Objective: 

Slow coronary flow (SCF) is delayed progression of the contrast seen at the coronary angiography in the absence of epicardial stenosis and/or of other conditions associated with decreased coronary flow velocity. While microvascular abnormalities are suspected to underlie the mechanism of SCF, less attention has been paid to intrinsic properties of blood that can also impair microcirculatory flow. In this study we aimed to evaluate erythrocyte deformability, erythrocyte aggregation, whole blood and plasma viscosity in SCF.

Methods: 

Thirty patients with SCF (53.70 ±1.73 years, 11 male) and 20 subjects with normal coronary arteries (11 male, 54.05±2.69 years) were included in the study. Coronary flow was quantified by means of thrombolysis in myocardial infarction (TIMI) frame count. Aggregation and deformability of erythrocytes were measured by an ektacytometer. Viscosities were measured by a cone-plate viscometer. This study was approved by the local ethics committee. Independent samples t-test and Mann–Whitney U test were used for statistics.

Results: 

There was no statistically significant difference between the groups with respect to age, sex, family history, body mass index, fibrinogen levels, hematological parameters, diabetes, hypertension and smoking. Erythrocyte deformability measured at 0.30 Pascal (Pa) (0.040±0.003 vs. 0.048±0.002, respectively, p< 0.05); 0.53 Pa (0.056±0.003 vs. 0.070±0.004, respectively, p< 0.05); 0.95 Pa (0.114±0.007 vs. 0.138±0.006, respectively, p< 0.05); 1.69 Pa (0.205±0.009 vs. 0.330±0.007, respectively, p< 0.05); 3.00 Pa (0.305±0.009 vs. 0.330±0.007, respectively, p< 0.05) were higher in SCF patients. Erythrocyte aggregation parameters and viscosities were similar between the two groups.

Conclusions: 

Increments in erythrocyte deformability may serve as an advantageous factor to regulate blood flow in SCF.