“Time is muscle,” as the saying goes, and if new research is any indication, it may be possible to save more heart muscle by training emergency personnel to interpret electrocardiograms on the scene.
The study in the Canadian Journal of Cardiology said using EMTs to read ECGs can keep the critical time from first medical contact to treatment for patients with ST-segment elevation myocardial infarction (STEMI) within benchmark guidelines. (Can J Cardiol 2012;28:423.) A 2005 audit of Manitoba hospitals found that only 14 percent of STEMI patients were given thrombolytics within 30 minutes of first contact, and only 11 percent received primary percutaneous coronary intervention within the recommended 90 minutes of first contact.
A team at the University of Manitoba worked with emergency medical personnel to develop CODE STEMI (Cardiac Outcomes through Digital Evaluation STEMI), a prehospital ECG interpretation and triage system. Emergency medical technicians were trained in how to perform and read ECGs for signs of STEMI.
Emergency personnel transmit the ECG to an on-call physician using a handheld device when STEMI is suspected. Once the physician confirms the STEMI findings, he directs EMS personnel to administer prehospital thrombolytics or alerts the cath lab.
The researchers identified 226 STEMI patients during the first two years of CODE STEMI. Patients receiving thrombolytics had an average time from first contact to therapy of 32 minutes; patients receiving PPCI had an average time to therapy of 76 minutes.
The program increased STEMI patients receiving thrombolytics within 30 minutes to 35 percent (14 percent before CODE STEMI). But the really impressive numbers were found in the PPCI category: 76 percent of patients needing angioplasty received it within the 90-minute window, compared with just 11 percent prior to CODE STEMI.
“These figures may actually underestimate the level of improvement,” said lead researcher Robin Ducas, MD, a cardiology fellow at the University of Manitoba. “With greater paramedic involvement in 2010, more patients received prehospital care and early therapy than in 2004–2005.”
Dr. Ducas and her team found in a related study that EMS interpreted the ECG results as negative for STEMI and did not transmit the ECG to the physician for 323 of 703 chest pain cases, although the patients were still taken to the emergency department. Fifty-two percent of those cases were diagnosed with nonspecific chest pain and later discharged. One case of STEMI was missed, and two patients developed STEMI after arriving at the hospital.
The ECGs for the other 380 patients were interpreted as positive, and the physician suspected STEMI in 226 of the cases, 96.9 percent of which were later confirmed, leaving seven false-positive cases. The physician missed a STEMI in seven cases.
The false-positive rate was relatively small, but Dr. Ducas acknowledged that even a few false-positives can present a significant problem — a risk of complications for patients given thrombolytics needlessly and unnecessarily activating the cath lab, which is costly and could impair care for others. “We do want to err on the side of caution because you don't want to miss a STEMI,” she said. “But you must balance sensitivity with specificity. We're happy with the rate we have. If you get your rate of false positives to 0, you'll be missing cases.”
A project like CODE STEMI can be “an extremely valuable tool,” said Henry Wang, MD, an associate professor and the vice chair for research of emergency medicine at the University of Alabama-Birmingham. An early version of a similar program was launched in the late 1990s at Christiana Care in Delaware, where he received his residency training. It was also been found to reduce time to PPCI significantly. (Ann Emerg Med 2009;53:233.)
“In my own practical experience, paramedics are extremely able to read 12-lead ECGs,” he said. “I would be very comfortable activating cath lab resources based on remote reports from EMS. But you need a program with intensive training and close oversight.”
Dr. Ducas agreed, noting that the system needs a lot of buy-in. “The EMTs, the cath lab, the CODE STEMI physicians [who are cardiologists and emergency physicians], and the hospital residents must all be on top of things,” she said.
Dr. Ducas' study did not measure survival benefits accruing from the accelerated time to intervention, and she said a larger study might be able to tease out those numbers. Dr. Wang cautioned, however, that the real scope of the benefit from such diversion programs remains unclear. He and colleagues at the University of Pittsburgh conducted a decision analysis and simulation study in 2009 to assess the benefits of transporting patients with a STEMI directly to a center with a cath lab rather than to the nearest community hospital. Utilizing North American clinical studies of STEMI and chest pain care published after 2001, Dr. Wang assessed whether direct transport of STEMI patients to a PPCI center, rather than to the nearest community hospital providing fibrinolytic therapy, actually improved 30-day survival rates.
The findings weren't what would be expected. Thirty-day survival was higher for standard percutaneous coronary intervention than standard community hospital fibrinolytic therapy (95.8% vs. 93.8%), but lower when compared with best-case community hospital fibrinolytic therapy (95.8% versus 97.8%). “Going straight to the more-distant cath lab does not always win in terms of 30-day survival,” he said. “When it does win, the survival gains are sometimes small.”
Dr. Wang hastened to add that he was not saying that going directly to a cath lab with a STEMI is a bad strategy. “It's optimal care,” he said, “but in certain scenarios, there could be very formidable logistical barriers, and direct transport to a distant cath lab may not be the best strategy.
Regionalization to the Rescue
Legislative pressure and financial strain will drive emergency medicine toward more collaboration. Read more in our Special Report, p. 18.