This is part one of my three-part series on elevated troponin in the ICU. To start with, here’s a relatively common ICU scenario:
You are admitting a critically ill patient to the ICU. Let’s say it was sepsis. The patient received a comprehensive ER workup. A troponin level was added to the initial lab workup, and it comes back elevated. Now the medical team has questions for you.
- Does the patient have NSTEMI?
- Are we starting heparin / aspirin / clopidogrel?
- Should we recheck troponin? If so, at what interval, and for how long?
- Are we consulting cardiology for elevated troponin?
My personal approach here is to think about troponin the same way I would think about any lab result that may go out of range as a result of a physiologic process (high or low pH, lactic acid, CRP, ESR, procalcitonin, ferritin, WBC, albumin, etc). Just like these other examples, troponin elevation could have many explanations.
So if we think back to the ICU scenario, before you can answer any of those four questions, I would suggest that you think about the differential for elevated troponin in general, and then think through your present case to see if you have an acceptable explanation for your patient’s troponin level.
Cardiologists who I trained under taught me to think of troponin elevation in two categories: cardiac and non-cardiac. That is to say, is the primary problem leading to troponin elevation related to the heart itself, or something systemic / outside of the heart. Fortunately, we don’t have to re-invent the wheel here, this work has already been done for us:
Here’s another table from the ESC’s (European Society of Cardiology) European Heart Journal in 2011 titled “Troponin elevation in coronary vs. non-coronary disease.”
When I was a medical student, I had one precious folded up piece of paper where I wrote down information that felt important to me. I ended up keeping it through most of my residency until it finally fell apart. One section of that paper was dedicated to my two troponin elevation lists: cardiac and non-cardiac. I would challenge you to do something similar and in every case you have with troponin elevation, see if you can explain it using the list you have.
Of course, there will be many true cases of myocardial infarction and ACS. Keep a high suspicion, especially with very elevated troponin levels. But as a public service message from cardiologists, please resist the temptation to label every troponin as NSTEMI.
- Think of troponin as a lab result that can elevate from multiple causes, not just myocardial infarction
- It’s helpful to keep a list of reasons for elevated troponin
In part 2 of this series, we will go into the definition of myocardial infarction and how to make it work for you to reduce your decision-making burden in evaluating cases of troponin elevation. Stay tuned! And as always, we love your feedback. Please leave a comment and let Team Vitals know what you think.