Patients With Atrial Fibrillation and an Alternative Primary Diagnosis in the Emergency Department: A Description of their Characteristics and Outcomes

Authors

  • Clare L. Atzema MD, MSc,

    Corresponding author
    1. Division of Emergency Medicine, Department of Medicine, University of Toronto, Toronto, ON, Canada
    2. Sunnybrook Health Sciences Centre, Toronto, ON, Canada
    • Institute for Clinical Evaluative Sciences, Toronto, ON, Canada
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  • Kevin Lam,

    1. Institute for Clinical Evaluative Sciences, Toronto, ON, Canada
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  • Christine Young,

    1. Institute for Clinical Evaluative Sciences, Toronto, ON, Canada
    2. Sunnybrook Health Sciences Centre, Toronto, ON, Canada
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  • Nicole Kester-Greene MD

    1. Division of Emergency Medicine, Department of Medicine, University of Toronto, Toronto, ON, Canada
    2. Sunnybrook Health Sciences Centre, Toronto, ON, Canada
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  • The Heart and Stroke Foundation of Ontario had no involvement in the design or conduct of the study, data management or analysis, or manuscript preparation, review, or authorization for submission. This study was supported by the Institute for Clinical Evaluative Sciences (ICES), which is funded by an annual grant from the Ontario Ministry of Health and Long-Term Care (MOHLTC). It was also supported by the Department of Emergency Services, Sunnybrook Health Sciences Centre, the Canadian Cardiovascular Outcomes Research Team, and the Institute for Clinical Evaluative Sciences. The opinions, results, and conclusions reported in this paper are those of the authors and are independent from the funding sources. No endorsement by ICES or the Ontario MOHLTC is intended or should be inferred.

Address for correspondence: Clare Atzema MD, MSc; e-mail: clare.atzema@ices.on.ca. Reprints will not be available.

Abstract

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.

Resumen

Pacientes con Fibrilación Auricular y un Diagnóstico Principal Alternativo en el Servicio de Urgencias: Una Descripción de Sus Características y Su Evolución

Objetivos

La fibrilación auricular es frecuente en el servicio de urgencias (SU). Los porcentajes de mortalidad a los 30, 90 y 365 días para los pacientes del SU con un diagnóstico principal de fibrilación auricular son del 4%, 6% y 11%, respectivamente. No existen datos de las características y los resultados de los pacientes del SU con fibrilación auricular que tienen un diagnóstico principal alternativo en el SU.

Metodología

En este estudio de cohorte retrospectivo de un único centro, se identificaron todos los electrocardiogramas realizados con fibrilación auricular confirmada en el SU desde abril del 2007 a marzo 2008. Se excluyeron las visitas repetidas al SU. Se excluyeron los electrocardiogramas asociados con un diagnóstico principal de fibrilación auricular en el SU, y del resto de electrocardiogramas de los pacientes con un diagnóstico principal diferente en el SU, se seleccionó la mitad de forma aleatorizada. El resultado principal fue la mortalidad por cualquier causa a los 30, 90 y 365 días tras la visita al SU, obtenida a través de un enlace a la base de datos de mortalidad de toda la provincia. Se realizó un análisis secundario mediante una regresión logística para comparar la mortalidad a 90 días de estos pacientes con aquéllos con diagnóstico principal de fibrilación auricular en el SU durante el mismo periodo del estudio.

Resultados

De las 768 visitas al SU clasificadas, se escogieron 416 historias clínicas. La media de edad fue de 80,3 años (DE 11,8 años) y el 50,7% fueron mujeres. Dos tercios tenían una historia previa de fibrilación/fluter auricular, 300 (72,1%) tuvieron una puntuación de CHADS2 ≥ 2, uno falleció en el SU y 275 (66,1%) ingresaron. El diagnóstico principal más frecuente en el SU fue la insuficiencia cardiaca congestiva (12%), la neumonía (6%) y el dolor torácico indeterminado (6%); mientras que los diagnósticos más comunes en los ingresados fueron la insuficiencia cardiaca congestiva (15%), la exacerbación de la enfermedad pulmonar obstructiva crónica (6%), la fibrilación auricular (5%) y la neumonía (5%). La mortalidad a los 30, 90 y 365 días fue del 10,6% (IC 95% = 7,8% a 14,0%), 17,4% (IC 95% = 13,9% a 21,5%), y 34,2% (IC 95% = 29,6% a 39,0%), respectivamente. Tras el análisis ajustado, un diagnóstico principal alternativo en el SU se asoció con un incremento del riesgo de muerte (OR 2,75; p = 0,01).

Conclusiones

Los pacientes atendidos en el SU con fibrilación auricular y un diagnóstico principal diferente son de mayor es edad y tienen mayor porcentajes de mortalidad a corto y largo plazo: la mortalidad fue tres veces mayor que en los pacientes con un diagnóstico principal de fibrilación auricular en el SU. Futuros estudios de la fibrilación auricular en el SU deberían distinguir entre estas dos poblaciones y la potencial contribución de la fibrilación auricular a la mortalidad en este escenario con otros diagnósticos principales.

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