Q3: How should a hospital decide to select a 0h/1h, 0h/2h or 0h/3h algorithm, and linking to that, based on what criteria does the hospital select an appropriate assay?
The use of these protocols, regardless of whether the retesting is done at one, two or three hours, requires the availability of a high sensitivity troponin assay. If the hospital doesn’t have any, then they cannot apply the fast protocols.
Secondly, the assay must have been validated in a peer reviewed study; it must have been published and the protocol for its use must be clear. Then, if you have the choice to perform either retesting at one, two or three hours, I think that the hospital has to define whether there is a need to make the disposition of patient as fast as possible. If there is no need to discharge a patient because the hospital doesn’t have any overcrowding, then of course, you can go for a 0h/6h algorithm. But most hospitals in the world face overcrowding, and therefore, they appreciate a fast protocol.
I think you can use whatever you like, but in real life, it’s not always possible to go for retesting at exactly 60 minutes or retesting at 120 minutes – it depends on many factors like delays in the blood draw, the nurse is busy, the physician is busy. So, I like the idea of maximal flexibility. If the actual blood draw time is 91 minutes after the first sample, I use the 0h/2h protocol because it’s closer to two hours retesting than to one-hour retesting, and if you are more than 30 minutes beyond the tolerance margin for the two-hour protocol, then you have to apply the three-hour protocol. So flexibility, I think, is required, unless you have the infrastructure and you have installed some measures that ensure that you can always have blood drawn at fixed time points – that is something which is now recommended in the guidelines. For convenience and in order to disrespect or ignore the differences in turnaround times that may prevail in one or other hospital because they do not have the infrastructure for fast turnarounds, the guidelines promote taking the first blood draw early after admission, after presentation of the patient – don’t wait for the result of the first blood test, instead, go for the second blood test at exactly 60 minutes after the first, and when you have the results, you can interpret them together. So this is one approach.
Q4. Any new practical guidance on how to implement the ESC 0h/1h algorithm since it is the most recommended according to the ESC 2020 guidelines?
I think that people should start to use it. The fears that have been expressed against the use of these protocols, I think, are largely unsubstantiated. I think that particularly, the rule-out group benefits most from these very fast protocols because they are identified by low troponin concentrations and small concentration changes. So, this means they are ruled out from the presence of myocardial injury and that is not only a diagnostic finding, that’s also prognostically, a very relevant finding, because this is the group that also has a very small future risk for any ischemic or cardiovascular events. It’s biologically plausible that these patients can be discharged with higher confidence. It’s unlikely to develop an infarct, an on-going infarct or to suffer a major cardiovascular event within 30 days. And, of course, if you discharge the patient, that does not mean that you fire and forget. You have to continue some tests after discharge. They can see a practitioner and if possible, they should have a post-discharge or, even better, a pre-discharge stress test, and they should have imaging and echocardiography. Except for a very low-risk patient, as recommended in the current guidelines, I think forget about what you heard about missed myocardial infarction and the threat of dying after being discharge, I think, in reality, the event rates are very, very low, as compared to the previous 0h/6h to 0h/9h strategies.
The recommendation to take two blood samples one hour apart without waiting for the results of the first blood draw will probably cost more because maybe, in 20 to 30% of cases, you draw an unnecessary second blood sample that could have been avoided if you had known the first blood sample is very, very low. Nevertheless, the advantage of having this fixed sample interval is that you do not depend on long or excessively long turnaround times. We know that the infrastructure at some hospitals is inappropriate to ensure a turnaround time is within 60 minutes. It may sometimes take one and a half or two hours. If you have real pressure in your emergency department, then you may want to accelerate the disposition of patients. Then, I think, it’s a trade-off if you like to invest a little bit more money in order to release, to discharge, or admit more patients from your emergency department. In many countries, I think that makes sense as it’s economically effective. In other countries, maybe they prefer to wait, but then the effectiveness of the 0h/1h protocol diminishes.
