What ECG findings confirm atrial fibrillation (Afib) (AF)?

Updated: Nov 18, 2019
  • Author: Lawrence Rosenthal, MD, PhD, FACC, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
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Findings from 12-lead electrocardiography (ECG) usually confirm the diagnosis of AF and include the following:

  • Typically irregular ventricular rate (QRS complexes)

  • Absence of discrete P waves, replaced by irregular, chaotic F waves

  • Aberrantly conducted beats after long-short R-R cycles (ie, Ashman phenomenon)

  • Heart rate (typically 110-140 beats/min, rarely >160-170 beats/min)

  • Preexcitation

  • Left ventricular hypertrophy

  • Bundle-branch block or intraventricular conduction delay

  • Acute or prior myocardial infarction (MI)

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