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Show Notes

An elevated high-sensitivity troponin indicates myocardial injury, but does not always mean myocardial infarction (MI).
Always interpret troponin in the clinical context history, ECG, imaging, and serial troponin measurements all matter.

🔹Step 1: Look at the Trend

A rising or falling (delta) troponin is more concerning than a single elevated value.
Serial troponins (typically 2–4 hours apart) help distinguish acute from chronic injury.

🔹Step 2: Consider Other Causes

Chronic kidney disease can cause persistently elevated troponin due to reduced renal clearance.
Troponin elevation alone should not automatically trigger an MI diagnosis.

🔹Step 3: Assess for Ischemia

Look for:

  • Typical ischemic chest pain
  • Dynamic ECG changes
  • New wall-motion abnormalities on echocardiography

Type 1 vs Type 2 MI

🔹Type 1 MI: Acute plaque rupture causing coronary artery occlusion.

🔹Type 2 MI: Oxygen supply-demand mismatch (e.g., sepsis, hypoxia, tachyarrhythmia).

Acute Coronary Syndromes

🔹STEMI: ST-segment elevation + acute myocardial infarction.

🔹NSTEMI: Troponin elevation without ST elevation.

🔹Unstable Angina: Ischemic symptoms without troponin elevation.

Risk Stratification

TIMI and GRACE scores help estimate risk in NSTEMI.
Clinical judgment remains the most important factor when deciding on invasive management.

Clinical Pearls

  • Elevated troponin ≠ Heart attack.
  • Always trend troponins.
  • Diagnose MI only when myocardial injury is accompanied by evidence of ischemia.
  • Treat the patient, not just the lab value.

Transcript

If you’ve ever been puzzled by troponin levels, myocardial injury, or myocardial infarction, fear not. Today, we’ll take a brief moment to review these important concepts. Before we dive in, for clarity, when we say troponin, we’re referring to high sensitivity troponin. The first thing is that the troponin value is only one piece of the clinical picture. Yes, an abnormal troponin value indicates a myocardia injury, but a troponin elevation does not always equal myocardial infarction.  
 
So how do you know if a troponin elevation indicates a myocardial infarction? When we check troponin, we usually trend troponin because it’s the trend that matters more so than an isolated troponin elevation. It’s really the relative change or delta that can clue us in to a true myocardial infarction. For example, if you repeat a troponin 2 hours after an initial abnormal value and it’s doubled, that might be more concerning for a developing myocardial infarction versus the repeat value only being a little bit higher.
 
So, what do you do if you have a patient coming in with an acute change in their serum troponin over a time interval of 2 to 4 hours? You assess for evidence of clinical signs and symptoms of ischemia. Chest pain radiating to the left arm or shoulder has the highest likelihood ratio for acute MI in terms of symptoms.
 
Additionally, ask your patients for any symptoms on exertion since that might be from limited blood flow to the coronary arteries. And of course, patients don’t always follow the textbook. Some presentations include very non-specific symptoms such as shortness of breath, nausea, or a burning sensation. So, what do we want to look for on the EKG? Look for EKG changes from prior and dynamic changes on repeat EKGs. For example, are the T-wave inversions or ST depressions changing? Also on TTE, you can look for focal wall motion abnormalities indicating the area that might have an acute ischemic process.
 
The next question then is whether an acute myocardial infarction is due to a plaque rupture within a coronary artery. If so, we say the patient has a type 1 myocardial infarction. On the other hand, if it’s a supply demand mismatch problem from some underlying process such as sepsis, that rise in troponin will fall under type 2 myocardial infarction. Let’s take a moment to go over the different acute coronary syndromes which describe a myocardial infarction due to an acute plaque rupture. In particular, let’s talk about STEMI, NSTEMI, and unstable angina.
 
In patients who come in with an acute troponin elevation on serial lab checks concerning chest pain and ST elevations in two contiguous leads, we classify this as ST elevation MI. In contrast, patients with troponin elevation, chest pain, but without ST segment elevation are usually designated as non-ST segment elevation MI or an NSTEMI. An important point here is that the type 1 and type 2 designations I mentioned before are most often used when talking about NSTEMI. When it comes to NSTEMI, there are two main tools used to evaluate a patient’s risk for major adverse cardiac events. The TIMI, which is most historically validated, and the Gray score, which accounts for the physical exam and markers of perfusion. It’s most useful in patients with heart failure or shock. These can help guide management decisions. For example, high-risk patients are taken to the cath lab sooner than low-risk patients.
 
Lastly, unstable angina refers to patients in which we don’t see ST elevation or troponin elevation, but the pathophysiology behind the chest pain is presumed to be a result of a plaque rupture. These cases are important reminders that our decision making relies on clinical judgment. Ultimately, the decision to take a patient to the lab doesn’t require a risk calculator. Clinical judgment cannot identify “low-risk” patients who are having clear symptoms of an occluded coronary artery. Even when patients have no troponin elevation, a convincing story with ongoing chest pain often leads to catheterization. At the end of the day, clinical suspicion is more important than any risk factor.
 
So, let’s tackle two learning cases. Say you have a 65-year-old man who comes into the ED with crushing subternal chest tightness lasting for 2 hours. His initial troponin is 70 and a repeat 2 hours later is 150. His EKG shows new ST depressions. What’s the most likely diagnosis? If you guessed myocardial infarction, most likely of the type 1 variety, you’re correct.
 
Okay, now let’s try something a bit harder. We have a 55-year-old man coming in with shortness of breath and a cough. He has a history of severe COPD and is diagnosed with an exacerbation. His initial troponin is 45 and a repeat 2 hours later is 60. His EKG shows no ischemic changes and he denies chest pain. What’s the most accurate classification of his troponin elevation?
 
Here we’re dealing with an acute moardial injury likely in the setting of an acute illness, but we would not say this patient has a myocardial infarction. That’s why it’s important to consider the overall clinical presentation when interpreting troponin.
 
A good question when interpreting troponin values is if there’s a reason why the troponin may not be clear from the body and as a result falsely elevated. A key point is that 90% of troponin are cleared by the kidneys and 10% by the liver. So in patients with poorly functioning kidneys, reduced renal clearance leads to elevated values. Here there’s often no need for further workup specifically for that troponin elevation. Though having any elevated troponin in a patient with renal disease does carry prognostic implications.
 
I hope our talk today has helped. For more information, check out these two Core IM podcasts. The mind the gap episode on acute coronary syndromes and the five pearls on troponin episode. You can find them on Apple podcast, Spotify, and YouTube. See you next time.

Full Podcast

5 Pearls on Troponins

Acute Coronary Syndrome (ACS) and the TIMI Risk Score