further ischemic events in the
period before revascularization.
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Collaborative overview of randomised trials of antiplatelet therapy - II: Maintenance of
vascular graft or arterial patency by antiplatelet therapy
BMJ1994;308:159-168 (15 January)
This overview of trials ofantiplatelet therapy duringand after surgery suggests that the substantialbenefits of such therapy generally outweigh anyrisks of bleeding
Detailed analysis of bleeding complications in a trialofaspirin started preoperatively in patients havingcoronary artery bypass surgery found a small butsignificant increase in drainage from the chest tube,
in perioperative transfusion requirements, and in thereoperation rate, but there was no excess mortalitydue to bleeding complications
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Reference
Balancing the Benefit and Risk of OralAntiplatelet Agents in Coronary ArteryBypass SurgeryThe Annals of Thoracic Surgery Vol: 80Issue: 2, August, 2005
Effect of Preoperative Aspirin Use in Off-Pump Coronary Artery Bypass Operations
~Ann Thorac Surg 2003;76:415
Effe
ct of pre-oper
ative
aspiri
nuse o
nmortality incoronary artery bypass
grafting patients. Ann Thorac Surg 2000;70:198690.
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Improved graft patency in patients treated
with platelet-inhibiting therapy after coronary
bypass surgery, Circulation, Volume: 72, (1985), pp. 138--146
Immediate postoperative aspirin improves
graft patency early and late after coronary
artery bypass graft surgery, Circulation, Volume: 83, (1991),pp. 1526--1533