Timely Treatment of STEMI Patients Transferred for Primary PCI Still a Problem

Even when the estimated transfer time is less than an hour, 1 in 3 US STEMI patients referred to another center for primary PCI do not meet the recommended first door-to-device goal of 120 minutes or less, according to a study published in the May issue of Circulation: Cardiovascular Interventions.

“We can’t explain the gap in achieving this quality initiative based on distance of patients to primary PCI centers or long travel distances,” study author Harold L. Dauerman, MD, of the University of Vermont Medical Center (Burlington, VT), told TCTMD in a telephone interview. “There are other processes that are continuing to limit the transfer process.”

Using the National Cardiovascular Data Registry Acute Coronary Treatment and Intervention Outcomes Network (ACTION) Registry-Get With The Guidelines database, the researchers studied 14,518 STEMI patients transferred from non–PCI-capable hospitals to centers equipped for PCI from July 2008 through December 2012. The analysis excluded patients with estimated transfer times exceeding 60 minutes based on Google Maps–estimated driving times.

The median estimated transfer distance was 26.5 miles, and the median estimated transfer time was 33 minutes. Most patients (75%) used self-transport to get to the initial hospital—meaning that first medical contact was essentially the same as first door time—and only 11.3% received a prehospital ECG.

About two-thirds of patients (65%) achieved a first door-to-device time of 120 minutes or less, the goal recommended by American College of Cardiology/American Heart Association guidelines. Even after risk adjustment, however, only 37% of hospitals had at least 75% of their transferred STEMI patients meeting that target.

On multivariate analysis excluding cardiogenic shock, cardiac arrest, and door-in/door-out (DIDO) times at the referring hospital—which are known contributors to delayed reperfusion in transferred patients—numerous factors predicted a treatment time exceeding 120 minutes. The most powerful predictors of delay were left bundle branch block (LBBB) at presentation, isolated posterior MI, prior CABG, and presentation in the Northeastern vs Southern United States. The factors most strongly associated with a greater likelihood of achieving the target time were white race, high annual STEMI volume at the PCI hospital, and presentation in the Midwest vs South (table 1).

Further analyses confirmed that cardiogenic shock, cardiac arrest, and longer DIDO times are tied to reperfusion delays.

In a multivariate model incorporating DIDO times, the predictors of treatment delays remained largely similar to those from the initial analysis. Specifically, patients with prolonged DIDO times were 34% less likely to achieve the recommended first door-to-device time of 120 minutes or less. On the other hand, every 50-patient increase in PCI hospital annual STEMI volume was associated with a 25% greater likelihood of achieving the recommended timing.

Where to Focus Improvement Efforts 

Prior studies have also shown that about one-third of transferred STEMI patients do not achieve the recommended first door-to-device time. Those analyses, however, were not limited to patients with realistic estimated transfer times “and thus may underestimate the potential for timely transfer of appropriate patients,” Dr. Dauerman and colleagues write.

The current study, which focused on patients most likely to have transfer times conducive to achieving the goal, provided a similar result, which has “implications for clinical care and quality improvement,” the authors say.

According to Dr. Dauerman, there are 2 options moving forward. “Option 1 is to say it’s impossible to improve this any more and that for patients where you expect the transfers to lead to door-to-device times of greater than 120 minutes, pharmacoinvasive therapy is an [alternative] to be considered,” he said.

Citing the high percentage of patients who get to the initial, non–PCI-capable hospital on their own, Dr. Dauerman said the second option would involve focusing on having these patients picked up by emergency medical services (EMS) and given prehospital ECGs to either bypass non-PCI centers altogether or expedite the transfer process.

Further research is needed, he said, to determine why PCI hospitals with greater annual STEMI volumes are more likely to get transferred patients treated within 2 hours. “It may be that the answer here isn’t [to have] more primary PCI programs but in fact fewer primary PCI programs—to have more focused centers of excellence that can work with the non-PCI centers to expedite the transfer process and begin the triage process with EMS and a prehospital ECG,” he said.

Dauerman HL, Bates ER, Kontos MC, et al. Nationwide analysis of patients with ST-segment–elevation myocardial infarction transferred for primary percutaneous intervention: findings from the American Heart Association Mission: Lifeline program. Circ Cardiovasc Interv. 2015;8:e002450.

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