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Arch Hellen Med, 22(5), September-October 2005, 467-484


Prevention of thromboembolic events in atrial fibrillation

Transfusion Service, "KAT" General Hospital, Athens, Greece

Atrial fibrillation (AF) is the most common arrhythmia of clinical importance, and is associated with increased risk of cardiovascular morbidity and mortality. The prevalence in the general population is 1% and increases with age from 0.5% in patients below 59 years of age to more than 5% in patients over 70 years. With an increasingly elderly population, AF is likely to become more common and to constitute a significant public health problem. Atrial fibrillation is associated with a substantial risk of thromboembolic events of which ischemic stroke is clinically the most important. Ischemic strokes are generally more severe in patients with AF than in patients with sinus rhythm, they are more likely to be fatal, and among survivors recurrence of stroke is more frequent and neurological deficits more severe. Over the past decade, great advances have been made in stroke prevention, among the most potent of which is the use of anticoagulation therapy for patients with AF. Oral anticoagulation therapy (OAC) with antivitamin K is effective in reducing ischemic stroke by 68% in patients with non-valvular AF, and by even more in patients with valvular AF. The relative lack of success in the treatment and prevention of this arrhythmia, which has been recognised for over 100 years, may be due to incomplete understanding of its pathophysiology and the risk factors which precipitate its occurrence. OAC therapy is recommended particularly if additional risk factors for stroke or embolism are present, such as age >65 years, arterial hypertension, diabetes, and previous stroke. Nevertheless, OAC is still underused and only a quarter to a half of patients who have AF, with or without additional risk factors for stroke, are actually given anticoagulants. Numerous barriers to the use of dose-adjusted antivitamin K exist, which are practical, patient-, physician-, and healthcare system-related. These include the complex pharmacokinetics of antivitamin K, the need for continuous prothrombin time monitoring and dose adjustments, bleeding events, noncompliance, drug interactions, and the increased costs of monitoring and therapy. Possible solutions to these problems include improved education of patient and physician, the institution of anticoagulation clinics and the use of newer pharmacological and non-pharmacological therapies that are rapidly being developed.

Key words: Arrhythmia, Atrial fibrillation, Oral anticoagulation therapy, Prevention, Risk factors, Ximelagatran.

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