Heart "alarm": three detailed interpretations of myocardial infarction

Acute coronary syndrome (ACS) is a severe acute condition in coronary heart disease, which originates from the rupture or erosion of coronary atherosclerotic plaques, followed by complete or incomplete occlusive thrombosis. This pathological process leads to a series of clinical syndromes, including acute ST-segment elevation myocardial infarction, acute non-ST-segment elevation myocardial infarction, and unstable angina (UA). As a common and serious cardiovascular disease, ACS has high morbidity and mortality.

In the diagnosis and prognosis of ACS, cardiac markers - the three myocardial infarctions play a vital role. Given the rapid onset and serious harm of ACS, it is crucial for ACS patients to select highly specific early markers to achieve early diagnosis and timely treatment.

The accurate detection of CK-MB, myoglobin and cardiac troponin in the three myocardial infarction indicators has a profound impact on the timely treatment and prognosis of patients. The following is a detailed description of these three indicators:

1. CK-MB (creatine kinase isoenzyme):

Normal range: When using electrophoresis, the normal value of CK-MB is usually less than 0.05 (i.e. CK-MB is less than 5%). If the enzyme rate method (at 37°C) is used for testing, the normal range of CK-MB is 0 to 18 U/L.

Clinical significance: CK-MB is an isoenzyme of creatine kinase, which is mainly present in myocardial cells. When myocardial cells are damaged, such as acute myocardial infarction, the level of CK-MB will increase. In addition, hypothyroidism, cerebrovascular disease, lung disease, chronic alcohol poisoning, muscle cramps during postoperative recovery, after cardiac resuscitation, shock, tetanus, and skeletal muscle injury may also lead to elevated CK-MB.

Note: Before testing CK-MB, you should avoid smoking, drinking, and reduce the intake of high-cholesterol foods. Blood should be drawn on an empty stomach during the test, and strenuous exercise should be avoided before blood drawing. After blood drawing, press the needle hole for 3-5 minutes to stop bleeding, and avoid massaging to prevent the formation of subcutaneous hematoma.

2. Myoglobin (Myo):

Normal range: 29-75 ng/mL for men and 26-58 ng/mL for women.

Clinical significance: Myoglobin is a protein present in muscle cells whose main function is to store and transport oxygen. In the case of myocardial infarction, myoglobin levels rise rapidly and are usually detectable within 1-2 hours after the onset of symptoms. Therefore, myoglobin is an important indicator of acute myocardial infarction. However, it may also be affected in other diseases or conditions, such as muscle damage, extreme exercise, chronic kidney disease, anemia or severe hypoxia.

3. Cardiac troponin (CTnI/CTnT):

Normal value range: usually less than 0.1ug/L.

Clinical significance: Cardiac troponin is a specific marker of myocardial necrosis and has a high specificity for the diagnosis of myocardial infarction. When myocardial cells are damaged, cardiac troponin is released from the cells, causing its level in the blood to increase. An increase in cardiac troponin usually means the presence of myocardial necrosis, which is common in acute myocardial infarction. In addition, heart diseases such as myocarditis and heart failure may also lead to an increase in cardiac troponin.

In general, CK-MB, myoglobin and cardiac troponin in the three myocardial infarction items are important indicators for assessing the degree of myocardial damage. When interpreting these indicators, it is necessary to comprehensively consider their values ​​as well as the patient's clinical manifestations and other examination results to reach an accurate diagnosis.

Three interpretations of myocardial infarction:

Look carefully at the three indicators of myocardial infarction and remember their meaning.

Be careful if CK-MB is high, as it may cause myocardial damage.

Myoglobin increases several times, and muscle damage is difficult to avoid.

Cardiac troponin is the most specific and is used to diagnose myocardial infarction.

If you find any abnormalities, don't panic; the doctor's interpretation will be more accurate.

Start protecting your heart early and live a healthy and peaceful life.

(Author: Liu Fei, Medical Laboratory Department, Hechuan District People's Hospital, Chongqing)