Relationship Between Level of Hemoglobin A1c and Platelet Function in Patients Undergoing Cardiac Surgery

Relationship Between Level of Glycosylated Hemoglobin and Platelet Function in Patients Undergoing Coronary Artery Bypass Grafting

The aim of this study is to evaluate whether increased level of hemoglobin A1c (HbA1c) correlates to higher level of platelet reactivity assessed by impedance aggregometry in patients with diabetes mellitus undergoing elective coronary artery bypass grafting (CABG).

This study will be conducted at Cardiac Surgery Department, University Hospital Center Zagreb. It will be conducted in prospective observational fashion. Diabetic patients undergoing isolated, primary on-pump CABG will be consecutively recruited. Patients requiring urgent procedure will be excluded. Blood samples, both for conventional lab. findings (including HbA1c) and impedance aggregometry will be drawn prior to surgery and postoperatively on daily basis.

Cohort sample will be divided into two subgroups according to HbA1c level (Group 1 with HbA1c < 7% and Group 2 with HbA1c ≥ 7%, respectively). Respective subgroups will be compared for basic demographic data, laboratory findings including those obtained using platelet function testing, and for clinical outcomes, respectively.

Multiple-electrode aggregometry:

Whole blood aggregation will be determined using a new-generation impedance aggregometer (Multiplate analyzer; Roche Diagnostics). In brief, when platelets expose receptors on their surface they get activated and stick on the Multiplate sensor wires enhancing the electrical resistance between them. An increase in impedance is expressed in arbitrary area under the curve (AUC) units. Platelet aggregation is determined in response to stimulation with arachidonic acid (ASPI (aspirin-sensitive patients identification) test designed to evaluate the effect to acetylsalicylic acid (ASA)) and adenosine diphosphate (ADP) (ADP test designed to evaluate the effect of thienopyridines, such as clopidogrel).

Inclusion Criteria:

• Patients undergoing isolated primary on-pump CABG
• Elective surgery
• Diabetic patients including insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus NIDDM
• Patients on antiplatelet therapy (aspirin and/or clopidogrel) pre- and postoperatively

Exclusion Criteria:

• Missing consent
• Patients with cardiac surgical procedures other than isolated CABG
• Patients on antiplatelet therapy other than aspirin or clopidogrel
• Urgent surgery
• Off-pump CABG
• Redo CABG