Diagnosing STEMI patients in the ambulance and notifying the cath lab en-route to a PCI center can triple the amount of patients who reach door-to-balloon (D2B) times that are 90 minutes or less compared with interhospital transport, according to a study in this month's Journal of the American College of Cardiology: Cardiovascular Interventions.
“Primary angioplasty is the preferred reperfusion therapy in STEMI if performed within 90 minutes of first medical contact by an experienced team of personnel in a high-volume center,” the authors wrote. “In real-world practice, only 10 percent of patients in the U.S. meet the current time goal in case of referral for primary angioplasty.”
Hendrik-Jan Dieker, MD, of the the Radboud University Medical Center in Nijmegen, the Netherlands, and colleagues assessed 581 patients who were referred for PCI at Radboud between January 2005 and December 2007 to evaluate how pre-hospital triage and direct transport to a PCI center can impact STEMI treatment.
If patients were diagnosed with STEMI (infarction of more than 15 mm) in the ambulance by means of a 12-lead pre-hospital ECG (Lifepak 12, Physio Control), the paramedic phoned a cardiology resident at the PCI center to prepare the cath lab before patient transport.
Study endpoints used were post-procedural TIMI flow grade and long-term mortality.
Of the 581 patients, all but one were diagnosed with STEMI. Also, 78 percent of patients were directly transferred to the PCI center, while 22 percent were referred to a non-PCI center.
Of the 454 patients directly transferred to the PCI center, 82 percent reached D2B times of 90 minutes or less compared to 23 percent of those transferred to non-PCI centers. Median symptom-to-balloon (time of symptom onset to balloon inflation) times were 149 minutes versus 219 minutes, respectively.
“Compared with interhospital transport, the rate of patients treated within the 90-minute time frame of the guidelines more than tripled,” the authors wrote.
Median D2B times for the two study arms were 24 minutes for those transported to PCI centers and 32 minutes for those transported to non-PCI centers. Additionally, the researchers found that symptom-to-9-1-1 call, 9-1-1 call-to-diagnosis and diagnosis-to-balloon times were all higher in the group of patients transported to non-PCI centers.
Patients transported directly to the PCI center exhibited lower one-year mortality rates (7 percent) and had higher rates of TIMI flow grade 3 (92 percent). These numbers for patients transported to non-PCI centers were 13 percent and 84 percent, respectively.
Median follow-up was 596 days and 64 patients died during follow-up.
“Pre-hospital diagnosis of STEMI with direct notification of the catheterization laboratory and subsequent transportation to the intervention center is an attractive treatment strategy,” the authors wrote.
“Direct transportation to the intervention center resulted in a reduction of about 50 minutes in the diagnosis-to-balloon time …. Our data underscore that efforts should be made to organize a large-scale implementation of an infrastructure of pre-hospital diagnosis and direct transport to the intervention center, with early notification of the catheterization laboratory from the ambulance,” Dieker and colleagues concluded.
In an accompanying editorial, Alice K. Jacobs, MD, and Claudia P. Hochberg, MD, of the Boston Medical Center, said that this study may present bias and confounding data due to the fact that there is a lack of randomization or propensity score matching.
“It is unclear why the symptom onset to 9-1-1 call and the 9-1-1 call to diagnosis were longer in the referral center group, whether the pre-hospital and referral center treatment protocols were similar, and whether the findings would be similar in lower risk (smaller infarct) patients,” Jacobs and Hochberg wrote.
However, they concluded: “Fortified by the momentum and success of D2B initiatives and as EMS changes direction to transport STEMI patients directly to PCI centers, we too must now change direction and reach beyond the primary emphasis on door-to-balloon time. Expanding our efforts to target patient and pre-hospital programs, in addition to interhospital and post-STEMI secondary prevention strategies, will improve the comprehensive care and outcomes for all STEMI patients wherever they may reside.”