Probability of a shockable presenting rhythm as a function of EMS response time.

Introduction: Survival from cardiac arrest is associated with having a shockable presenting rhythm (VF/pulseless VT) upon EMS arrival. A concern is that several studies have reported a decline in the incidence of VF/PVT over the past few decades. One plausible explanation is that contemporary cardiovascular therapies, such as increased use of statin and beta blocker drugs, may shorten the duration of VF/PVT after arrest.