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Atrial fibrillation. Thromboembolic risk and indications for anticoagulation
1Division of General Internal Medicine, University of Washington School of Medicine, Seattle.
Insights
Patients with atrial fibrillation face high stroke risks, especially with rheumatic mitral valve disease. Anticoagulation is crucial for preventing strokes in most patients, balancing bleeding risks with significant benefits.
Area of Science:
- Cardiology
- Neurology
- Pharmacology
Background:
- Atrial fibrillation significantly elevates embolic stroke risk, influenced by underlying cardiac conditions.
- Stroke risk varies with atrial fibrillation type (chronic vs. paroxysmal) and patient demographics.
- Rheumatic mitral valve disease presents the highest stroke risk among atrial fibrillation etiologies.
Purpose of the Study:
- To analyze stroke risk factors in patients with atrial fibrillation.
- To evaluate the efficacy and risks of anticoagulation therapy for stroke prevention.
- To inform clinical decisions regarding anticoagulation in diverse atrial fibrillation patient groups.
Main Methods:
- Review of epidemiological data on stroke incidence in atrial fibrillation.
- Analysis of clinical outcomes associated with anticoagulation therapy.
- Risk-benefit assessment of anticoagulation based on arrhythmia cause and patient profile.
Main Results:
- Atrial fibrillation with rheumatic mitral valve disease confers a 17-fold increased stroke risk.
- Nonvalvular heart disease increases stroke risk fivefold; chronic AF poses higher risk than paroxysmal.
- Major bleeding occurs in 5-10% of patients on anticoagulation.
Conclusions:
- Anticoagulation is effective in preventing primary and recurrent strokes in most patients with atrial fibrillation, including those with valvular and nonvalvular heart disease.
- Treatment decisions require careful consideration of arrhythmia etiology, cardiovascular comorbidities, and individual bleeding risk.
- Evidence supports the widespread use of anticoagulation for stroke risk reduction in atrial fibrillation.
Abstract:
The risk of embolic stroke in patients with atrial fibrillation is largely related to the underlying disorders responsible for the arrhythmia. Atrial fibrillation associated with rheumatic mitral valve disease has the highest stroke risk (about 17 times greater than unaffected controls), but even with nonvalvular heart disease, the risk is increased fivefold. The stroke risk is greater with chronic than with paroxysmal atrial fibrillation, is highest in the year after onset of the arrhythmia, and is lower in younger patients with idiopathic ("lone") atrial fibrillation. Major bleeding episodes, the most important risk of anticoagulation, occur in about 5% to 10% of patients. The decision to anticoagulate a patient with atrial fibrillation depends on the cause of the arrhythmia, especially any associated cardiovascular disease, and the individual's risk from anticoagulation. Growing evidence supports the effectiveness of anticoagulation of most patients with nonvalvular, as well as valvular, cardiac disease for the prevention of both primary and recurrent strokes.