[Antithrombotic therapy in atrial fibrillation]

The known risk of embolic events in patients with recurrent or chronic atrial fibrillation makes it mandatory to recommend oral anticoagulation in patients with rheumatic mitral valve disease, specially mitral stenosis to maintain an INR between 2.0 and 3.0. If despite this treatment recurrent embolism occurs, the dose of oral anticoagulants should be increased (INR between 2.5 and 3.5) or dipyridamole (200 to 400 mg/day) or aspirin (160 to 320 mg/day) should be added to dicoumarinic drugs. In patients that must be cardioverted either electrically or pharmacologically and who have been on atrial fibrillation for more than 2 days, oral anticoagulation should be maintained for 3-4 weeks before cardioversion and for 3-4 weeks after regaining sinus rhythm. Transesophageal echocardiography may enable us to identify the group of patients with low risk for an immediate cardioversion. In patients under 60 years of age with atrial fibrillation and no evidence of associated cardiovascular abnormality (lone atrial fibrillation) the embolic risk is very low and antithrombotic therapy is probably not needed. In subjects over 60 years of age with a low risk profile (absence of previous stroke, heart failure or systemic hypertension) aspirin (300-325 mg a day) seems to offer sufficient protection against embolic events. In patients at a higher embolic risk (history of previous cerebral ischemic attacks, heart failure of left ventricular dysfunction, systemic hypertension) oral anticoagulation unless contraindicated, should be recommended (INR 2.0-3.0). The role of other antithrombotic agents such as ticlopidine or triflusal to prevent embolic events in patients with atrial fibrillation is unknown.