Impact of Atrial Fibrillation Case Volume in the Emergency Department on Early and Late Outcomes of Patients With New Atrial Fibrillation.

Study objective To define the association between atrial fibrillation case volume in the emergency department and death or all-cause hospitalization at 30 days and 1 year in patients with new atrial fibrillation. Secondary objectives examined repeat ED visits and the management of atrial fibrillation within 90 days. Methods We identified all adults presenting to an ED in Alberta, Canada, with a new primary diagnosis of atrial fibrillation/flutter between 2009 and 2015 using International Classification of Diseases, 10th Revision code I48. Volume was classified in tertiles weighted by annual ED number of atrial fibrillation cases. The association between volume and outcomes was evaluated using generalized linear mixed models, adjusting for prognostically important covariates as fixed effects and ED as a random effect to account for potential clustering within EDs. Results The tertiles consisted of 4 high, 9 medium, and 68 low atrial fibrillation volume EDs, with 4,217, 4,193, and 4,112 patients, respectively. Volume was not independently associated with the primary outcome or individual components. However, medium- and high-volume EDs had fewer repeat ED visits at 30 days (respective adjusted odds ratio [aOR] 0.75 [95% confidence interval {CI} 0.66 to 0.87] and 0.64 [0.52 to 0.79]) and 1 year (respective aOR 0.77 [95% CI 0.67 to 0.90] and 0.71 [0.56 to 0.90]). Fewer patients were admitted from medium- (37.1%) and high- (32.0%) compared with low-volume (39.5%) EDs. Patients attending medium- and high-volume EDs were more likely to be cardioverted (aOR 3.28 [95% CI 1.94 to 5.53] and 3.81 [1.39 to 10.48] for medium- and high-volume EDs, respectively). Conclusion Treatment in higher volume EDs was associated with significantly lower admission rates and repeat ED visits but no difference in survival.