Decreasing time to first shock: Routine application of defibrillation pads in prehospital STEMI

Four percent of ST-elevation myocardial infarctions (STEMIs) are complicated by an out-of-hospital cardiac arrest (OHCA). Research has shown that shorter time to initial defibrillation in patients with ventricular fibrillation/tachycardia (VF/VT) arrests increases favourable neurologic survival. The purpose of this study is to determine whether routine application of defibrillation pads in patients with prehospital STEMI decreases the time to initial defibrillation in those who suffer OHCA.

This was a health records review for adult patients diagnosed with STEMI in the prehospital setting from January 2012 to July 2016. Patients were included if they had a 12 lead ECG indicative of STEMI and subsequently suffered VF/VT OHCA while in paramedic care. This study was designed to evaluate the effects of the "pads-on" protocol in a pre (Jan 2012-May 2014) /post implementation fashion (Jun 2014- Jul 2016). Records were reviewed for relevant patient and event features. T-test was used to measure the difference between mean times to defibrillation.

446 patients were diagnosed with prehospital STEMI. 11 suffered OHCA while in paramedic care. The mean (SD) age was 66.0 (9.3) and 55% were female. In the 4 patients treated with the "pads-on" protocol, the mean time to initial defibrillation was 17.7 seconds, compared to 72.7 seconds in patients who had pads applied following arrest (Δ 55.0 sec [95% CI 22.7-87.2 s]).

Routine application of defibrillation pads in STEMI patients who suffer OHCA decreases time to initial defibrillation, which has previously been demonstrated to increase favourable neurologic survival.