What are the contraindications for synchronized electrical cardioversion?

Updated: Nov 28, 2018
  • Author: Sean C Beinart, MD, MSc, FACC, FHRS; Chief Editor: Jose M Dizon, MD  more...
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Cardioversion is contraindicated for any arrhythmia that is known to be incessant, as these rhythms recur immediately or soon after.

Contraindications also include known digitalis toxicity–associated tachycardia, sinus tachycardia caused by various clinical conditions, and multifocal atrial tachycardia.

In addition, because patients with atrial fibrillation (AF, afib) are at risk for developing blood clots in the left atrium, predisposing them to increased stroke risk, patients who are not anticoagulated should not undergo cardioversion without a transesophageal echocardiographic study that can assess the presence of a left atrial thrombus. Even patients with atrial fibrillation who are optimally anticoagulated with non-vitamin K antagonist oral anticoagulants (NOACs) have a low but not negligible risk for thrombus in the left atrial appendage. [9]

Synchronized cardioversion should also not be used to treat ventricular fibrillation, because the cardioverter may not sense a QRS wave and may therefore fail to deliver a shock. Synchronized cardioversion is also not appropriate for the treatment of pulseless ventricular tachycardia (VT, vtach) or polymorphic (irregular) VT, as these require high-energy, unsynchronized shocks (ie, defibrillation doses). In addition, cardioversion is not effective for the treatment of junctional tachycardia. [8]

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