Antithrombotic Therapy: Standard Therapy in Essential Hypertension?

Abstract

From the University Department of Medicine, City Hospital, Birmingham, England, UK. Address reprint requests to Gregory Y.H. Lip, MD, FRCP, Professor, University Department of Medicine, City Hospital, B18 7QH Birmingham, England, UK. E-mail: g.y.h.lip@bham.ac.uk 0033-0620/$ see front matter n 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.pcad.2006.03.004 The most devastating manifestations of btarget organ damageQ in hypertension are stroke and myocardial infarction (MI), and these complications are more related to occlusive thrombus formation, despite the blood vessels in hypertension being exposed to high pressures. The apparent paradox—that blood vessels in hypertension thrombose, and not burst, because of the high pressures—was first described in 1994 and has since been referred to as the bthrombotic paradox of hypertensionQ (or the bBirmingham paradoxQ or sometimes the bLipBeevers paradoxQ). Since 1994, substantial advances have progressed in relation to elucidating the underlying pathophysiology of the prothrombotic state associated with hypertension and the mechanisms leading to this increased tendency to thrombosis. Epidemiologically, the presence of hypertension increases the influence of stroke and MI with a near dose-response relationship, with the highest risk noted at the highest blood pressures (BPs). Conversely, lowering BP by antihypertensive therapy significantly lowers this risk. Despite efforts to lower BP, many patients still remain at risk, and in view of the thrombotic nature of the complications concerned, the possibility that antithrombotic therapy may further reduce complications associated with hypertension seemed plausible, given the underlying pathophysiological conditions leading to a prothrombotic state. It should be noted that antithrombotic therapy is advocated for many of the medical conditions commonly associated with hypertension, such as atrial fibrillation (AF) and vascular disease (whether carotid, coronary or peripheral artery disease). In AF, for example, hypertension is one of the commonest predisposing factors, and the