Increased troponin level indicates myocardial infarction

Troponin is a common examination item. When troponin is greater than 0.5, it can basically be judged as myocardial infarction. The diagnosis can be confirmed through electrocardiogram and the patient's chest pain symptoms. After suffering from myocardial infarction, you should go to the hospital for treatment in time. You must stay in bed and rest at ordinary times. In addition, during the diagnosis, you must also understand what type of myocardial infarction it is, and then carry out symptomatic treatment.

How to identify myocardial infarction

Back to the actual problem, if we find that troponin is elevated in patients with combined renal failure, severe infection, and heart failure, how should we make a differential diagnosis? Let me talk about some of my personal experiences.

1. The current “1+1” model for diagnosing myocardial infarction may be inappropriate

To diagnose myocardial infarction, we must first understand the diagnostic criteria for myocardial infarction. Currently, the most commonly used diagnostic criteria for myocardial infarction come from the "Global Definition of Myocardial Infarction" jointly developed by ESC, ACCF, AHA and WHF, also known as the "1+1" model. The first "1" refers to an increase in myocardial biochemical markers, which is higher than the reference upper limit of 99%; the second "1" refers to one piece of evidence of myocardial ischemia, including symptoms, electrocardiogram, and imaging, as follows:

Symptoms: Symptoms of myocardial ischemia

ECG: New ST segment changes, new LBBB, one of the new pathological Q waves

Imaging: (UCG, radionuclide, MRI, CTA) confirms new loss of vital myocardium or new regional wall motion abnormalities

Under normal circumstances, there is no problem in diagnosing myocardial infarction using the "1+1" model. However, in patients with renal failure, severe infection, and heart failure, the proportion of non-specific elevations of troponin (exceeding the upper limit of 99%) is very high, and it is inappropriate to still use it as one of the main diagnostic criteria.

2. Possible reasonable diagnostic methods

For patients with renal failure, severe infection, and heart failure, a large proportion of patients have nonspecific elevations of troponin, and there are two possible reasonable diagnostic models. The following content contains a lot of personal opinions, please treat it with discretion:

(1) Use the classic myocardial infarction diagnosis model

Before the "1+1" model, the diagnosis of myocardial infarction used the classic "3 out of 2" model:

(1) Symptoms of ischemic chest pain; (2) Typical dynamic changes in electrocardiograms; (3) Dynamic changes in elevated myocardial enzymes

If 2 of the 3 conditions are met, myocardial infarction can be diagnosed.

Therefore, patients with combined renal failure, severe infection, and heart failure should be carefully asked whether they have symptoms of ischemic chest tightness or pain, and their electrocardiograms should be reviewed dynamically. If both symptoms and ECG changes are present, myocardial infarction can be diagnosed regardless of the enzyme results. Of course, imaging findings of new loss of vital myocardium or new regional wall motion abnormalities are also helpful for diagnosis.