Comparison of Diltiazem and Metoprolol in the Management of Acute Atrial Fibrillation or Atrial Flutter

Acute atrial fibrillation is the most common sustained, clinically significant dysrhythmia encountered in the emergency department (ED) and the most common dysrhythmia treated by emergency physicians. Atrial flutter is less common than atrial fibrillation but its management in the ED is very similar, and the majority of patients with atrial flutter also have atrial fibrillation. Symptomatic relief and ventricular rate control are generally the primary therapeutic objectives in the ED management of acute atrial fibrillation and flutter (AFF). The need for swift, appropriate action by the emergency physician is highlighted by the fact that up to 18% of patients with AFF develop potentially life-threatening complications such as congestive heart failure, hypotension, ventricular ectopy, respiratory failure, angina and myocardial infarction. Both beta-blocking agents and calcium channel blockers are commonly used to treat AFF in the ED. Metoprolol is the most commonly used beta-blocker; and diltiazem is the most frequently used calcium channel antagonist.[8] Diltiazem was released by the FDA for treatment of AFF in 1992. Shreck et al. were the first to demonstrate both the efficacy of diltiazem in the ED management of AFF with rapid rate and its clear superiority over the previously most commonly used pharmacologic agent, digoxin. To date, only one prospective, randomized trial has compared the effectiveness of a calcium channel blocker (diltiazem) with a beta-blocker (metoprolol) for rate control of AFF in the ED. Despite the relatively small sample size (n=20 in each group) the authors concluded that both pharmacologic agents were similarly effective. In order to test this finding, the investigators conducted a prospective comparison of metoprolol and diltiazem for the management of patients presenting to the ED with AFF with rapid ventricular rate.