Treatment with Aspirin and Dipyridamole is More Effective than Aspirin in Reducing Low Shear Blood Viscosity

Abstract

Investigate effects of aspirin/dipyridamole and aspirin on blood viscosity (BV) in subjects with hyperhomocystememia (>14 micromol/L) and stable cardiovascular disease (CVD) or >or= 20% risk for CVD were the aims of this study. Forty-seven subjects were treated with 14 days of either aspirin/dipyridamole (25 mg/200 mg twice-daily) or aspirin (81 mg daily). BV was measured from fasting specimens at 37 degrees C from whole blood at shear rates ranging from 1,000 to 1s(-1) by using a scanning capillary viscometer (Rheolog; Rheologics Inc., Exton, Pennsylvania, USA). Aspirin/dipyridamole was more effective than aspirin therapy in reducing BV at shear rates of 1 s(-1) (-3.03 [-3.88, -2.17] mPas vs. -0.07 [-1.06, 0.92] mPas; P<0.0001) and 2 s(-1) (-1.86 [-2.72, -1.01] mPas vs. -0.21 [-1.20, 0.79] mPas; P=0.0136); however, there were no significant differences in blood viscosity at shear rates of 5 s(-1) to 1000 s(-1). Changes in hematocrit, a major determinant of whole BV, were greater in the aspirin/dipyridamole group than the aspirin group (P=0.043). After hematocrit adjustment, differences in BV between aspirin/dipyridamole and aspirin remained significant at 1s(-1) (-2.78 [-3.68, -1.88] mPas vs. -0.04 [-1.05, 0.98] mPas; P<0.0001) and 2 s(-1) (-1.62 [-2.52, -0.72] mPas vs. -0.17 [-1.19, 0.85] mPas; P=0.0315). These findings may have important clinical benefits in the CVD prevention and treatment due to the contribution of BV in tissue perfusion and thrombus formation.