Individuals experiencing chest pain who had ECG assessments prior to arriving at the hospital experience a significantly reduced time-to-treatment or door-to-balloon (D2B) time, based on a study in the January issue of Catheterization and Cardiovascular Interventions (CCI).
When EMS personnel responding to cardiac emergencies obtained ECGs of the subjects in the field, the mean D2B time was 60.2 minutes compared with 90.5 minutes for in-hospital ECGs, according to the authors. This advanced assessment significantly reduced D2B by allowing patients to bypass the ER and be transported directly to the cardiac cath lab for reperfusion treatment.
The researchers, led by Shukri David, MD, from Providence Hospital and Medical Center in Southfield, Mich., conducted a prospective, observational study of D2B time in three hospitals in Southeast Michigan from Oct. 1, 2003 through April 30, 2008.
At each center, a protocol was initiated where EMS personnel obtained a 12-lead ECG during initial assessment in the field from patients with symptoms suggestive of STEMI. With pre-hospital ECGs, data is transmitted via cellular link to an ER computer receiving station where ER physicians interpret the information and upon diagnosis of STEMI, activate the cath lab team prior to the patient's arrival.
The authors said that similar data were collected for all patients who came to the ER without pre-hospital ECGs (the control group).
David and colleagues found that 241 patients with STEMI received in-hospital ECGs and 108 patients received pre-hospital ECGs. The mean age of patients in both groups was 59 years and roughly 72 percent were male. Baseline characteristics including cardiac risk factors were similar between the groups.
Notably, the researchers revealed a significantly lower proportion of pre-hosptial ECGs were obtained in African-American patients (15.7 percent) versus Caucasian (75.9 percent).
“The predominant cause of this disparity was that pre-hospital ECG capability only became available to the ambulances in the city of Detroit at the conclusion of this study," said David. According to the 2000 census approximately 82 percent of Detroit's population is African-American.
Researchers found that in-hospital mortality was 2 percent for the control group compared with no deaths in those patients with pre-hospital ECG. Patients in the in-hospital ECG group who presented during working hours waited 75 minutes prior to reperfusion treatment, while those presenting during off-hours (weekends and holidays) experienced a 98-minute wait time.
In the pre-hospital ECG group, there was a significant reduction in D2B time independent of presentation time, with 98 percent of patients in this group who were admitted during off-hours having treatment within 90 minutes.
“Our results re-emphasize the importance of early activation of the cardiac cath lab in order to improve time-to-reperfusion in patients with STEMI,” concluded David.