eMedicine Specialties > Emergency Medicine > Cardiovascular

Atrial Fibrillation: Differential Diagnoses & Workup

Author: Pierre Borczuk, MD, Assistant Professor of Medicine, Harvard Medical School, Associate in Emergency Medicine, Massachusetts General Hospital
Contributor Information and Disclosures

Updated: Jul 15, 2009

Differential Diagnoses

Multifocal Atrial Tachycardia
Wolff-Parkinson-White Syndrome

Other Problems to Be Considered

Narrow complex tachyarrhythmias
Wide complex tachyarrhythmias

Workup

Laboratory Studies

  • CBC (looking for anemia, infection)
  • Electrolytes and BUN/creatinine levels (looking for electrolyte disturbances or renal failure)
  • Cardiac enzymes - CK and/or troponin level (to investigate myocardial infarction as a primary or secondary event)
  • May include a D-dimer if the patient has risk factors to merit a pulmonary embolism workup
  • Thyroid function studies (looking for thyrotoxicosis, a rare, but not-to-be-missed, precipitant) may be sent from the ED, but results are not usually available to assist in decision-making.
  • Digoxin level may be obtained when appropriate (to look for subtherapeutic levels and/or toxicity). It is generally considered safe to administer digoxin to a patient with atrial fibrillation on digoxin for rate control without waiting for a level to return from the laboratory when the patient presents with atrial fibrillation with rapid ventricular response (RVR).
  • Toxicology testing

Imaging Studies

  • Chest radiographic findings are usually normal. Look for radiographic evidence of CHF as well as signs of lung or vascular pathology (pulmonary embolism, pneumonia).
  • If patients have a positive D-dimer result, they may require chest CT angiography to rule out pulmonary embolus.
  • Echocardiography may be used to evaluate for valvular heart disease, left and right atrial size, left ventricular (LV) size and function, left ventricular hypertrophy (LVH), and pericardial disease.
  • Transthoracic echocardiography has low sensitivity in detecting LA thrombus, and transesophageal echocardiography (TEE) is the required modality in this case.7

Other Tests

  • ECG: Absent P waves, replaced by irregular, chaotic fibrillatory waves, in the setting of irregular QRS complexes (see Media file 1). Look for aberrantly conducted beats after long-short R-R cycles (ie, Ashman phenomenon). Other features to look for on the ECG include LVH, preexcitation, bundle-branch blocks, acute or prior MI, and intervals (R-R, QRS, QT).

    ECG of controlled-rate atrial fibrillation.

    ECG of controlled-rate atrial fibrillation.

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    ECG of controlled-rate atrial fibrillation.

    ECG of controlled-rate atrial fibrillation.

  • Holter monitoring or event monitoring may be considered for those discharged from the ED (eg, in cases of paroxysmal AF not evident upon presentation).
  • Exercise testing might also be used in the outpatient setting to determine adequacy of rate-control, to reproduce exercise-induced EF, and to exclude ischemic pathology.

Procedures

  • Emergent electric cardioversion is indicated for an unstable patient with atrial fibrillation. This is not commonly required. Instability is generally considered to be present when any of the following are present and when no cause other than the atrial fibrillation is contributing:  
    • Symptomatic hypotension
    • Altered mental status or loss of consciousness
    • Acute coronary syndrome with active myocardial ischemia evident either by symptoms (angina) or ECG, or acute myocardial infarction
    • Hypoxia

More on Atrial Fibrillation

Overview: Atrial Fibrillation
Differential Diagnoses & Workup: Atrial Fibrillation
Treatment & Medication: Atrial Fibrillation
Follow-up: Atrial Fibrillation
Multimedia: Atrial Fibrillation
References
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References

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Further Reading

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Keywords

atrial fibrillation, AF, atrial fib, atrial fibrillation treatment, bradyarrhythmia, tachyarrhythmia, arrhythmia, heart disease, acute myocardial infarction, AMI, congestive heart disease, CHD, coronary artery disease, CAD, cardiovascular disease, heart attack, rhythm disturbance, atrioventricular node, AV node, palpitations, dyspnea, chest pain, angina, syncope, hypotension, congestive heart failure, CHF, jugular venous distension, hypertension, valvular heart disease, rheumatic heart disease 

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Contributor Information and Disclosures

Author

Pierre Borczuk, MD, Assistant Professor of Medicine, Harvard Medical School, Associate in Emergency Medicine, Massachusetts General Hospital
Pierre Borczuk, MD is a member of the following medical societies: American College of Emergency Physicians
Disclosure: Nothing to disclose.

Medical Editor

William Lober, MD, Associate Professor, Department of Medical Education, Division of Biomedical and Health Informatics, University of Washington School of Medicine
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Gary Setnik, MD, Chair, Department of Emergency Medicine, Mount Auburn Hospital; Assistant Professor, Division of Emergency Medicine, Harvard Medical School
Gary Setnik, MD is a member of the following medical societies: American College of Emergency Physicians, National Association of EMS Physicians, and Society for Academic Emergency Medicine
Disclosure: SironaHealth Salary Management position; South Middlesex EMS Consortium Salary Management position

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

David FM Brown, MD, Assistant Professor, Division of Emergency Medicine, Harvard Medical School; Vice Chair, Department of Emergency Medicine, Massachusetts General Hospital
David FM Brown, MD is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

 
 
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