Improving the patient pathway for suspected ACS: How point of care high-sensitivity troponin testing could help

I’m Rick Body. I’m a professor of emergency medicine and the University of Manchester and I’m a consultant in emergency medicine, practicing doctor, at Manchester University NHS Foundation Trust.

So cardiac troponin is absolutely essential to making clinical decisions about patients with suspected acute coronary syndromes in the emergency department. I’d say there are three crucial pieces of information that were going to gather from those patients. One is our clinical assessment, and arguable that’s actually the most important thing, because you can’t actually interpret cardiac troponin without the clinical context - so that’s your patient history, your physical examination, vital signs. And then you’ve got the ECG and that tends to be our investigation of first choice, we do that when patients first come to the emergency department because we can rapidly rule in ST elevation myocardial infarction for some patients, and they can go off and get immediate revascularization without further ado. And finally, there’s the cardiac troponin concentration.

Now in practice, we probably reverse engineer that pathway. We do the ECG first because we get that information quickly, and then we tend to take blood for the cardiac troponin concentration, and that’s largely because the turnaround time of the test is so long that we want to reduce the waiting time after the patient’s seen the clinician to reduce the time that it takes to actually be able to make a clinical decision about the patient. And the last thing we will do is make a clinical assessment.

The key benefit of point of care high sensitivity troponin testing will be that we get a reduced turnaround time. It takes less time to get the result – 10 or 20 minutes as opposed to one hour in a lab. But we’ve also got to think about the vein to brain time. It may take only one hour to get the lab result, but actually in effect it takes more like two hours to get the information into the clinician’s brain for them to be able to make a clinical decision. Because we’ve got all of the pre-analytics, the time take to get the sample to the lab and the time that it takes for the clinician to realize that the result is available and act upon it. So, with more rapid results we can make more rapid decisions and we can unburden crowded emergency departments. And that’s a really, really key issue because it will reduce patient safety in this incident, and we know that crowding is associated with even an increase in patient mortality. Another benefit is that it actually allows us to redefine care pathways and start to deliver care in more patient centered, more community environments as opposed to hospital emergency departments. So, patients can have testing at urgent care centers, ambulatory care units, potentially in ambulances and potentially even in their own homes, someone can go out to them. Rather than requiring them to go to busy emergency departments and wait for laboratory diagnostics. The possibilities really could revolutionize how we care for patients with suspected acute coronary syndromes.

When you’re finding your pathway for point of care high sensitivity troponin testing, the first thing to think about is how are you going to look after these patients? Are they going to be looked after in out type one emergency department or are you going to take advantage of opportunities to move the testing to other environments like urgent care centers for example or a specific chest pain unit? Because this does give you that opportunity. Then you’ve got to think through the detail; so, who’s going to do the testing? When you do a laboratory test all you’ve got to do is collect the blood sample and send it to the laboratory and the biomedical scientists will take care of the rest. Now with point of care troponin testing you’ve got to think about, well how do I train my staff to look after the point of care troponin testing? How do we make sure that there are appropriate incentives for them to realize that this is actually in everyone’s interest to get the testing done? It’s an extra job for them but of course it’s going to have benefits for the emergency department and for the patients in the pathway. Another thing we’ve got to think through is how do we actually capitalize on this reduced turnaround time? So, it’s no good if you do your troponin test and then allow you patient to wait in a queue for an hour or two to be seen by a clinician. If that happens you’ve lost all of the benefits of the rapid turnaround time. You’ve got to think about - well, how do I get the patient out of that queue? - so that when they’ve got information available that allows me to make clinical decisions, we immediately act upon that. And that might be about redefining the chest pain pathway - so potentially for example bringing patients out into chest pain units and thinking about queues in a different way – not just who came in first but who’s got enough information for me to make a decision about their care.

One of the most exciting things about point of care troponin testing is the possibility we might be able to use fingerstick sampling rather than whole blood venous sampling. That’s for a few reasons; first of all, it makes it easy to test in rapid throughput settings. So, during triage for example when you’ve got large numbers of patients coming through, it’s far easier and faster to get a fingerstick sample than it is to get a venous blood sample from patients. It’s also better for patients because, you know, if you’re for example running this test in patients who are in pre-hospital environments, so they’ve just come in from outside, they’re sick and feeling unwell so they might be peripherally shut down, it’s not always easy to get a vein, it’s not a very pleasant experience the patient’s having repeated attend at venipuncture. So fingerstick sampling can get around that. And there’s one really nice potential by-product of this as well. It might help us to cut down on unnecessary lab testing. You’d lose all the benefits of point of care troponin testing if you send off unnecessary lab tests and have to wait for the results to come back - and that’s going to take you one or two hours - you’ve lost the benefit of the rapid turnaround time. With fingerstick sampling, you’re really going to have to focus in on what’s most necessary to make your clinical decisions, which might reduce the use of unnecessary lab tests and thereby improve patient experience, improve patient flow and help you to make more rapid decisions without losing any value.