Stroke prevention in non-rheumatic atrial fibrillation.

Warfarin can strikingly prevent stroke in patients with NRAF with or without a history of stroke or TIA. The target degree of anticoagulation is an INR between 2.0 and 3.0. Any degree of anticoagulation with less than an INR of 2.0 will not provide full protection, any greater anticoagulation is no more effective, and an INR greater than 4.0 increases the risk of hemorrhage. Patients 65 years or younger without any risk factor do no better with warfarin than with aspirin or placebo, and should not be anticoagulated. All older patients or those with risk factors but without contraindications gain significant stroke prevention with warfarin anticoagulation as recommended above.