Nehme Z, et al. - In out-of-hospital cardiac arrest (OHCA) populations, researchers assessed the effect of increasing patient delays between symptom onset and activation of emergency medical services (EMS) following acute myocardial infarction. Findings revealed reduced survival in association with increasing delays in activating EMS before the onset OHCA.

Methods

• From the Victorian Ambulance Cardiac Arrest Registry, researchers included adult patients with anginal warning symptoms and subsequent EMS witnessed OHCA of presumed cardiac aetiology from 1 January 2003 and 31 December 2011.
• They used multivariable logistic regression to ascertain the impact of patient delay time (i.e. symptom onset to EMS call time) on survival to hospital discharge.

Results

• Researchers screened a total of 1,056 EMS witnessed OHCA.
• Of these, 515 (48.8%) reported chest pain or anginal equivalent symptoms.
• They noticed a median patient delay time of 25 min (interquartile range [IQR] 9–89 min); across survivors and non-survivors, this did not differ.
• However, significantly higher rates of non-shockable arrest rhythms and circulatory compromise were also evident among patients in lowest quartile of patient delay (≤8 min).
• In a multivariable model of survival to hospital discharge, a total of 16 baseline and clinical characteristics were tested, of which, the final model retained only 6, including: age, dyspnoea, vomiting, shockable arrest rhythm, systolic blood pressure, and patient delay time.
• In this study, every 30 min increase in patient delay time had an independent association with a 2.3% (95% CI: 0.4%, 4.1%; p=0.02) reduction in the odds of survival to hospital discharge.
• Every 30 min increase in patient delay time, among patients with ST-segment deviation on the pre-arrest ECG, was associated with a 3.4% reduction in the odds of survival (OR 0.966, 95% CI: 0.937, 0.996; p=0.03).