Strokes are responsible for significant morbidity and mortality. Persons who have chronic atrial fibrillation are at higher risk of having a stroke. Previously, anticoagulation with warfarin was instituted only in persons with atrial fibrillation associated with valvular problems. More recently, five studies have shown a clear benefit to using warfarin in persons with atrial fibrillation related to nonvalvular conditions, such as hypertension, coronary artery disease, and heart failure. Patients who were given warfarin in therapeutic dosages, as measured by prothrombin time ratios and international Normalized Ratios (INRs), had a significant reduction in stroke risk ranging from 37 to 79% in the five studies.
The outcomes of these five studies have changed the way persons with chronic, nonvalvular atrial fibrillation are managed. Health care providers play a key role in the counseling of patients who are considering the use of warfarin, the patient education regarding potential complications and drug interactions, and the ongoing monitoring and laboratory testing needed for dosage adjustments.