Relationship of homocysteine to markers of platelet and endothelial activation in 'high risk' hypertensives: a substudy of the Anglo-Scandinavian Cardiac Outcomes Trial

Abstract

<h2>Abstract</h2> <i>Objective</i>: To examine the relationship between plasma homocysteine (HCY) and rheological, endothelial and platelet markers in ‘high risk' hypertensive patients. <i>Design</i>: Cross-sectional study. <i>Subjects and Methods</i>: A total of 165 consecutive hypertensive patients (136 male; mean age 63 years (S.D. 8)) at high risk of cardiovascular disease who screened for inclusion in the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT) were studied along with 38 population normotensive healthy controls. We measured levels of plasma homocysteine [high pressure liquid chromatography (HPLC)], soluble P-selectin, a marker of platelet function, von Willebrand factor (vWF), an index of endothelial damage/dysfunction [both by ELISA] and fibrinogen (CLAUSS). The Framingham cardiovascular and cerebrovascular risk scores were calculated. <i>Results</i>: Hypertensives had significantly higher blood pressure (BP) [165/90(16/10) vs. 138/82(12/8) mm Hg, <i>p</i><0.0001], sP-sel [54(44–67) vs. 45(35–57) ng/ml, <i>p</i>=0.002], vWF [133(34) vs. 110(28) IU/dl, <i>p</i><0.0001], and fibrinogen [2.98(2.52–3.47) vs. 2.43(2.20–2.83)g/l, <i>p</i>=<0.0001]. Homocysteine were lower in our hypertensives compared with controls [8.7(6.9–11.2) vs. 10.5(8.5–13.1) μmol/l, <i>p</i>=0.005], but there were significant correlations between homocysteine levels and both calculated 10-year coronary heart disease risk (Spearman <i>r</i>=0.197, <i>p</i>=0.026) and stroke risk (<i>r</i>=0.210, <i>p</i>=0.018), using the Framingham equation. There was a positive correlation between plasma homocysteine and soluble P-selectin (<i>r</i>=0.180, <i>p</i>=0.025), which persisted in multiple linear regression analysis. There was no significant relationship between homocysteine and HCT, PV, or the endothelial marker, vWF. <i>Conclusion</i>: Hypertensives demonstrate abnormalities of endothelial, platelet and rheological function. Homocysteine is related to both 10-year coronary heart disease risk and stroke risk, and is significantly correlated with soluble P-selectin, a marker of platelet activation, in hypertensives but only weakly or not at all to other thrombotic markers. Increased platelet activation as reflected by soluble P-selectin may be one mechanism by which hyperhomocysteinaemia confers an increased thrombotic risk in hypertension.