Sinus rhythm is a sinus heartbeat rhythm, and ECG st-t changes generally represent the presence of myocardial ischemia manifestations. Sinus rhythm is the rhythm of the heart beat that is conducted from the sinus node and is normal. If the heart does not conduct impulses from the sinus node, it is said to be an ectopic rhythm and is abnormal. The st-t changes on the electrocardiogram usually refer to elevation or depression of the st segment and flattening or inversion of the t wave. Elevation of the st segment arching back upward often represents an acute myocardial infarction, which requires a definitive diagnosis and urgent management as soon as possible. Other diseases such as ventricular wall tumor and acute pericarditis can also present with elevated st segments. A downward shift of the st segment usually indicates the presence of myocardial ischemia, coronary artery disease, angina pectoris, etc. Hypoplasia or inversion of the t wave is also a sign of myocardial ischemia. If the electrocardiogram shows sinus rhythm st-t changes, it can indicate that the origin of the heart beat is normal, but the existence of myocardial ischemia, usually further examination, such as cardiac enzymes, dynamic electrocardiogram, cardiac ultrasound, etc., in order to clarify the cause of the disease, and then develop the next step of the treatment plan. It is recommended to consult the doctor as soon as possible to avoid delaying the condition.