Which electrocardiography findings confirm the diagnosis of atrial fibrillation (Afib) (AF)?

Updated: Apr 09, 2019
  • Author: Lawrence Rosenthal, MD, PhD, FACC, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
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Answer

Electrocardiographic (ECG) findings usually confirm the diagnosis of atrial fibrillation (AF) and include the following:

  • The ventricular rate is typically irregular (irregular QRS complexes)

  • Discrete P waves are absent, replaced by irregular, chaotic F waves, as shown in the image below

  • Ventricular rate varies from 130-168 beats per min Ventricular rate varies from 130-168 beats per minute. Rhythm is irregularly irregular. P waves are not discernible.
  • Look also for aberrantly conducted beats after long-short R-R cycles (ie, Ashman phenomenon)

  • Heart rate (typically in the 110-140 range, but rarely over 160-170)

  • Preexcitation

  • Left ventricular hypertrophy

  • Bundle-branch block or intraventricular conduction delay

  • Acute or prior myocardial infarction

QRS duration appears to be an independent predictor of incident AF among women, but not in men, based on findings from 15,314 participants from the Atherosclerosis Risk in Communities (ARIC) study. [51] The underlying mechanism for the difference between men and women is not yet clear.


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