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.