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.