THE EFFECT OF ANTIHYPERTENSIVE DRUGS ON INVIVO PLATELET ACTIVITY IN ESSENTIAL-HYPERTENSION

Objective: To investigate whether antihypertensive drugs have a beneficial effect upon the abnormal in vivo platelet function found in patients with essential hypertension. Design: A cross-sectional study in which plasma beta-thromboglobulin, a marker of in vivo platelet activation, was measured in patients with essential hypertension on various antihypertensive drugs. All were free from any other diseases which might affect platelet function. Methods: Plasma beta-thromboglobulin was measured in 24 patients with untreated essential hypertension, 21 normotensive control patients, 16 patients receiving angiotensin converting enzyme (ACE) inhibitors, 16 patients receiving a beta-adrenoceptor blocker, 12 patients receiving calcium antagonists and 12 patients receiving a diuretic alone. Results: Untreated hypertensives had significantly elevated plasma beta-thromboglobulin levels compared with controls. Plasma beta-thromboglobulin levels in patients receiving beta-blockers and diuretics were not significantly different from untreated hypertensives. Treatment with calcium antagonists was associated with lower plasma beta-thromboglobulin levels, but this difference was not statistically significant. In contrast, treatment with ACE inhibitors was associated with significantly lower plasma beta-thromboglobulin levels compared with untreated hypertensives. Conclusion: These results suggest that antihypertensive drugs have different effects upon abnormal in vivo platelet function in patients with essential hypertension. The apparent beneficial effect of ACE inhibitors may mean that they have more impact than other drug groups in the prevention of coronary heart disease.