1. INTRODUCTION
Aspirin and clopidogrel are the two most commonly used antiplatelets in
patients undergoing coronary artery bypass grafting (CABG) surgery.
Aspirin is administered early after CABG to reduce the risk of death and
organ ischaemia of the heart, brain, kidneys and gastrointestinal
tract.1 The early administration of aspirin after CABG
surgery also has significantly improved the patency of vein grafts
without increasing the risk of bleeding.2 Aspirin
inhibits the transformation of arachidonic acid into thromboxane A2
(TxA2) by irreversibly acetylating the platelet cyclooxygenase (COX)
enzyme. Due to its chemical instability, TxA2 is then converted to
stable and inactive thromboxane B2 (TxB2), and its metabolite
11-dehydroTxB2, which can be detected in the urine.
Dual antiplatelet therapy with aspirin and clopidogrel is associated
with a reduced risk of thrombotic complications following acute coronary
syndrome (ACS).3 Clopidogrel is adenosine diphosphate
(ADP) receptor antagonist that irreversibly inhibits by binding to the
platelet P2Y12 receptor. Dual antiplatelet therapy leads to reduced
all-cause mortality and improved vein graft patency, and their effects
are more significant in patients with ACS undergoing CABG
surgery.4,5
Antiplatelet resistance in some patients has been linked to early graft
failure and identified to be due to the poor responsiveness of these
groups of patients to the administered antiplatelet
agents.6 A variety of tests are available for the
assessment of antiplatelet resistance, however, these tests are neither
equally precise nor correlate among themselves.7 The
systematic review aims to explore the current practice, application of
assessment methods and the effects of antiplatelet resistance in
patients undergoing CABG surgery.