2. Time from medication administration to heart rate and rhythm control. Additionally, currently guidelines consider BB or DT medications to slow AF/FL; however, there are some suggestions that BB may not only slow heart rate in AF/FL (as does DT) but also increase all AF/FL conversion from AF/FL to normal sinus rhythm(2), and aid in maintaining normal sinus rhythm (NSR) after cardioversion (10). With recent onset AF/FL occurring within 48 hours prior to the arrival to the ED, approximately 50% of AF/FL patients convert to normal rhythm spontaneously within 24 hours after arrival to the ED (6), making evaluation of current limited studies difficult. Thus, the investigators wish to examine the effect of initial medication strategy on time to NSR in a larger sample than has been previously performed.