Rapid identification of out-of-hospital cardiac arrest (OHCA) and delivery of bystander chest compressions in patients with ventricular fibrillation are key elements in the chain of survival. The timeliness of dispatcher-assisted CPR may improve survival in such patients. The Medical Priority Dispatch System (MPDS©) has recently introduced a streamlined process for emergency medical dispatchers (EMDs) that provides early identification of OHCA and rapid delivery of chest compression instructions in version 13.0, known as the Obviously Not Breathing Fast Track (Fast Track) feature. The primary objective was to determine elapsed time to dispatcher-instructed CPR, as well as elapsed time to bystander initiation of chest compressions for cases where EMDs did and did not use the MPDS v13.0 Fast Track feature. A secondary objective was to identify barriers encountered by bystanders in completing the delivery of prompt chest compressions.