When
warfarin was the mainstay of anticoagulation for the prevention of
cardioembolic stroke, the paradigm was essentially "we mustn't anticoagulate anyone unless we prove that the
stroke was cardioembolic." Now that
direct-acting oral anticoagulants are available, the paradigm should change. The risk of
stroke is highest soon after the initial event, particularly in patients with more than one
infarction.
Direct-acting oral anticoagulants are not significantly more likely than
aspirin to cause severe
hemorrhage, and it is now clear that patients with
paradoxical embolism are better treated with
anticoagulant than
aspirin. Percutaneous closure of a
patent foramen ovale is better than
aspirin, but not better than
anticoagulant, and some patients with
paradoxical embolism may be better treated with
anticoagulant than with percutaneous closure, which cannot prevent
pulmonary embolism. Patients in whom
cardioembolic stroke is strongly suspected should probably be anticoagulated pending the results of investigations such as echocardiography and prolonged cardiac monitoring for
atrial fibrillation, and some of them, in whom the suspicion of a cardioembolic source is very strong, should probably be anticoagulated long term, even if such investigations do not confirm a cardiac source.