Pre-Hospital STEMI Identification Improves Post-PCI Survival

A pre-hospital triage strategy in which patients suspected of having ST-segment elevation myocardial infarction (STEMI) undergo electrocardiography in the ambulance and are sent directly to a center equipped for percutaneous coronary intervention (PCI) improves door-to-balloon (D2B) times as well as survival, according to a study published in the December 2012 issue of JACC: Cardiovascular Interventions

Albert W. Chan, MD, of the Royal Columbian Hospital (British Columbia, Canada), and colleagues compared the procedural times and survival of STEMI patients who were diagnosed via a prehospital triage strategy (n = 167) and those who underwent interhospital transfer from a local hospital to a PCI center after diagnosis (n = 427).

The regional program under evaluation included ambulances equipped with a 12-lead electrocardiogram (ECG) and personnel trained in advanced life support and ECG interpretation. Once a confirmed diagnosis of STEMI was made, the ECG results were transmitted to the PCI center for activation of the cath lab.

Better Results, Faster Times

Patients who underwent pre-hospital triage had a significant improvement in the standard 90-minute D2B time (80.4% vs. 8.7%; P < 0.001). Prehospital diagnosis of STEMI also resulted in a significant improvement in in-hospital, 30-day, and 1-year mortality (table 1), and remained an independent predictor after multivariate adjustment for lower 30-day (OR 0.26; 95% CI 0.1-0.7; P = 0.007) and 1-year mortality (HR 0.37; 95% CI 0.18-0.75; P = 0.006).

Table 1. Comparison of Mortality Rates

In addition to D2B times, prehospital triage resulted in significant improvements in median symptom-to-balloon time and first medical contact-to-balloon time compared with those who underwent interhospital transfer (table 2).

Table 2. Comparison of Time Intervals to Revascularization

Comparisons of pre-procedural TIMI flow grade 3 showed no significant difference between the 2 patient groups; however, postprocedure, those patients who received prehospital triage were more likely to achieve TIMI flow grade 3 than those who underwent interhospital transfer (97.6% vs. 91.4%; P = 0.02).

Improved Survival Not Only Point

In a telephone interview with TCTMD, Dr. Chan said the paper is the first to show a mortality benefit of a prehospital triage strategy in such a large geographic area.

“The study group encompassed a large region with distances up to 75 minutes from the furthest hospital to a PCI center, down to the nearest hospital with a travel time of about 15 minutes,” Dr. Chan said.

Ajay J. Kirtane, MD, SM, of Columbia University Medical Center (New York, NY), told TCTMD in a telephone interview that the significant improvement in survival was surprising given the study’s small size.

“It is not entirely clear that if you were to replicate this study in a larger patient population that you would get the degree of mortality reduction that they observed,” Dr. Kirtane said.

However, he added that the survival improvement is not the most important piece of information. Instead, the improvements in terms of time to reperfusion are of great importance and could have significant policy implications, he said.

“This article is clear in demonstrating that if you do not have a PCI program and your hospital is bypassed, patients not only have shorter reperfusion times but potentially better outcomes,” Dr. Kirtane said.

Application in the United States

Currently, in Canada, the health care community is working to increase the number of ambulances with ECG transmission capability and the number of people trained in reading ECGs, according to Dr. Chan. Although numbers are increasing, they are still not at 100%.

Adoption of such programs in the United States may be more difficult though, Dr. Kirtane added.

“Right now in the United States, there are a lot of hospitals that want to take care of patients with acute MI,” he said. “Implementing a program like this could be political because smaller hospitals may not want to agree to being bypassed because it will decrease their emergency room volume.”

However, Dr. Kirtane noted that if physicians and hospitals were looking at this from a ‘big picture’ point of view, it is something they “absolutely should do, without question.”

Dr. Chan agreed, “If the goal of medical professionals and hospitals is to improve patient survival instead of competition, I think barriers should be minimized.

“Together with many other studies, it is clear that prehospital ECG leads to earlier diagnosis of STEMI and earlier activation of the cath lab, and that results in better outcomes for the patient,” he concluded.