Atrial Fibrillation Differential Diagnoses

Updated: Nov 18, 2019
  • Author: Lawrence Rosenthal, MD, PhD, FACC, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
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Diagnostic Considerations

The diagnosis of atrial fibrillation (AF) is based on the physical finding of an irregular heart rhythm and is confirmed with an electrocardiogram (ECG) or rhythm strip.

When AF is suspected during auscultation of the heart with irregularly irregular beats, obtaining a 12-lead ECG is the next step. Because AF is due to irregular atrial activation at the rate of 350-600 bpm with irregular conduction through the atrioventricular node, it appears on ECG as irregularly irregular narrow complex tachycardia. The F waves may be seen as fibrillatory waves or may be absent. Unless the heart is under excess sympathetic or parasympathetic stimulation, the ventricular rate is usually between 80 and 180 bpm.

With an abnormality in the intraventricular conduction system, the QRS complexes may become wide. It is important to pay attention to the ECG signs of associated cardiac diseases, such as left ventricular hypertrophy and preexcitation.

Differential Diagnoses