Should patients with hypertension receive antithrombotic therapy?

The main complications of hypertension, i.e. coronary heart disease, ischaemic strokes and peripheral vascular disease (PVD), are usually related to thrombosis. Increasing evidence also suggests that hypertension fulfils the components of Virchow's triad, thus conferring a prothrombotic or hypercoagulable state, as evident by abnormalities of haemostasis, platelets and endothelial function. It therefore seems plausible that use of antithrombotic therapy may help prevent these thrombosis-related complications of hypertension. Indeed, hypertensive patients with an estimated 10-year CHD risk > or = 15% will have their cardiovascular risk reduced by 25% using antihypertensive treatment, but the addition of aspirin further reduces major cardiovascular events by 15%. Recent guidelines recommend the use of aspirin 75 mg daily for hypertensive patients who have no contraindication to aspirin, in one of the following categories: (i) secondary prevention - cardiovascular complications (myocardial infarction, angina, non-haemorrhagic stroke, peripheral vascular disease or atherosclerotic renovascular disease); and (ii) primary prevention - those with blood pressure controlled to < 150/90 mmHg and one of: (a) age > or = 50 years and target organ damage (e.g. LVH, renal impairment, or proteinuria); (b) a 10-year CHD risk > or = 15%; or (c) type II diabetes mellitus. However, some of the risks of aspirin administration, namely increased incidence of major bleeding events, may possibly outweigh the benefits, especially in low-risk individuals.