Premature atrial contraction

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Premature atrial contractions (PACs) are common and typically benign premature beats characterized by an abnormal early P wave within a cardiac cycle. Less commonly, they can precipitate atrial fibrillation, atrial flutter, or SVT.[1]

Clinical Features

  • Palpitations
  • Shortness of breath
  • Anxiety
  • Asymptomatic

Differential Diagnosis



  • Obtain EKG and look for:
    • P waves that appear sooner than expected sinus beat
    • Ectopic P waves that have different morphology
    • Interval between normal P waves encompassing the PAC is less than twice the existing P-P cycle length (noncompensatory pause)[2]
EKG showing PACs
  • Rule out underlying conditions:
    • Chronic heart disease (increases prevalence of PACs)
    • Chronic lung disease (increases prevalence of PACs)
    • Drugs: cocaine, amphetamines, caffeine, nicotine, digoxin


  • No specific treatment necessary
  • If symptomatic, treat underlying disorder or discontinue offending agent.


  • Discharge home, no specific follow-up (unless identifiable underlying etiology that needs to be treated).

See Also

External Links


  1. Specific dysryhthmias. In: Marx K, Rosen P, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 8th ed. Philadelphia, PA: Elsevier/Saunders, 2014.
  2. Brady W, Laughrey T, Ghaemmaghami C. Cardiac rhythm disturbances. In Tintinalli's Emergency Medicine: A Comprehensive Guide. Tintinalli J, et al. ed. 8th ed. McGraw Hill. New York, NY, 2016.