Early data suggest new protocol to risk-stratify chest pain patients, potentially preserving resources without compromising safety
Serial troponin tests improve sensitivity of a risk-score system developed in Europe
May 1, 2015
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Executive Summary
Early data from the study of a new protocol suggest there may be a more efficient way to risk-stratify patients presenting to the ED with chest pain so that lower-risk patients can be safely discharged rather face longer hospital stays and expensive tests. The approach, dubbed the HEART Pathway, involves using the HEART score, a clinical decision tool developed in the Netherlands, along with slight modifications including a second blood test for troponin levels.
- Experts say that the United States spends $10 to $13 billion per year for workups on chest pain patients when fewer than 10% are actually having an acute coronary syndrome.
- In a single-center randomized controlled trial, investigators found that when compared to usual care, use of the HEART Pathway resulted in 12% fewer cardiac tests, shorter lengths-of-stay, and 21% more early discharges. No patients in either group experienced a major cardiac complication within 30 days of their ED visit.
- Larger studies of the HEART Pathway approach are being implemented with more robust findings expected within a year.
Emergency providers are accustomed to seeing patients with chest pain. In fact, it is the second most common complaint in the ED. However, while more than half of these patients are either admitted or placed in an observation unit for rounds of expensive tests, a cardiac cause is ruled out most of the time.
“It has been a frustration for most of us,” notes Simon Mahler, MD, MS, FACEP, an associate professor in the Department of Emergency Medicine at Wake Forest University School of Medicine in Winston-Salem, NC. “We do all of these workups. We spend somewhere between $10 billion to $13 billion per year on these patients … and less than 10% are actually having an acute coronary syndrome when they come to the ED.”
As Mahler further points out, though, even with all of this testing, there is evidence that providers still miss some patients who are having acute myocardial infarctions (MI). “We have had issues on both sides of the spectrum: over-triaging patients to testing and missing patients and sending them home when they should have been tested.”
While this has been a vexing problem facing emergency providers for years, there is growing evidence that accuracy on these matters can, in fact, be improved. And the latest indication of this comes from a new study, led by Mahler, showing that there is good potential in a protocol called the HEART Pathway to accurately identify those lower-risk patients who can safely be sent home without the additional testing that typically takes place now.
Early data show promise
The HEART Pathway adds a couple of modifications to the HEART score system, a widely used clinical decision tool that was developed and validated in the Netherlands. The HEART score takes into account five components, including the patient’s history, electrocardiogram reading, risk factors, age, and troponin levels, to determine an individual’s risk of having a serious cardiac issue. However, studies have shown that the HEART score alone isn’t quite sensitive enough to get the miss rate down to less than 1%, the minimum threshold deemed acceptable in the United States, observes Mahler.
To improve the sensitivity of the HEART score, investigators added a second blood test to measure troponin levels three hours after the first blood test, and they also added the modification that a patient cannot be considered low risk with any positive troponin result, explains Mahler.
Early testing of this HEART Pathway protocol revealed that the tool had 100% sensitivity in a cohort of patients that were admitted to an observation unit. “We were able to send home a larger number of patients from the observation unit cohort,” notes Mahler. “So the next thing we did was look at the HEART Pathway within a cohort of about 1,000 patients from 18 different EDs in the United States.”
The data came from a biomarker study, so researchers had the troponin levels and all the clinical assessment needed to calculate HEART scores on the patients. “We found that [the HEART Pathway] was 99% sensitive, and we could have discharged more than 20% of those patients,” explains Mahler. “We compared it to just clinician gestalt and we compared it to one of the other chest pain rules, and the HEART Pathway rule seemed to perform better.”
With all of this research completed, along with multi-center European trials showing that the HEART score alone produced a miss rate of about 1.7% over a six-week period, Mahler and colleagues decided they had enough evidence to start looking at the HEART Pathway prospectively in a randomized, controlled trial.
With funding from the American Heart Association (AHA), Mahler and colleagues set out to compare risk stratification using the HEART Pathway with usual care, according to AHA guidelines. The single-center study included 282 chest pain patients who presented to the ED, with half randomized to the HEART Pathway arm and the other half randomized to usual care.1
Evidence is growing
What the investigators discovered was that the chest pain patients evaluated with the HEART Pathway underwent 12% fewer cardiac tests, had shorter lengths-of-stay, and experienced 21% more early discharges than the usual care group. Further, no patients in either group experienced a major cardiac complication within 30 days of their ED visit.
While this was a small trial, Mahler says that the data, when combined with earlier studies on the HEART score, together represent strong evidence to support “the structured implementation” of the HEART Pathway protocol.
“The HEART score has been evaluated in more than 6,000 patients now, and we have evaluated the HEART Pathway using observational data in more than 2,000 patients, and then there is this smaller, prospective randomized study,” says Mahler.
While this is not enough evidence to go ahead and implement the HEART Pathway as a standard of care, according to Mahler, he believes that there are enough data to support centers that want to implement the protocol as long they are willing to closely monitor the impact, conduct quality surveillance, and make sure that they are not seeing any increase in adverse outcomes.
“That is exactly what we are doing at Wake Forest right now. We are just at the beginning of our implementation,” says Mahler. “We expect, after about a year, that we should have some pretty robust data of what it looks like with a structured implementation [of the HEART Pathway] across a health system [including] three sites.”
Hospitals, payers show interest
A number of other hospitals are proceeding with trials of the protocol as well. For instance, James McCord, MD, a cardiologist affiliated with Henry Ford Hospital in Detroit, MI, is looking at the HEART Pathway protocol within the scope of a small pilot study involving about 100 patients.
“We are just looking at people at the very low-risk score [end of the spectrum], and then we are randomizing them to immediate discharge vs standard of care, which is observation and mostly stress testing,” says McCord. “I think the biggest bang for your buck is just at that lower-risk end, sorting out who you can send home.”
McCord observes that it is clear that the second blood test for troponin levels, which is called for in the HEART Pathway protocol, adds important value in evaluating risk. “You can argue over what time period [is optimal] for doing the [second blood test], but the bottom line is it does look like for the best score, you do need to have some serial sampling of the troponins,” he says.
McCord also prefers the type of scoring used in the HEART score, from which the HEART Pathway is derived, over some of the other methodologies for assessing risk. “Probably the [risk score] that gets the most press in the United States is the TIMI [Thrombolysis in Myocardial Infarction] risk score or the modified TIMI score, but my take on that is that the TIMI score was really developed and meant to be used in definite MI patients, so its application to this category of patients is, in my mind, poor and questionable,” he observes. “When you actually try to apply that score to this [lower risk] patient population, it is not as predictive as the HEART score.”
While all of the risk scores base their findings on similar criteria, McCord notes that the HEART score has the most validation in the largest number of appropriate patients, but he does acknowledge that most of the studies on the clinical decision tool have taken place in Europe. “It is mostly novel in the United States,” he says. “I would assume the European studies are not much different, but sometimes you get surprised by results, so it has to be studied more [here].”
Nonetheless, McCord is intrigued by the HEART Pathway approach. “I think this has tremendous potential to help sort out who can go home from the ED without any further observation and testing,” he says. “It is promising, but this is preliminary data, and I believe it would be premature to implement such a protocol outside of a trial because it is certainly not the standard of care.”
Changing practice is challenging
Gregg Fonarow, MD, associate chief of the Division of Cardiology at the University of California in Los Angeles, CA, and an AHA spokesperson, is likewise impressed with the findings of Mahler’s HEART Pathway study. “It is a very nice single-center study that integrates a clinical decision support tool together with a standard troponin assay brought together to improve the identification of low-risk patients presenting with chest pain that could be discharged from the ED safely,” he observes. “It demonstrated less use of cardiac testing, a shorter length of stay, and those patients identified for early discharge did not have any cardiac events in the first 30 days.”
Speaking more generally about accelerated pathways for chest pain patients, Fonarow notes there are a number of tools that have been shown to be valuable in carrying out this type of risk-stratification. “There is really a growing body of evidence that this is an efficient, high-value approach to patients with chest pain who are identified through a validated risk score together with troponin assays to be low risk so that they can then be safety discharged from the ED without a more prolonged period of observation,” he explains.
Fonarow notes that UCLA has utilized an accelerated pathway for chest pain patients for years, but he acknowledges that it is challenging to change the way emergency providers typically manage these patients. “Missing a patient who presents with myocardial infarction can be absolutely devastating. It is one of the leading causes of liability for emergency medicine physicians, so there is a lot invested in the type of monitoring, additional consultation, and testing that has traditionally occurred,” he says. “In some ways there is a shared feeling of responsibility if you have observed the patient for a longer period, consulted a cardiologist, and performed stress testing prior to discharge.”
The extra time and resources devoted to these patients may help providers feel that they have provided additional safety for the patient and additional liability protection for themselves, but there are consequences, notes Fonarow. “This ends up being tremendously expensive with a large number of individuals that otherwise would be at low risk being kept in the ED or observation unit,” he says.
Mahler’s study, showing that use of the HEART Pathway protocol resulted in no patients being discharged when they really were having a cardiac event, is added evidence that accelerated pathways can be implemented into clinical practice, argues Fonarow. “Troponin testing is just getting better and better, and when combined with clinical decision support tools, it can help identify low-risk individuals more efficiently.”
Potential cost savings significant
Mahler observes that a more accurate and efficient approach to risk-stratifying chest patient patients offers value to all the stakeholders involved. “It is patient-centered because patients don’t want to have unnecessary hospital stays and to undergo unnecessary testing. There is anxiety and expenses related to those,” he says. “Then it can also save the health system a lot of money, and payers are excited about this sort of program as well.”
Mahler notes that two payers in North Carolina have been willing to share data because of the protocol’s potential to cut costs while still delivering high-quality care. “Hospitals are excited about this too. It was fairly easy showing them the data from this trial and the data from previous studies both in Europe and [the United States] — just to [demonstrate] that this is something we should be looking into further because the reductions in admissions are pretty profound, and then there are the decreased lengths of stay; and all of that translates into big cost savings.”
REFERENCES
- Mahler S, Riley R, Hiestand B, et al. The HEART Pathway Randomized Trial: Identifying emergency department patients with acute chest pain for early discharge. Circulation: Cardiovascular Quality and Outcomes 2015;8:195-203.
SOURCES
- Gregg Fonarow, MD, Associate Chief, Division of Cardiology, University of California, Los Angeles, CA. E-mail: [email protected].
- Simon Mahler, MD, MS, FACEP, Associate Professor, Department of Emergency Medicine, Wake Forest University School of Medicine, Winston-Salem, NC. E-mail: [email protected].
- James McCord, MD, Cardiologist, Henry Ford Hospital, Detroit, MI. E-mail: [email protected].
Emergency providers are accustomed to seeing patients with chest pain. In fact, it is the second most common complaint in the ED. However, while more than half of these patients are either admitted or placed in an observation unit for rounds of expensive tests, a cardiac cause is ruled out most of the time.
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