Summary
Despite conflicting clinical evidence on higher HbA1c as prognostic
marker of poor outcomes post-cardiac surgery, there is universal
consensus of possible underlying mechanism of association. Therefore,
future research to further elucidate any possible clinical association
is warranted. Such research has the potential to improve perioperative
cardiac surgery clinical practice guidelines.
HbA1c have significant role in inducing dyslipidaemia,
hyperhomocysteinemia, hypertension and increasing C-reactive protein,
oxidative stress, and blood viscosity 56. Cardiac
surgery, stress, and anaesthesia can exacerbate oxidative stress and
increase blood viscosity, thereby perpetuating the effect of high HbA1c
in patients with diabetes and likelihood of devolvement of
cardiovascular event 57. Increased blood viscosity of
diabetic patients, leading to blood clots, which can precipitate acute
MI 58. Moreover, high HbA1c can cause vascular
endothelial cell damage, due to blood flow shear stress, with increased
cellular proliferation 59–62, which can cause MI and
stroke after coronary artery stenting 63. Chronic
hyperglycaemia-induced dysmetabolism, weakens chemokine chemotaxis and
decreases immune function in patients with diabetes64. This increases likelihood of wound infection
post-cardiac surgery and increases collateral tissue damage upon
infection. For these reasons, high preoperative HbA1c levels may be
predictive of a prolonged postoperative hospital stay.