Delays in treatment time, particularly a delay in first contact with emergency medical service (EMS) to balloon angioplasty, may increase mortality for STEMI patients, according to a study published in the Aug. 18 edition of the Journal of the American Medical Association.

“Timely reperfusion therapy with either fibrinolysis or primary PCI is recommended for patients with ST-segment elevation myocardial infarction,” the authors wrote. While door-to-balloon (D2B) delay has been used as a performance measure in triaging patients for primary PCI, the authors said that focusing on first contact to reperfusion therapy may be more appropriate.

Previous studies have shown that pre-hospital fibrinolysis resulted in earlier initiation or reperfusion and resulted in 15 to 21 lives saved per 1,000 treated patients.

To evaluate the link between system delays and outcomes in STEMI patients treated with PCI, Christian Juhl Terkelsen, MD, PhD, of the Aarhus University Hospital in Aarhus, Denmark, and colleagues measured the associations between treatment, patient, system and D2B delays and mortality in 6,290 STEMI patients.

The patients were identified using the Western Denmark Heart Registry between January 1, 2002, and December 31, 2008. Patients were enrolled in the study if they had STEMI or bundle-branch block MI, were transported by EMS and treated with primary PCI within 12 hours of the onset of symptoms.

The trial took place among three PCI centers in western Denmark and the mean follow-up period was 3.4 years. During the study, the cath lab was notified when there was a STEMI diagnosis, whether it was pre-hospital or in-hospital, and patients were directly admitted to the cath lab.

The researchers defined treatment delay as the time from symptom onset to guiding catheter insertion during primary PCI and system delay was defined as the time from contact with the EMS to guiding catheter insertion during PCI.

Of the 6,290 patients, 35 percent (n=2,183) were transported directly to a PCI center and bypassed a local hospital. The researchers found significant differences in system delays and D2B times when they compared patients who were field-triaged directly to a PCI center and those who were transferred from other hospitals.

Of the patients who were admitted directly to PCI centers,72 percent were treated with a system delay of 120 minutes or less. Thirty-five percent of those transferred from different hospitals saw system delays of 120 minutes or less and 48 percent of all EMS-transported patients saw a system delay of 120 minutes or less.

The researchers reported one-year cumulative mortality rates to be 9.3 percent.

After the researchers stratified data according to intervals of system delay, results showed that long-term mortality rates were 15.4 percent (n=43 patients) for patients who saw a system delay between 0 minutes and 60 minutes (n=347).

Of the 2,643 patients who saw delays of 61 minutes to 120 minutes, mortality rates were 23.3 percent (n=380). Additionally, 2,092 patients experienced delays of 121 minutes to 180 minutes and 1,127 patients experienced delays between 181 minutes and 360 minutes. Mortality rates for these delays were 28.1 percent (n=378) and 30.8 percent (n=275), respectively.

"In multivariate analysis adjusted for other predictors of mortality, system delay was independently associated with mortality, as was its components, pre-hospital system delay and door-to-balloon delay," the authors wrote.

"We conclude that healthcare system delay is valuable as a performance measure when patients with STEMI are treated with primary PCI, because it is associated with mortality, it constitutes the part of treatment delay modifiable by the healthcare system in the acute phase, and it applies to patients field-triaged directly to the PCI center as well as to patients transferred from local hospitals. Increased focus on the total healthcare system delay may optimize triage of patients with STEMI and may be the key to further improving survival of these patients."