NEW ORLEANS -- For patients with suspected ST-segment elevation MI (STEMI), having an electrocardiogram done in the ambulance shortens the time spent in the emergency department before going to the cardiac catheterization lab, researchers found.
It took a median of 16 minutes from hospital arrival to activation of the cath lab team for patients who arrived by ambulance and 32 minutes for those who arrived by other means (P=0.006), according to James McCabe, MD, of the University of California San Francisco.
The difference was almost entirely attributed to an EKG in the ambulance, McCabe reported at the American College of Cardiology meeting here.
Action Points
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
- Explain that for patients with suspected STEMI having an EKG done in the ambulance shortens the time spent in the ER before going to the cardiac catheterization lab.
- Note that the benefit of arrival by ambulance remained after controlling for numerous variables, including demographics, risk factors, illness severity, and EKG characteristics.
Those who received a pre-hospital EKG had a door-to-lab time of 10 minutes, about one-third the time for those who did not have an in-transit EKG (28 minutes). That translated into a 26% shorter door-to-balloon time (P=0.004), a metric used in quality-improvement assessments.
The benefit of arrival by ambulance remained after controlling for numerous variables, including demographics, risk factors, illness severity, and EKG characteristics.
"If you or a loved one are having symptoms consistent with a heart attack, do take an ambulance. You're doing yourself a disservice if you don't," McCabe said at a press briefing.
"And when you get in the ambulance, do what you can to get an electrocardiogram because the benefits of ambulance use don't stop when the ambulance stops at the door to the hospital," he continued. "There [is a] ripple effect and increased benefit through the initial stages of the hospitalization."
Based on evidence suggesting that ambulance use was associated with shorter door-to-balloon time, McCabe and his colleagues designed the Activate-SF Registry to look at the effect of transport method for patients with suspected STEMI who were referred to the cath lab, regardless of outcome or ultimate diagnosis.
The analysis included 356 patients taken to a tertiary care hospital and an urban trauma center in San Francisco; 56% of the patients took an ambulance to the hospital. Of those who arrived by ambulance, 57% had an EKG done before reaching the hospital.
McCabe said that ambulance personnel in the city are not routinely trained to interpret EKGs, and do not have the capability to electronically transmit them to hospitals before arrival, although they soon will.
So the benefits of pre-hospital EKG in cutting the time spent in the emergency department came from walking into the hospital with an EKG in hand, he said.
After adjustment for numerous potential confounders, having a pre-hospital EKG was associated with faster times from EKG to activation of the cath lab team (by 66%), from door to activation (by 62%), from door to cath lab (by 44%), and from door to balloon (by 26%) -- P<0.05 for all.
Those results are despite the fact that patients who arrived by ambulance, although generally similar to the rest of the patients in terms of demographics, risk factors, and EKG characteristics, were sicker and required more stabilization before being moved to the cath lab.
Patients who went by ambulance to the hospital were more likely to have cardiac arrest, a need for intubation, a systolic blood pressure below 100 mm Hg, a requirement for a pressor, and a heart rate less than 50 beats-per-minute (P<0.05 for all).
McCabe said future research may focus on other factors associated with time spent in the emergency department, such as overcrowding and time of day, and on ways to increase the use of pre-hospital EKG.
Many patients in the study did not get an EKG despite taking an ambulance to the hospital, primarily because of language barriers.
"Working on translatability of symptoms in the ambulance and perhaps just broadening use of pre-hospital EKG would go a long way," McCabe said.
Disclosures
McCabe reported that he has no conflicts of interest.
Primary Source
American College of Cardiology
Source Reference: McCabe J, et al "Ambulance use or its lack -- impact on triage of patients with ST-elevation myocardial infarctions by emergency physicians" ACC 2011; Abstract 1099-150.