40 How soon before cardiac surgery should
aspirin be stopped?
Jonathan Unsworth-White
Aspirin irreversibly inhibits platelet function by blocking the
cyclooxygenase pathway. It is a vital adjunct in the prevention of
coronary thrombosis^1 and is known to reduce the risk of acute
bypass graft closure.^2 Unfortunately it also causes increased
bleeding after cardiac surgery and increases the risk of emergency
re-sternotomy in the first few hours.^3 For this reason many centres
try to stop aspirin for a few days prior to surgery.
Platelets have a life span in the plasma of approximately 10 days.
Therefore if aspirin were discontinued 10 days prior to surgery, the
affected platelet pool would be completely replenished with fresh
platelets by the time of the operation. This however leaves the
patient vulnerable to an acute myocardial event during the latter
part of this time and may also make graft occlusion more likely in
the immediate postoperative period. It also supposes that
operating lists can be planned 10 days in advance.
In reality, patients are usually asked to stop aspirin 5–7 days in
advance. This seems to be a suitable compromise for the majority
of patients although for a few (tight left main stem stenosis or past
history of TIAs or stroke), the risk of stopping aspirin may
outweigh the potential benefits.
RReeffeerreenncceess
1 Antiplatelet Trialists’ Collaboration. Collaborative overview of
randomised trials of antiplatelet therapy-1: Prevention of death,
myocardial infarction, and stroke by prolonged antiplatelet therapy in
various categories of patients.BMJ1994; 330088 : 81–106.
2 Antiplatelet Trialists’ Collaboration. Collaborative overview of
randomised trials of antiplatelet therapy-II: Maintenance of vascular
graft or arterial patency by antiplatelet therapy.BMJ1994; 330088 : 159–68.
3 Kallis P, Tooze JA, Talbot S,et al. Pre-operative aspirin decreases
platelet aggregation and increases post-operative blood loss – a
prospective, randomised, placebo controlled, double-blind clinical
trial in 100 patients with chronic stable angina.Eur J Cardio-thorac Surg
1994; 88 : 404–9.