Research shows practice cuts door-to-balloon times significantly
Patients having ST-segment elevation myocardial infarction, or STEMI, heart attacks have the best chance of a good outcome if they get primary percutaneous cardiac intervention (or "angioplasty") within 90 minutes of arrival at a hospital, recent research confirms. Because all hospitals don't operate cath labs-or can't perform PCI 24/7 ƒ some EMS systems now have protocols that allow paramedics to take patients directly to hospitals that can. Some of those systems also allow an emergency physician (instead of a cardiologist) to activate the cath lab based on a prehospital electrocardiogram.
And recently, a few progressive hospitals and EMS systems began allowing paramedics to activate the cath lab directly after they do a prehospital ECG and diagnose a STEMI.
Last June, Cypress Creek EMS, a large combination ALS service in north suburban Houston, began a new STEMI Alert program that allows paramedics to activate the cath lab at Houston Northwest Medical Center, the primary CCEMS receiving hospital. "We've had 41 activations and no false activations," said Wren Nealy, CCEMS director of special operations. "We don't transmit our 12-leads to anybody."
According to Nealy, the hospital door-to-balloon time for those patients averaged 47 minutes and only 87 minutes from when the 9-1-1 call was answered until the patient received a PCI.
"In the past month, we had four patients in cardiac arrest at the time of paramedic arrival," he said. "The paramedics got return of spontaneous circulation, provided a 12-lead ECG, detected a STEMI and all four bypassed the ER and went straight to the cath lab. All four are now alive and fully neurologically intact." He notes that one of those patients got PCI just 17 minutes after CPR.
According to Nealy, CCEMS paramedics went through training in the HNMC cath lab with a cardiologist and learned to perform the necessary evaluations, assessments, etc., to "prep" a STEMI patient for a PCI. "The national goal is 90 minutes door-to-balloon time because the ER must do all the prep, but we do that in the ambulance."
So far, Northridge (Calif.) Hospital Medical Center is the only Los Angeles-area hospital to go that far. That hospital even invites paramedics who activate the cath lab to accompany the patient to the lab and observe the PCI, according to Ivan C. Rokos, MD, an emergency physician at Northridge and assistant professor of clinical medicine at the University of California, Los Angeles.
Rokos was lead author on a paper published last October that describes the rationale for regional STEMI networks (Rokos IC, Larson DM, Henry TD, et al: "Rationale for establishing regional ST-elevation myocardial infarction receiving center (SRC) networks."American Heart Journal. 152:661-667, 2006). "A 'grassroots' movement has begun to develop, in which a variety of EMS systems across the nation have independently begun to implement some type of regionalized primary PCI for STEMI," he and his co-authors from Los Angeles, Minnesota and North Carolina noted.
According to Rokos, EMS systems in urban areas nationwide, including Atlanta; Boston; Minneapolis; Durham, N.C.; Portland, Ore; San Diego; and Orange County, Calif., now have SRC networks, and he expects to see them proliferate.
Los Angeles County launched a regional SRC network Dec. 1, 2006, with three hospitals on board. A dozen hospitals had joined the network by Jan. 1, and more than 20 of the county's 75 acute care hospitals have applied to be SRCs, according to Rokos.
"If they are a STEMI-receiving center, they can either activate the cath lab blindly based on EMS [interpretation of an ECG] or they can get transmission of the prehospital ECG," he said.
Boston EMS has taught its 62 paramedics to interpret an ECG "manually"; and in a study, they performed as well as a "blinded" emergency physician and a cardiologist who reviewed their prehospital ECG readings (Feldman JA, Brinsfield K, Bernard S, et al: "Real-time paramedic compared with blinded physician identification of ST-segment elevation myocardial infarction: Results of an observational study. American Journal of Emergency Medicine. 23:443-448, 2005).
"But we have 2,500 paramedics [and 27 provider agencies] in L.A. County," Rokos said, "And obviously we can't train everyone to read ECGs." So Los Angeles County has paramedics rely on an automated computer ECG interpretation. "All they have to do is read ***Acute MI, and that's their ticket to go," he said.
Research shows 50% of STEMI patients arrive at a hospital via ambulance. Those who walk into an emergency department at a hospital without a cath lab may require a rapid interfacility transfer via ground or air ambulance.
D2B Initiative & EMS
Because most STEMI patients in the United States currently do not get primary PCI within 90 minutes, the American College of Cardiology and American Heart Association launched a national Door-to-Balloon Time (or D2B) Initiative in November 2006 to help hospitals achieve the 90-minute goal.
Hospitals that join the D2B Initiative must implement six strategies that studies show reduce door-to-balloon time significantly: Î An ED physician activates the catheterization lab.
They are also offered an optional strategy: prehospital activation of the cath lab.
"Hospitals with the capacity for pre-hospital ECG should fully utilize this evidence-based strategy," the D2B Alliance states. "However, participation in D2B will not be contingent upon implementation of this strategy due to its resource implications."
To come up with those strategies, researchers surveyed 365 acute care hospitals on their STEMI strategies and found those practices that significantly improved D2B time (Bradley EH, Herrin J, Wang Y, et al: "Strategies for Reducing the Door-to-Balloon Time in Acute Myocardial Infarction."New England Journal of Medicine. 355:2308-2320, 2006). Having an ED activate the cath lab while a patient was en route was the second most successful strategy, cutting D2B time by 15.4 minutes.
"Good EMS systems already know this intuitively, and national guidelines recommend prehospital ECGs," said Elizabeth Bradley, PhD, professor of public health at Yale School of Medicine, lead author of the study in the New England Journal of Medicine, and a member of both the D2B evaluation team and the D2B Alliance. "But it's not enough to do the prehospital ECG; it must be faxed or [otherwise] transmitted to the hospital, and the hospital must be responsive to it.
"Knowing you're really going to get the times down if you take the step to activate the lab based on the prehospital ECG, we spent a lot of time discussing this. But ultimately, the D2B leaders decided to keep the prehospital component as 'optional,' so it wouldn't deter hospitals that couldn't or wouldn't take that step from participating," said Bradley.
Rokos, the American College of Emergency Physicians liaison to the D2B Alliance and a member of the D2B task force, hopes to start a parallel EMS ECG-to-balloon time-initiative, or E2B, to build on the foundations of the D2B Initiative. He's drafted an E2B Prehospital Training Module and is promoting the idea with D2B leadership and within the L.A. County SRC network.
So far, only Northridge Hospital has "embraced the E2B challenge," he said. "Our hospital E2B plan is the newly developed 30-30-30 rule: 30 minutes from field ECG to hospital door, 30 minutes [from] ED door to cath lab door and 30 minutes [from] cath lab door to balloon."
According to Bradley, some hospitals without PCIs resist having paramedics bypass their facilities with STEMI patients, and "some hospitals with PCIs don't think EMS-or even an emergency physician-can reliably decide if they have a STEMI patient and [worry] they may call in false alarms.
"It used to be that only a cardiologist could diagnose STEMI and activate the lab," she said. "That's now moving to the ED physician, but we're pushing even farther and asking them to trust EMS." She notes that hospitals that now allow EMS to activate the cath lab "started with the ED physicians, so the stepwise fashion is pretty effective."
"I think there's a message here for EMS systems," Bradley said. "Most paramedics I've worked with like to learn new skills, and when they're sitting there with a patient infarcting, they want to do more."