The effects of angiotensin II signaling blockade on platelet activity in subjects with hypertension.

Abstract

To investigate the effects of Angiotensin II receptor blockade (ARB) and angiotensin converting enzyme (ACE) inhibition on platelet reactivity in patients with mild to moderate hypertension. PFA-100 evaluates platelet function (expressed in seconds as closure time, CT) in anti-coagulated whole blood in vitro at high shear rates. The test cartridge is impregnated with either collagen and epinephrine (Col/Epi) or collagen and ADP (Col/ADP). 33 patients were randomized to perindopril 4mg (n = 9), valsartan 80mg/d (n = 9) and for lifestyle modification (n = 15) for 4 weeks. Platelet reactivity was measured at baseline and after 4 weeks by PFA-100. Normotensive controls (n = 11) were also tested at baseline to standardize PFA-100 CT. Haematocrit, platelet count and plasma vWF antigen levels were measured. There was no difference in baseline haematocrit, platelet count or vWF antigen level between the groups. The vWF antigen levels measured after 4 weeks showed no significant difference either. Significant blood pressure reduction was seen in the treated group (SBP P = 0.002 and DBP P = 0.005) when compared to the life style modification group (SBP P = 0.06 and DBP P = 0.04) after 4 weeks. There was no significant statistical difference in Col/ADP CT in treated and non-treated groups but increase in CT (P = 0.05) in treated group with Col/Epi seen after 4 weeks. In patients with mild to moderate hypertension, valsartan and perindopril compared to life style modification demonstrate a significant decrease in platelet reactivity.