Obtaining only one electrocardiogram would have missed 15% of patients with STEMI in a single prehospital system.
Prehospital detection of acute ST-segment-elevation myocardial infarction (STEMI) facilitates transport of patients directly to percutaneous coronary intervention (PCI)-capable centers, and earlier detection lowers mortality. To assess whether performance of serial electrocardiograms (ECGs) improves detection of STEMI, researchers reviewed records for 325 consecutive patients with STEMI who were transported by the Toronto emergency medical services (EMS) system during 1 year.
If STEMI was not detected on the first ECG in a patient with symptoms suggestive of myocardial ischemia, the EMS protocol required performing a second ECG after the patient was loaded into the ambulance and, if necessary, a third ECG in the ambulance bay at the receiving hospital. When the automated interpretation recorded STEMI on any ECG and the paramedic agreed, the patient was transported directly to the PCI suite, bypassing the hospital's emergency department (false-positive activation rate, 15.6%).
STEMI was detected on first ECGs in 275 patients (84.6%), on second ECGs in an additional 30 patients (cumulative percentage, 93.8%), and on third ECGs in an additional 20 cases (cumulative percentage, 100%). STEMI evolved rapidly; the median times between first and second ECGs and between second and third ECGs were 11 and 9 minutes, respectively. Of STEMIs identified on second and third ECGs, 90% were identified within 25 minutes after the first ECG.
Verbeek PR et al. Serial prehospital 12-lead electrocardiograms increase identification of ST-segment elevation myocardial infarction. Prehosp Emerg Care 2011 Sep 28; [e-pub ahead of print].