Puneet Kakar

Atrial fibrillation—the growing epidemic

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Hypertension: endothelial dysfunction, the prothrombotic state and antithrombotic therapy

The pathophysiology of essential hypertension and its complications has been a focus of much research and clinical interest. More recent attention has been directed towards inflammation and endothelial dysfunction, especially since inflammation can promote endothelial dysfunction and the latter has been intimately related to thrombogenesis and atherogenesis. Hypertension is also associated with a prothrombotic or hypercoagulable state, and this may contribute to the observation that despite the blood vessels being exposed to high pressures in hypertension the common complications of the latter are paradoxically thrombotic rather than hemorrhagic – the so-called ‘thrombotic paradox of hypertension’ (or ‘Birmingham paradox’). Despite these thrombotic complications, the role of antithrombotic therapy for primary prevention in hypertension is less defined, unless the patient is at significant risk of cardiovascular events or has renal impairment. Antithrombotic therapy for secondary prevention in hypertension is recommended, but unanswered questions regarding the interactions between aspirin and angiotensin-converting enzyme inhibitors remain.

Atrial fibrillation and stroke prevention

There is overwhelming evidence from randomized trials and systematic reviews to indicate the benefit of thromboprophylaxis in patients with atrial fibrillation. In moderate- to high-risk subjects, oral anticoagulation with warfarin reduces stroke by two-thirds, while aspirin reduces stroke by 22%. The latter result is similar to that seen for stroke reduction with antiplatelet therapy in vascular disease. Numerous studies have shown that less than half the patients eligible for warfarin therapy actually receive it and under- or overanticoagulation is common. This leads to many missed opportunities in optimizing stroke prevention in atrial fibrillation. The limitations of existing oral anticoagulants have resulted in the development of many new drugs. The aim of this review is to provide a brief overview of thromboprophylaxis in atrial fibrillation, and the opportunities for improvement in the provision made for thromboprophylaxis.