Balancing the Benefit and Risk of Oral Antiplatelet Agents in Coronary Artery Bypass Surgery The Annals of Thoracic Surgery Vol: 80 Issue: 2, August, 2005 By Intern ???/P???

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Balancing the Benefit and Risk of Oral
Antiplatelet Agents in Coronary Artery Bypass
Surgery The Annals of Thoracic Surgery
Vol 80 Issue 2 August 2005
By Intern
/ P

2

• 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
  and platelets and initiation of intravascular
  thrombosis

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Benefits of Oral Antiplatelet Therapy in CABG
Surgery

• the mainstay of primary and secondary prevention
  in atherothrombotic disease
• broad consensus about the value of long-term
  aspirin therapy in reducing the risk of death
  myocardial infarction and stroke in patients at
  high risk of occlusive vascular disease 8 as
  well as in preventing ischemic complications 9
  and maintaining early and late vein-graft
  patency after CABG

4

• Aortocoronary grafts are susceptible to acute
  thrombotic occlusion during the first month after
  CABG surgery and subsequently to
  atherosclerotic obstruction 5 . Cumulative
  saphenous vein graft occlusion rates in the first
  year after CABG surgery are 10 to 15
• Consequently by 10 years post-CABG only 60 of
  vein grafts remain patent and only 50 of patent
  grafts are free of significant stenosis

5
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)

7

• The American College of Chest Physicians
  currently recommends that aspirin (325 mg/day)
  should be initiated 6 hours after CABG surgery
  and maintained for 1 year to reduce the risk of
  saphenous vein bypass graft closure

8

• 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 postoperative
  period was a significant predictor of in-hospital
  survival

9
Preoperative aspirin use

• Preoperative aspirin use in CABG patients appears
  to reduce the risk of perioperative myocardial
  infarction and in-hospital mortality.

10

• patients undergoing isolated CABG (n 8641)
  aspirin administration within the 7-day period
  immediately preceding surgery reduced in-hospital
  mortality
• in a prospective evaluation of 5065 patients
  undergoing CABG surgery preoperative
  discontinuation of aspirin was reported to
  increase the risk of in-hospital mortality

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Bleeding Complications in CABG Surgery

• Risk factors for postoperative bleeding and
  perioperative use of blood products are
  multifactorial and include advanced age female
  gender chronic renal disease diabetes low
  hematocrit prolonged cardiopulmonary bypass
  time reoperation emergency operation the
  proximity of antiplatelet/thrombolytic therapy to
  CABG surgery and the use of anticoagulants
  during the 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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(No Transcript)
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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 7 days
  preoperatively had little or no increased
  transfusion requirement

16

• Moreover initiation of aspirin therapy in the
  first 48 hours after CABG surgery did not
  increase bleeding in the period before hospital
  discharge

17

• 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 antiplatelet therapy is
  still evolving

19

• 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

20

• 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

21

• 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 the postoperative
  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 greatly outweighed by its
  clinical benefit in preventing further ischemic
  events in the period before revascularization.

23
Collaborative overview of randomised trials of
antiplatelet therapy - II Maintenance of
vascular graft or arterial patency by
antiplatelet therapy BMJ 1994308159-168
(15 January)

• This overview of trials of antiplatelet therapy
  during and after surgery suggests that the
  substantial benefits of such therapy generally
  outweigh any risks of bleeding
• Detailed analysis of bleeding complications in a
  trial of aspirin started preoperatively in
  patients having coronary artery bypass surgery
  found a small but significant increase in
  drainage from the chest tube in perioperative
  transfusion requirements and in the reoperation
  rate but there was no excess mortality due to
  bleeding complications

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Reference

• Balancing the Benefit and Risk of Oral
  Antiplatelet Agents in Coronary Artery Bypass
  Surgery
  The Annals of Thoracic Surgery
  Vol 80 Issue 2 August 2005
• Effect of Preoperative Aspirin Use in Off-Pump
  Coronary Artery Bypass Operations
• Ann Thorac Surg 200376415
• Effect of pre-operative aspirin use on mortality
  in coronary artery bypass grafting patients. Ann
  Thorac Surg 200070198690.

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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