The Effects of Antihypertensive Therapy on Haemostatic Parameters

There is extensive trial-based evidence showing that antihypertensive drugs reduce the risk of vascular events (e.g. stroke and myocardial infarction) as well as target organ damage (e.g. left ventricular hypertrophy and microalbuminuria). However, some of these benefits appear to be, at least partially, independent of the extent of blood pressure (BP) lowering. It is also evident that in certain clinical situations some antihypertensive drugs are more effective than others. In this review we discuss the effects of antihypertensive drugs on the endothelium, platelets, fibrinolysis and coagulation. These properties may account for the observed BP-independent actions. Antihypertensive drugs exert multiple effects on the vascular endothelium. These include effects on nitric oxide (NO) and angiotensin II-mediated actions. Many BP lowering drugs can inhibit platelet activity, although the relevance of this property is unknown, especially if patients are also taking platelet inhibitors (e.g. aspirin). Antihypertensive drugs also influence fibrinolysis and coagulation. These effects may be mediated by a variety of mechanisms, including altering insulin sensitivity. The haemostatic actions of antihypertensive drugs deserve greater recognition and further investigation.