Ventricular fibrillation is a non-perfusing (cardiac arrest) rhythm. It is fatal if not treated with a defibrillatory “shock”

If V Fib. is not terminated, the amplitude of the deflections will decrease over time as the myocardial energy stores are depleted. The rhythm is said to degenerate from “coarse VF” to “fine VF”. A fine VF can be understood to have a relatively poorer prognosis.