Patients with atrial fibrillation and an alternative primary diagnosis in the emergency department: a description of their characteristics and outcomes.

OBJECTIVES: Atrial fibrillation is common in the emergency department (ED). Mortality rates at 30, 90, and 365 days for ED patients with a main diagnosis of atrial fibrillation are 4, 6, and 11%, respectively; there are no data on the characteristics and outcomes of ED patients with atrial fibrillation who have alternative primary ED diagnoses.
METHODS: In this single-site, retrospective cohort study, all electrocardiograms (ECGs) with confirmed atrial fibrillation performed in the ED from April 2007 to March 2008 were identified. Repeat ED visits were excluded. ECGs associated with a primary ED diagnosis of atrial fibrillation were excluded, and from the remaining ECGs of patients with a different primary ED diagnosis, half were randomly selected for abstraction. The main outcome measure was all-cause mortality at 30, 90, and 365 days post-ED visit, derived from linkage to a provincewide mortality database. As a secondary analysis, logistic regression was used to compare 90-day mortality of these patients to those with primary ED diagnoses of atrial fibrillation seen during the same time period.
RESULTS: Of 768 qualifying index ED visits, 416 charts were abstracted. Mean (± standard deviation [SD]) age was 80.3 (± 11.8) years, and 50.7% were female. Two-thirds had a previous history of atrial fibrillation/flutter, 300 (72.1%) had a CHADS2 score ≥ 2, one died in the ED, and 275 (66.1%) were admitted. The most common primary ED diagnoses were congestive heart failure (12%), pneumonia (6%), and chest pain not yet diagnosed (6%), while most common in-hospital diagnoses were congestive heart failure (15%), chronic obstructive pulmonary disease exacerbation (6%), atrial fibrillation (5%), and pneumonia (5%). Mortalities at 30, 90, and 365 days were 10.6% (95% confidence interval [CI] = 7.8% to 14.0%), 17.4% (95% CI = 13.9% to 21.5%), and 34.2% (95% CI = 29.6% to 39.0%), respectively. In the adjusted analysis, an alternative primary ED diagnosis was associated with an increased risk of death (odds ratio [OR] = 2.75; p = 0.01).
CONCLUSIONS: Patients seen in the ED with atrial fibrillation and different primary ED diagnoses are older and have high short- and long-term mortality rates: mortality was three times higher than in patients with primary ED diagnoses of atrial fibrillation. Future studies of atrial fibrillation in the ED should distinguish between these two populations and the potential contribution of atrial fibrillation to mortality in the setting of other primary ED diagnoses.