Podcast 1018: Occult Ventricular Fibrillation on Echocardiography

Contributor: Aaron Lessen, MD

Educational Pearls:

Big question in cardiac arrest: is the rhythm shockable?

Shockable: ventricular fibrillation (VF) and pulseless ventricular tachycardia

Non-shockable: asystole and pulseless electrical activity (PEA)

Rhythm classification is typically based on ECG, but echocardiography can directly visualize myocardial fibrillation

Occult VF: a rhythm that appears non-shockable on ECG but demonstrates VF on echocardiography

A 2025 multicenter prospective study looked at 811 patients with out-of-hospital cardiac arrest

5.3% had occult VF detected by echocardiography

Of the patients with occult VF:

81.4% had PEA on ECG

18.6% had asystole on ECG