DR. GRANGER: I’ll just say, Peter, I think your point is also important not only for EMS, but for the first hospital that a patient arrives at with an ACS to have as a priority to give a P2Y12 antagonist for at least patients with the clear-cut diagnosis. I’m going to ask Tim, because there is controversy here too, right? I think there are probably reasonable arguments to be made for varying approaches.
Perhaps at the end what we’re going to come back to is to have an approach that is agreed to for one’s institution for the categories of patients, rather than depending on the need to decide what to do at the time for each patient. For example, a relatively low-risk patient going straight to the catheterization lab, or even a patient, let’s say, with ST elevation in lead aVR and diffuse ST depression where one might be more concerned about the need to go to coronary artery bypass graft, is it reasonable to hold off on acute P2Y12 administration? If the patient is going to the catheterization lab within an hour or two, is it OK to just wait until the angiography is performed? This is another important question.
Tim, let’s get back to the issue of first treatment and how to address choosing antithrombotic therapy at first presentation. In Minneapolis, you got a standard protocol to every one of your referring hospitals for STEMI, and this established a standardized approach in your system for use of antithrombotic therapy.
DR. HENRY: No question. Let me comment on several things that we’ve talked about so far! The P2Y12 inhibitor can be given by the paramedics. We had several pilot trials where we did it very successfully and we were able to decrease treatment time by probably 30 minutes. Peter was correct that the pretreatment data are conflicting. I think, certainly from a pharmacodynamic point, the earlier you get the P2Y12 inhibitor on board, the better.
The completed trials all have nuances. I still think overall evidence supports having the P2Y12 inhibitor on as soon as possible, but being able to do it accurately is important. The only risk is an increase in bleeding if you have to go to surgery. For STEMI, from my perspective this is an extremely uncommon problem, less than 2% for sure. In non-STEMI it is less rare, more like 8% to 12%. You need to consider those things in your standard protocol.
What I would like to do, Chris, is jump back even more generally and consider this whole concept of institutional protocols. I think it is critical that every institution actually takes the time to do this. For ACS we had what we called Level One, which was STEMI. We had Level Two, which was non-STEMI, including urgent Level Two, for patients who had ongoing chest pain, or had dynamic ECG changes, rising enzymes, or heart failure or arrhythmia. In other words, a non-STEMI patient that was high-risk. We had a plan for that patient, and a standardized protocol for non-emergent STEMI. Level Three was unstable angina, and Level Four included patients with non-cardiac chest pain (Figure).
When they presented in the emergency room, we had a standardized approach to all those patients so that everybody knew the plan and it was done very efficiently. That protocol needs to include the pre hospital component, the ED component, the catheterization lab or diagnostic component all the way through discharge and, in my perspective, even after discharge. For example which STEMI patient needs a follow-up echocardiogram? When do you obtain follow-up lipid labs? The more you can standardize the process from prehospital to 1 year post-discharge, the better the outcomes you’re going to get for your system.
For each of these areas, it requires a small group of interested parties—interventional cardiologists, non-interventional cardiologists, administrative, nursing, ED representatives—depending on the problem you’re trying to solve. Get them in a room and empower them to design a protocol. Then, implement the protocol in your institution and, just as important as implementing it, keep track of how it works.
Some protocols will be perfect from the beginning. Great! Some won’t be and will need revisions. When you put a protocol in place, you’ll quickly see what works or what doesn’t work, and then you’ll be able to adapt that protocol. Also, as we gain new medical knowledge, we are able to utilize new medical knowledge to adapt the protocol.
I’ve seen the absolute benefits of having these protocols in place to decrease variability, and to improve outcome. I really want to emphasize, it is not just in the prehospital or in the ED phase, it is all the way through discharge. Those things make a big difference.
We’re talking about ACS today, so certainly that includes STEMI, non-STEMI, unstable angina, out-of-hospital cardiac arrest, but I really do believe that this concept applies to all acute cardiovascular emergencies. We should have the exact same approach—in fact, we did—for aortic dissection, for abdominal aortic aneurysm, for critical ischemia, for pulmonary embolism, and for stroke. The better that we’re able to standardized care, the better the outcomes we’re going to have.
DR. GRANGER: Thanks, that is a great summary, Tim. I’m going to make the presumption that, because you said it so clearly and so well, we all agree that one of our strong recommendations from this particular discussion is going to be that every institution should have a protocol for the basic framework of applying these treatments for ACS.
DR. BERGER: Chris, I do agree with that, and let me just mention two thoughts that Tim’s comments triggered. One is he talked about a perhaps 2% frequency of need for bypass, which is one of the bad things that can happen after you’ve given P2Y12 inhibitor to a patient. Not only do I agree that it is very, very rare—rarer than ever—but also I think that a lot of patients who are taken to surgery very shortly after presenting with a STEMI would benefit if the surgery were delayed a little bit. When surgical disease—multivessel disease or left main disease—is found on a catheterization for STEMI, I nonetheless think it is almost always appropriate to still treat the infarct vessel, abort the infarct, and then, when the patient is less critically unstable, take care of left main or multivessel disease if indeed it is not percutaneously revascularizable.
The other thing I want to say relevant to pretreatment with a P2Y12 inhibitor in STEMI is that radial procedures are performed in the overall majority of STEMIs at the place I last practiced, Geisinger, and in many of our hospitals where I now practice at Northwell. That reduces the potential downside of giving a potent P2Y12 inhibitor upstream.
DR. GRANGER: That is an important point, I think, and it addresses another one of these transition clinical interfaces of going from the ED to the catheterization lab. Deb, from an ED perspective, comment further on the whole issue of risk stratification. You mentioned a couple of tools—the HEART score, TIMI risk score—and we have the Global Registry of Acute Coronary Events (GRACE) risk score,4,5 for which we have some evidence might be useful to guide who would get particular benefit from an earlier catheterization strategy.
And then we have simple things like, I think Tim mentioned, are there elevated cardiac biomarkers at presentation? Dynamic ST changes? Heart failure? Could you speak a little bit more to what is helpful to you as an emergency physician for risk stratification?
DR. DIERCKS: I think the biggest challenge we have are management of those without a classic presentation. I fully agree, for the patient with typical symptoms, elevated markers, and an abnormal ECG, everyone tends to agree with the management strategy. In those patients without such a clear management path are where algorithms, protocols, and order sets are invaluable to get everyone the right medications as soon as they need them. Where the risk stratification tools become very helpful are with those with more atypical symptoms, who have low elevation in their initial troponin, and then you’re stuck asking, “Alright, is the next one going to be higher or should I just wait? Is this really secondary to some other cause?” That is where the risk stratification tools are useful.
I think emergency physicians are much more comfortable using risk stratification tools to rule out a disease and to identify low risk. In these situations, the way we are really using them is to identify those at higher risk for adverse events. The TIMI score has been used for that, with high-risk being scores over four. The GRACE score, because it is so complex—although I think it has probably got the best data—hasn’t gotten used as much in the ED setting.
DR. GRANGER: Deb, we should probably at least mention the fourth-generation troponins that we anticipate may be available in the United States in the next several months. You may have more updates on that, and that will also be quite valuable in a more rapid ability to identify at least the very low-risk patients.
DR. DIERCKS: Exactly. I think that we’re going to be transitioning to more a rapid decision, including discharge to those low-risk patients, and probably changing how we use our observation units a lot for these patients with chest pain.
DR. GRANGER: Actually, Deb, comment on this, because I think this may be another key opportunity for us around this topic of institutional protocols. When we get the ultrahigh sensitivity troponin, if there isn’t a protocol in place, it is going to be a disaster for cardiology and for emergency medicine, I think, not knowing what to do with detectable troponins. And if one uses, for example, the Abbott troponin-I assay, something like 80% of normal people will have a detectable level. We really will be forced to have more guidance around what to do with these, and that might be an opportunity to make sure institutions have their ACS algorithms up to date.
DR. DIERCKS: I’ve been going through that process in developing a pathway at UT Southwestern. It is interesting the barriers that come up from an emergency medicine perspective, and that is fear of discharging someone inappropriately, and having the institution not support them if something happens. That is really where these multidisciplinary pathways and institutional protocols really help the emergency physician.
We have developed an institutional pathway, and that provides some reassurance that if you’re going to disposition somebody and they’re that less than 1% that come back with something different than expected, that you’ll have some institutional support for your decision making. It has been interesting really getting down to the bottom of what the barriers are to protocol development, and it really is physician fear of critique if something goes wrong.