Effect of clinical and RBC hemorheological parameters on myocardial perfusion in patients with type 2 diabetes mellitus

Myocardial ischemia may be present even when there is no significant stenosis of the epicardial coronary artery, or after coronary angioplasty for significant coronary artery disease. This phenomenon is related to disturbance of the coronary microcirculation or vasomotor tone. The aim of this study was to determine the influence of clinical and RBC hemorheological factors, such as RBC deformability and aggregation, on myocardial perfusion in patients with type 2 diabetes mellitus (DM) when compared to patients without DM, presenting with stable angina or acute coronary syndrome. Myocardial perfusion was graded using the myocardial blush grade (MBG) which describes the relative 'blush' or intensity of the radio-opacity of myocardial tissue observed after an epicardial coronary injection of contrast medium during coronary angiography. MBG was counted before any medical or mechanical intervention, and in the myocardial territory without anatomical flow limitation (<50% of luminal narrowing on coronary angiogram), in order to remove the direct influence of anatomical stenosis. Myocardial perfusion in this region was associated with diabetes, renal function, LV diastolic function, inflammatory biomarkers such as hs-CRP, fibrinogen and ESR, but not with the clinical presentation. Among the hemorheological parameters, reduced myocardial perfusion was linked to increased RBC aggregation, but not to variation in RBC deformability. In conclusion, myocardial perfusion was affected by diabetes, left ventricular diastolic function, and inflammatory activity indicated by clinical parameters, and by the hemorheological factor RBC aggregation.