The most effective use of the ECG involves weighing its information along with the patient's medical history, cardiac risk factors, and physical examination. These criteria should be individually assessed and then compiled to help form an initial impression with a threshold to action. The isolated ECG tracing is not a perfectly sensitive or specific exam and therefore should not be used as a screening tool. ECG interpretation by EMS personnel has been shown to reduce the time required to initiate thrombolytic therapy once the patient arrives in the emergency department. This benefit is particularly true in the rural setting where a significant reduction in total mortality has been shown for patients treated with thrombolysis prior to arrival to the hospital.
Similar studies remain to be conducted in the urban environment.
Sufficient planning and monitoring of the program is critical to ensure that on scene times are not delayed. Other EMS systems have not been able to duplicate these results, with studies showing that times may be significantly prolonged. Kereiakes D, Gibler W, Martin L, et al. Guly, UM, Mitchell RG, Cook R, et al. Paramedics and Technicians are Equally Successful at Managing Cardiac Arrest Outside Hospital.