Atrial fibrillation and cardioembolic stroke.

The most disabling consequence of atrial fibrillation (AF) is stroke. In the elderly, AF is the single most important cause of stroke. The risk of stroke is increased at least 6-fold in subjects with AF. Strokes in patients with AF are in general severe, associated with higher risk of fatality and prone to early and long-term recurrence. The cardiac origin of stroke can be strongly suspected by anamnesis, clinical examination and findings on neuroimaging. Paroxysmal AF is an important cause of brain embolism, that is often difficult to document. Risk factors for stroke in AF include: previous embolism (including previous transient ischaemic attack (TIA), or ischaemic stroke), age >65 years, structural cardiac disease, rheumatic or other significant valvular heart disease, valvular artificial prosthesis, hypertension, heart failure and significant left ventricular systolic dysfunction, diabetes and coronary disease. All AF patients with TIA or stroke have a formal indication for long-term anticoagulation. Only patients without risk factors or with contraindications to warfarin should be put on aspirin. Treating 1 000 patients with AF for 1 year with oral anticoagulants rather than aspirin would prevent 23 ischaemic strokes while causing 9 major bleedings. Despite its enormous preventive potential, oral anticoagulants are underused in AF, because treating physicians often have lack of knowledge about trials and guidelines, underestimate the benefits and overestimate the risks associated with continuous oral anticoagulation. The introduction of anticoagulants that do not need frequent control tests, such as ximelagatran, will increase the proportion of AF patients with risk factors for stroke who are anticoagulated. There is no evidence to support routine immediate anticoagulation in acute ischeamic stroke associated with AF.