Abstract
Introduction : Aspirin and clopidogrel are the most commonly
used antiplatelet agents, either alone or as dual therapy, in patients
undergoing CABG surgery to reduce organ ischaemia and mortality. The
systematic review aims to explore the resistance to the antiplatelet
agents, how to assess it, and the effect of resistance on the outcomes
in CABG surgery.
Materials & methods : A systematic search is carried out on
MEDLINE via Ovid, PubMed, Embase, the Cochrane Library Database and
Google Scholar until November 2021 to look for studies evaluating the
antiplatelet resistance in patients undergoing both on-pump and off-pump
CABG surgery. Only high-quality studies were included after the risk of
bias assessment.
Results : A total of 17 studies, of which 3 randomised
controlled trials and 14 observational studies were included after
inclusion criteria is applied. The incidence of aspirin resistance
ranges from 11-51.5%, whereas, clopidogrel resistance is 22%. A wide
variety of different assessment methods for antiplatelets are reported.
Antiplatelet resistance is a predictor of vein graft occlusion, with up
to 13 fold increase in occlusion rate. There is no overall effect of
aspirin resistance on mortality, stroke or myocardial infarction,
however, clopidogrel resistance leads to higher mortality, MI and target
vessel revascularisations. The effect of cardiopulmonary bypass on
antiplatelet resistance is not clear.
Conclusion : There is no uniform definition of antiplatelet
resistance. Assessment methods differ greatly and their results are not
interchangeable. Antiplatelet resistance is associated with a higher
rate of graft occlusion in CABG patients. Aspirin resistance does not
influence overall adverse outcomes, however, clopidogrel resistance
leads to worse outcomes.
Keywords : Antiplatelet resistance, Aspirin, Clopidogrel,
CABG, Coronary artery bypass grafting
ABBREVIATIONS:
ACS: Acute coronary syndrome
ADP: Adenosine diphosphate
ARU: Aspirin reaction unit
AUC: Arbitrary area under the curve
BMI: Body mass index
CABG: Coronary artery bypass grafting
CADP: Collagen/ADP coated apertured cartridges
CEPI: Collagen/epinephrine coated apertured cartridges
CPB: Cardiopulmonary bypass
MA: Maximum amplitude
MEA: Multiple electrode aggregometry
MI: Myocardial infarction
NOS: Newcastle-Ottawa Scale
PFA: Platelet function assay
PRISMA: Preferred Reporting Items for Systematic Reviews And
Meta-Analyses
PRP: Platelet-rich plasma
PRU: P2Y12 reaction unit
TEG: Thromboelastogram
TxA2: Thromboxane A2
TxB2: Thromboxane B2