Emergency Department Patients With Atrial Fibrillation or Flutter and an Acute Underlying Medical Illness May Not Benefit From Attempts to Control Rate or Rhythm

Study objective: Although the management and outcomes of emergency department (ED) patients with atrial fibrillation or flutter have been explored, such studies have typically excluded patients with acute underlying medical illnesses. We seek to describe the ED treatment and outcomes of these complex patients with atrial fibrillation or flutter. Methods: This retrospective descriptive cohort study used an ECG database from 2 urban EDs to identify consecutive ED patients with an ECG demonstrating atrial fibrillation or flutter from January 1, 2009, to December 31, 2009. We categorized patients with atrial fibrillation or flutter as complex according to prespecified criteria and then grouped them as being managed with rate or rhythm control attempts, or not. The primary outcome was safety of rate or rhythm control, measured by whether patients had a predefined adverse event or not. The secondary outcome was the success of rate or rhythm control, defined as rate control decreasing the pulse rate by 20 beats/min and successful rhythm control, both within 4 hours of treatment initiation. Descriptive statistics were used to compare the 2 groups. Results: Four hundred sixteen complex patients with atrial fibrillation or flutter were identified. Patients managed with rate or rhythm control were similar in all baseline characteristics and illness distribution to patients who were not managed in this manner. The 135 patients with attempted rate control (105) or rhythm control (30) had 55 adverse events (40.7%; 95% confidence interval [CI] 32.5% to 49.5%), whereas the 281 patients not managed with rate or rhythm control had 20 adverse events (7.1%; 95% Cl 4.5% to 10.9%), for a risk difference of 33.6% (95% Cl 24.3% to 42.5%) and a relative risk of 5.7 (95% Cl 3.6 to 9.1). Twenty of 105 patients (19.1%; 95% Cl 12.3% to 28.1%) were successfully rate controlled, whereas 4 of 30 (13.3%; 95% Cl 4.4% to 31.6%) were successfully rhythm controlled. Conclusion: In ED patients with complex atrial fibrillation or flutter, attempts at rate and rhythm control are associated with a nearly 6-fold higher adverse event rate than that for patients who are not managed with rate or rhythm control. Success rates of rate or rhythm control attempts appear low.