Atrial fibrillation (an abnormal rhythm in the upper chamber of the heart) is a common supraventricular arrhythmia (a type of abnormal heart rhythm) for which antiarrhythmic therapy is often prescribed. The primary goals of therapy are to maintain sinus rhythm (normal heart rhythm) and to reduce the occurrence of episodes of atrial fibrillation. Azimilide may have an effect on increasing the time to first recurrence of symptomatic atrial fibrillation or atrial flutter and symptomatic paroxysmal supraventricular tachycardia (other types of abnormal heart rhythms).