Once you learn to read an EKG initially, the most important thing to keep in mind is not to look at the graphs just once. Be sure to pay attention to how they change, especially over a short period of time when the condition is more severe. So when a doctor is reviewing an EKG for a patient the more he or she should have the better, plus EKGs aren’t expensive and are very helpful in making a definitive diagnosis as quickly as possible. The following are some common examples of ECG changes in diagnosing diseases 1. ST segment is elevated or depressed at the onset of the disease, and then returns to normal or close to normal soon after the onset of the disease or gradually. 2. 2. When the ST segment is elevated at the onset of angina pectoris and returns to normal immediately after the onset of the attack, it is most commonly seen in angina pectoris of a variable nature (caused by coronary artery spasm). 3.When the ST segment is gradually elevated one at a time with severe pain in the precordial area, it gradually decreases after a few days, and may be lowered to the normal position or close to normal when the condition is cured, which is often seen in acute myocardial infarction. 4, ST segment depression at the onset of angina pectoris, and recover immediately after the angina pectoris improves, most often seen in stable or unstable angina pectoris. 5, ST segment depression lasts for a long time, slow recovery, may also be seen in non-ST segment elevation myocardial infarction. For those who have slow changes and heavy pain, blood should be drawn for myocardial biochemical markers such as myocardial enzymes and troponin, and if there is a significant increase, it will be conducive to the diagnosis of myocardial infarction.