Balancing the Benefit and Risk of Oral Antiplatelet Agents in Coronary Artery Bypass Surgery

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

Balancing the Benefit and Risk of Oral Antiplatelet Agents in Coronary Artery Bypass Surgery

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