A recent study was conducted in the city of Calgary, Canada to determine the impact of rapidly delivering acute myocardial infarction (MI) patients to the single interventional facility in the city. Can the use of pre-hospital 12-lead ECG while in transit effectively identify candidate patients for acute coronary intervention?
Review of: De Villiers JS, Anderson T, McMeekin JD: Expedited transfer for primary percutaneous coronary intervention: a program evaluation. CMAJ. Canadian Medical Association Journal. 176(13):1833 1838, 2007.
The Science: This study was conducted in the city of Calgary, Canada. The goal of the researchers was to determine the impact of rapidly delivering acute myocardial infarction (MI) patients to the single interventional facility in the city. The study was conducted in three phases. During Phase One EMS obtained and interpreted a 12-lead ECG and transported the patient to the nearest hospital where a physician examined the ECG in the ambulance bay and if acute MI was confirmed the patient was sent on to the interventional facility without ever being taken out of the ambulance. This occurred from 7 a.m. to 5 p.m. daily during Phase One and was expanded to 24 hours a day during Phase Two. In Phase Three the 12-lead ECG was transmitted from the patient s bedside to the interventional facility and if acute MI was confirmed, the patient was transported directly to the cath lab bypassing the nearest hospital.
A total of 358 patients were enrolled and the mean time from door-to-balloon was 62 minutes. They achieved door-to-balloon times of less than 60 minutes in 48.9% of cases and less than 90 minutes in 78.8%. The internationally accepted standard is 90 minutes.
They concluded that institution of an expedited transfer pathway resulted meeting the published door-to-balloon times in a significant majority of the cases and was a feasible use of pre-hospital 12-lead ECG to identify candidate patients for acute coronary intervention.
The Street: This is another very compelling article to add to the growing list of studies demonstrating the value of EMS in identifying and rapidly transporting acute coronary syndrome patients to definitive care. However, this study appears to only answer one question while raising several others that I hope the authors will answer.
They admit that the most significant time reduction occurred when they moved to Phase Three where they bypassed the nearest hospital but they failed to provide the data for this conclusion in the paper. It would be interesting to know why they even considered using the first two phases. In the U.S. it would be impossible to perform a rapid evaluation in the ambulance bay and transfer without admitting the patient to the ER and completing Emergency Medical Treatment and Active Labor Act (EMTALA) forms.
Another question is why did they change from paramedic interpretation to transmission of ECG between the first two phases and the third phase? Did they find that paramedic interpretation was not dependable enough to warrant bypassing the closest hospital for the interventional facility?
I challenge the authors to answer these questions because EMS systems in the U.S. continue to struggle with the proper way to structure an expedited transfer program.