Blood rheology and RBC aggregation in patients with angina pectoris and a prior history of myocardial infarction

Several rheological variables were examined in 15 patients with stable or unstable angina pectoris and a prior history of myocardial infarction (MI); the mean time since MI was 42.1 ± 70.9 months (range = 2–263 months, median = 10.2 months). Rheologic parameters measured included: hematocrit, whole blood viscosity (750 and 1500 s⁻¹), plasma viscosity, degree of RBC aggregation (ZSR), extent and rate of RBC aggregation following stasis (Myrenne Aggregometer). Compared to normal control donors, the pooled patient data indicated: 1) no significant difference in hematocrit; 2) a significant increase of plasma viscosity (13%); 3) significant increases in blood viscosity at both shear rates (13% and 17%, respectively); 4) significant increases in the degree (23%), the extent (27%) and the rate (33% faster time constant) of RBC aggregation; 5) significant elevations of gamma globulin (51%), fibrinogen (46%) and alpha-2 (25%) concentrations which correlated with the enhanced RBC aggregation; 6) no significant correlations between either the rheologic or hematologic parameters and the time since MI. Rheologic abnormalities were evident when patients with stable or unstable angina were compared with controls, but only plasma viscosity and RBC aggregation time constant differed between the subgroups. Post-MI patients with angina pectoris thus exhibit marked rheological abnormalities which are compatible with altered blood flow dynamics and which represent potential risk factors for further circulatory complications.