What Does ST Segment Elevation Mean?

What does ST segment elevation mean? ST segment elevation is a manifestation on an electrocardiogram (ECG). Its diagnosis requires a comprehensive evaluation of the patient's condition, including symptoms, ECG changes, ultrasound examination, and myocardial enzyme status. Patients with ST segment elevation may experience chest pain, which is often a precursor of acute myocardial ischemia, myocardial infarction, or myocarditis. Persistent ST segment elevation may also indicate ventricular aneurysm.

ST segment elevation refers to the elevation of the ST segment above the isopotential line (or the PR segment). Diagnostic criteria include an ST segment elevation ≥0.1mV at 0.06-0.08S after the J point in limb leads, ≥0.25mV in right chest leads, and >0.10mV in left chest leads, considered abnormal. It is important to note the degree, morphology, duration, and relationship with symptoms of ST segment elevation. Acute chest pain accompanied by rapid ST segment elevation may indicate coronary artery obstruction or myocardial damage caused by other etiologies. Injury-type ST segment elevation reflects transmural myocardial ischemia. Patients often present with persistent severe chest pain and other clinical manifestations and signs of myocardial ischemia, such as elevated troponin levels, seen in the hyperacute phase of myocardial infarction and acute myocardial infarction.

1. Superacute or acute myocardial infarction: Patients may present with significant symptoms such as chest pain, sweating, and syncope. ST segment elevation may be seen in a slanted or concave-upward pattern, accompanied by widening and tallening of the T wave, which gradually becomes low, biphasic, or inverted. Arrhythmias are common.

2. Variant angina pectoris: Immediate ST segment elevation of more than 0.20mV and tall, pointed T waves may be observed during chest pain attacks, often accompanied by various ventricular arrhythmias.

3. Ventricular aneurysm: Persistent ST segment elevation in a concave-upward or upwardly slanted pattern may be observed long after acute myocardial infarction. If ST segment elevation persists after one month of acute myocardial infarction, ventricular aneurysm should be highly suspected, and further confirmation can be obtained through echocardiography.

4. Acute pericarditis: Universal ST segment elevation is observed except in aVR and V1 leads, without necrotic Q waves. T waves may be low or inverted. In cases of large pericardial effusion, ORS amplitude may decrease or show low voltage. In constrictive pericarditis, the electrocardiogram remains unchanged in both supine and upright positions.

5. Acute myocarditis: Severe cases may present with ST segment elevation, and some patients may have abnormal Q waves, resembling acute myocardial infarction. As the condition improves, the ST segment gradually improves and returns to normal, and the abnormal Q waves disappear.

6. Myocardial injury after cardiac surgery: Transient injury-type ST segment elevation may occur after cardiac surgeries such as bypass surgery, coronary intervention, radiofrequency ablation, and mediastinal tumor resection, typically lasting for about a week.

7. Left bundle branch block: Leads Ⅰ, aVL, V5, and V6 may show R-wave patterns or blunt R waves. Leads V1 to V3 may show QS patterns or rS patterns with significant upwardly slanted ST segment elevation.

8. Left ventricular hypertrophy: ST segment elevation may be evident in leads V1 to V3, positively correlated with the depth of the S wave. Simultaneously, there may be manifestations of left ventricular hypervoltage and ST segment depression in leads V4 to V6, which can be further confirmed through echocardiography.

9. Hypertrophic cardiomyopathy: Leads dominated by S waves may show upwardly slanted or concave-upward ST segment elevation (particularly evident in leads V1 to V3).