Mortality Risk in STEMI Patients Linked to Slow Transfers

Nearly 90% of patients with a severe type of heart attack called a "STEMI," who go to hospitals that lack catheterization capability, have a 56% higher risk of mortality when they aren't transferred to a suitable hospital within the recommended 30 minutes.

Additionally, if the patient doesn't leave the first hospital within 90 minutes, the risk of inhospital mortality doubles.

Those are conclusions from an analysis of outcomes for 14,821 patients with an ST Segment elevation myocardial infarction (STEMI) form of heart attack who went to one hospital first, but had to be transferred to receive a percutaneous intervention or PCI to unblock a coronary artery.

"A lot of our efforts have focused on inhospital process to facilitate reperfusion (of blocked arteries), or on door-to-balloon time," Tracy Wang, MD, of Duke University School of Medicine and the report's principal author said in a telephone interview.

"But we're trying to pay more and more attention to those patients who first come to a non-PCI hospital or a hospital that doesn't do round-the-clock PCI, to see how we can expedite the transfer of these patients" in order to provide life-saving care and avoid heart muscle damage," she said.

The study is published in today's Journal of the American Medical Association. It focuses on a relatively new term in heart care called the DIDO, a metric developed in 2008 by the American College of Cardiology/American Heart Association to indicate the time between the patient's entrance to the first hospital, or door in, to the time they left it for the hospital with the cath lab, or door out.

The new metric is even more important, in some ways than traditional door-to balloon process measures because 75% of hospitals in the United States currently do not have the ability to immediately perform the procedure or perform it promptly, perhaps because of a lack of adequately trained interventional cardiologists. Those patients all must be transferred if they don't receive a thrombolytic first.

In fact, the median between the time the patient entered the door of the first hospital to the time the patient left that hospital for another was 68 minutes. Approximately 58% of the patients in the study had a DIDO time of greater than 60 minutes and 35% more than 90 minutes. That meant that getting that patient reperfused within the current ACC/AHA guideline of 90 minutes from the time they entered the first hospital was impossible.

"That's pretty remarkable," Wang said.

That's the window of time within which patients with this type of especially lethal heart attack, which is sometimes called a tombstone because of the way it appears on an EKG, need to have blood flow restored to avoid higher rates of risk-adjusted mortality.

Unfortunately, Wang says, networks of hospitals that have adequately organized paramedics and transfer protocols for these severely ill patients are few and far between.

"I wish we could have more of these networks around, because the fact that only 11% of these patients get out the door of the first hospital tells me we have a lot of improvements to make in terms of facilitating transfer of care. We know getting a DIDO of 30 minutes or less is achievable and reasonable."

While the number of hospitals and regions in the country that have organized regional heart attack transfer systems is still low, it is growing, and Wang believes that is the reason that over the course of the study period between 2007 and 2010, average DIDO times dropped.

"However, I think we still have a long way to go," she said.

The study represented hospitals in all states except Alaska, and included small rural hospitals as well as large urban acute care facilities. It included patients who arrived at the hospital by paramedic transport as well as patients who arrived by car and had to be transferred by ambulance to the second hospital.

An important finding in the study was that older, sicker patients – those who need faster catheterization procedures the most – waited longer to be transferred than younger healthier patients. Yang said that may have been because they may not have been stable enough for transfer.

The issue of hospital-to-hospital transfer of heart attack patients for appropriate catheterization is an emotionally charged one among emergency physicians and cardiologists around the country, especially in areas that lack ambulances equipped with 12-lead EKG machines that can distinguish chest pain patients that are having a true STEMI.

The practice throughout the country where there are no STEMI receiving centers is for ambulances to take patients to the closest hospital first for diagnosis and triage, rather than to one with a certified, round-the-clock catheterization lab with qualified board-certified interventional cardiologists.

Yang and co-authors wrote that their study "is the first to our knowledge to show a significantly higher mortality risk associated with a DIDO time greater than 30 minutes that persists after adjusting for many of the clinical and presenting features that contribute to myocardial infarction mortality risk."