Long-term outcome after stroke due to atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia. AF is paroxysmal or persistent and becomes permanent when it does not convert to sinus rhythm spontaneously or when attempted cardioversion fails. The prevalence of AF is 0.4% in the general population and increases with age up to 6-8% in octogenarians. In men, the age-adjusted prevalence is generally higher than in women. During AF, synchronous mechanical atrial activity is disturbed, resulting in haemodynamic impairment. This can give rise to thrombus formation and embolism to the systemic circulation. Thrombus associated with AF arises most frequently in the left atrial appendage. Cerebrovascular emboli in AF patients most often manifest as transient ischaemic attacks or ischaemic strokes. The overall rate of ischaemic stroke among patients with nonrheumatic AF averages 5% per year, but the rate increases with age. Patients with AF are at higher risk of cerebrovascular events from all causes. Of all strokes, one in every six occurs in patients with AF. Including transient ischaemic attacks and silent strokes detected radiographically, the overall rate of all cerebrovascular events in AF patients rises to more than 7% per year, although approximately one third of these are due to causes that are only secondarily or incidentally associated with AF or related anticoagulant therapy. Antiarrhythmic therapy is useful to improve cardiac rate and function in AF. However, to reduce first or recurrent emboli, antithrombotic therapy is of paramount importance. Results from several randomized clinical trials of antithrombotic therapies have shown that adjusted-dose warfarin reduces first or recurrent stroke by about 60% compared with placebo. When patients with nonvalvular AF are anticoagulated, the odds against ischaemic stroke and intracranial bleeding favour an INR between 2.0 and 3.0. Acetylsalicylic acid is less efficacious than warfarin in AF patients, reducing the risk of stroke by about 20%. Therefore, this antiplatelet agent should be used only for AF patients at low risk. Anticoagulation is the current treatment modality in AF patients at high or intermediate risk, i.e. patients with history of transient ischaemic attack or stroke, those aged >65 years, those with a history of hypertension, diabetes, heart failure or structural heart disease, valvular disease or significant systolic dysfunction. The benefit of dual antiplatelet regimens in AF patients is unknown, and combining antiplatelet agents with different mechanisms of action is an important topic for future investigation.