The mortality rate of patients with undetected acute myocardial infarction (AMI) is at least twice that of patients who are accurately diagnosed. Prompt, accurate diagnosis is critical. The key, according to the Society of Chest Pain Centers (SCPC), is to “reduce time to treatment during the critical early stages of a heart attack, when treatments are most effective, and to better monitor patients when it is not clear whether they are having a coronary event.”
Hospitals achieve the best outcomes when they establish evidence-based protocols to rapidly diagnose and treat AMI. These protocols should be deployed by a diverse team of professionals, including physicians in emergency medicine and cardiology, nurses, and quality improvement leaders. Every step of the process must be carefully thought out and implemented correctly, efficiently and in a timely manner.
The practice of medicine “has become a team sport, beyond any one physician or one person,” explains Raymond Rodriguez, M.D., a board-certified interventional cardiologist who serves as medical director of Mount Sinai Cardiology in the Keys of Florida, an assistant professor of medicine at the Columbia University Division of Cardiology at Mount Sinai Medical Center in Miami, and a HealthTrust physician advisor. “You need an evidence-based protocol and a coordinated team in order to deliver the best outcomes.”
Door-to-balloon Time: The Critical Metric
An accurate history, physical exam and electrocardiography (ECG) are typically the first steps in any AMI protocol. ECGs performed by paramedics in the field are helpful for early notification to the hospital.
“I would like to see paramedics focus on getting patients into the hospital as fast as possible and the ED doctors focus on getting patients to the cath lab quickly,” says Richard Heuser, M.D., chief of cardiology, St. Luke’s Medical Center and Phoenix Heart Center in Phoenix. “Classic ST-elevation on ECG is the diagnostic marker of STEMI. With NSTEMI, diagnosis is a little more challenging. ECG, patient history of presentation, ongoing pain, or unstable vital signs will indicate which patients need to go to the cath lab.”
Even an ECG may not be as valuable as hospitals think. “The ECG represents an instantaneous moment in time; therefore, a single ECG may not accurately represent the entire picture,” says Felix Lee, M.D., medical director of the cardiac cath lab at HCA’s Good Samaritan Hospital in San Jose, California. Lee also serves as cardiovascular service line physician advisor for HealthTrust and physician lead for HealthTrust’s recent Collaborative Summit on Managing AMI Patients.
For NSTEMI, troponin is the biomarker of choice when the ECG doesn’t tell the whole story. The goal is to get the results of these tests and get the patient to the cath lab as swiftly as possible for diagnostic coronary angiography, percutaneous coronary intervention (PCI) or other therapy to follow.
Critical diagnostics can be performed in the ambulance or in the emergency department (ED). “Health systems decide their protocol,” Heuser says. “Some systems have the paramedic in the ambulance or in the field to administer the ECG, and possibly measure troponins. These are sent to the hospital so doctors have the information prior to the patient’s arrival.”
Rodriguez’s goal is to get the ECG within 10 minutes of the patient coming to the ED and have a door-to-troponin within 60 minutes of patient presentation. “Timeliness matters, and has to be a part of every ED’s protocol, especially with AMI, since time is muscle, which is life,” Rodriguez says. “Every staff member—from greeters and registrants to nurses and physicians—should be working to get these vital pieces of information in a very timely fashion.”
Matthew Bilodeau, M.D., Ph.D., an interventional cardiologist practicing with Lutheran Medical Group in Fort Wayne, Indiana, and a HealthTrust physician advisor, agrees that hospitals should have a standardized chest pain protocol—whether it’s a facility like Lutheran that has a cath lab or an outside hospital where patients receive thrombolytic therapy with the intention to transfer them as soon as possible.
Lutheran’s protocol stresses rapid transfer to the cath lab once the patient arrives, and metrics are tracked closely. The ED avoids administering any diagnostic or intervention that could delay transfer to definitive treatment, which is almost 100 percent PCI-based. The hospital rarely uses thrombolytics, except in situations where either the patient’s condition prevents transfer in a timely manner or the receiving facility is located too far away.
Life-saving New Technologies
At Lutheran, interventional coronary care has expanded, based on new technologies known to improve outcomes. Bilodeau explains, “We’re fortunate to have access to technologies that are really coming of age, such as percutaneous ventricular assist devices, for patients who present with cardiogenic shock or out-of-hospital cardiac arrest.”
“Patients who are resuscitated, usually in the field, and find their way to the cath lab may then be eligible for additional care coordination aimed at protecting them from the brain injury that sometimes follows these kinds of events,” Bilodeau explains. “We use newer technologies, including a hypothermia protocol, which we have readily available in the cath lab for more rapid and effective cooling of patients, as well as for rewarming them when the protocol is complete.”
Bilodeau is pleased that Lutheran has these technologies available for specific patient populations that are at highest risk for mortality. “Evidence seems to support both improved outcomes and sur-vival to discharge, as well as quality of life down the road,” he says.
On the near horizon are noninvasive sensors to help physicians diagnose AMI much earlier. These sensors, which are not ECG-driven but rely on other physiological measurements, such as heart-type fatty acid-binding protein (or H-FABP), could change the dynamic of who makes the diagnosis. Many emergency departments and chest pain centers already use computers capable of continuous ST segment monitoring.
According to Bilodeau, one of the biggest challenges is reducing unnecessary delays in care by integrating the ED with the local emergency medical system, especially with AMI referrals from outside hospitals. “Sometimes there’s a delay in transferring the patient because an ambulance isn’t available or stationed at the hospital, and some of those hospitals are not even that far from us,” he says.
Team readiness is another critical factor. Heuser suggests that 15 minutes after the hospital receives a call, half of the team should be at the hospital waiting for the patient. He believes this process could probably reduce door-to-balloon time on a normal case by 20–30 minutes. “We perform quality assurance reviews on all AMI cases, including any door-to-balloon times greater than 90 minutes,” Heuser reports.
For Rodriguez, the huge gaps are in prevention and outreach. “Hospitals need to become more welcoming and familiar places, not the places people go to only if near death. We can do a better job of educating people about AMI symptoms so they’ll recognize when they should come to the hospital.”