Cardiac troponin is a critical biomarker for acute coronary syndromes (ACS). In the final session of this two-part webinar series, Dr. Frank Peacock, emergency physician, professor of emergency medicine, and vice chair for research at Baylor College of Medicine, describes how high-sensitivity troponin assays can aid the rapid disposition of patients with suspected ACS, the importance of time in and care in the emergency department (ED), and the impact point of care may have in improving clinical outcomes and operational efficiencies.
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Attendees to both events are entitled to P.A.C.E. credits from the ASCLS and/or ACCENT credits from the AACC.
FP: The short answer is sometimes. If your high-sensitivity troponin is high, that's called a myocardial infarction (MI), and you don't need a risk score, you've already got it within the troponin. If your high-sensitivity troponin is really low, you don't need a risk score, you need to go home. This is where high-sensitivity troponin is valuable. Then there’s the group that is not really high and not really low, where you have a clinical decision to make.
Below the 99 percentile and above the low-risk cutpoints is the cohort where risk scores are valuable, and the objective is to send as many people home as safely as possible. Our biggest worry is hurting somebody, so we’re not going to send somebody home who's on the fence. What the risk scores do is they essentially move the fence to help you make decisions and discharge more people safely.
FP: The people with chest pain that don't have ACS still have chest pain. And if it is because of another pathology, you don't get a pass, you still have to work on it. If they have pleuritic chest pain, you might want to consider pulmonary embolism. In that case, you decide based on risk. If they're high risk, you just go ahead and get a CT angiogram. But if they're low risk, you might want to consider a D-dimer.
That's not going to help you much with cardiovascular pathology, but with pulmonary embolism or deep vein thrombosis, it's really useful. There are not a lot of other good cardiology markers that help in the emergency department for decision making, but there are lots of other markers that you might use, and there's also stuff like vital signs and clinical markers as opposed to lab-based markers. But strictly for MI, yes or no, troponin is the one.
You might also want to consider the renal function and the presence of heart failure. Those are two known conditions that will have stable elevated troponins. They're not really sky-high like an MI, but they'll be up a little bit. I call it the 105th percentile. For those patients, it's really helpful if you know what their baselines are because if the troponin I is a little bit up today, they're not having an MI. You may decide you need to keep them in anyway because their renal failure is so bad that it's killing their heart. But that's a different decision.
FP: One size does not fit all, and you have to know which troponin I you're using. I presented several different algorithms that are used. Each one is specific to an assay. Whatever assay you’re using, you have to know the data specific to it. For example, when I presented the Siemens assay, if it's less than three in an hour, you're done. But that's not the same for all the other assays out there.
FP: One of the challenges in this field is that there are no high-sensitivity troponin point-of-care devices that the FDA has approved that are currently available. So the answer is none, but this is changing. It's in the near future and the market will be changing because every company that makes a troponin assay would like to have a point-of-care platform. There are a lot of advantages to point-of-care testing. I can say with some confidence that every company is working on this and the next big breakthrough we have in emergency medicine is going to be high-sensitivity troponin on a point-of-care platform.
FP: The homogeneity problem is that the cutpoints all have to be the same. In the era of lab information systems and computer printouts, it's really straightforward – you should just get that cutpoint printed on your lab sheet. The other reality is clinicians rarely work in just one place. My group and I have to cover four different hospitals and these don't all have the same troponin assay, so we're used to looking at every different result with every possible parameter. Whatever assay you have, the cutpoints should be next to the result on the printout. There's no question because it would be a disaster to apply the cutpoint of one troponin to another platform that it wasn't designed for because you could miss an MI and send them home, and that would be terrible.
There has to be some attention to the homogeneity issue in terms of the results being reported at a hospital, but it can be done in that fashion, working with the lab information system to clearly present the data to the clinicians.
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