- If subjects are receiving antiarrhythmic drug therapy (Class I or Class III AAD)for an arrhythmia other than typical atrial flutter, then the subject needs to be controlled on their medication for at least 3 months. If the subject had typical atrial flutter before starting the AAD(s) (Class I or Class III) and then subsequently had another arrhythmia (i.e. atrial fibrillation), then the 3 month AAD criteria will not apply.