Atrial Fibrillation: Restoration and Maintenance of Sinus Rhythm and Indications for Anticoagulation Therapy

PURPOSE: To review the efficacy and safety of electrical and pharmacologic conversion of atrial fibrillation, strategies for maintenance of sinus rhythm, and the importance of antithrombotic therapy. DATA SOURCES: English-language trials were identified from the MEDLINE database through 1995, bibliographic references, Current Contents, textbooks, and recent abstracts. STUDY SELECTION: Randomized trials (including abstracts) were selected. Cohort studies were used if randomized trials were not available. DATA EXTRACTION: Study design and data were extracted from clinical trials. Statistical analysis of combined data was not appropriate, given the marked variations in study designs and study populations. DATA SYNTHESIS: Cardioversion restores sinus rhythm in more than 80% of patients. In atrial fibrillation of recent onset, pharmacologic regiments have a success rate of 40% to 90%. Sinus rhythm at 1 year is maintained in 30% of patients without antiarrhythmic therapy but in 50% of patients with such therapy. The efficacy and safety of antiarrhythmic drugs relative to one another are not established because trials done to date have been small and cases vary. Successful cardioversion and maintenance of sinus rhythm are most predictable when the duration of atrial fibrillation is brief. Warfarin reduces the incidence of ischemic strokes and emboli in patients with nonvalvular atrial fibrillation from 4.5% to 1.4% per year. Aspirin (325 mg/d) appears to be equally effective in patients younger than 75 years of age who do not have hypertension or a history of thromboembolism or recent heart failure. Although warfarin is more effective than aspirin in preventing embolic strokes in patients older than 75 years of age, it may increase the incidence of hemorrhagic stroke and result in a similar rate of disabling stroke. CONCLUSION: Cardioversion remains the preferred method with which to re-establish sinus rhythm. Long-term antiarrhythmic therapy is warranted only if recurrences or initial clinical instability are seen; pro-arrhythmic concerns and potential side effects should guide drug selection. Antithrombotic therapy is indicated for all patients older than 60 years of age and in all patients younger than 60 years of age who have clinical evidence of a primary cardiac disorder.