The authors suggest a new method of choice of the drug (quinidine or cordarone) for the maintenance antiarrhythmic therapy after sinus rhythm recovery in patients with permanent atrial fibrillation, in patients with rheumatic heart disease and coronary heart disease. The method is based on the formalized prediction of the results of cardioversion and on the distinguishing groups with a good and bad prognosis. In the former group, both drugs can be administered, in the latter group, it is desirable that cordarone may be used.