What is the most common cause of ST segment depression?

The most common cause of ST segment depression is myocardial ischemia. This occurs when there is an inadequate supply of oxygenated blood to the heart muscle, often due to coronary artery disease or other factors that compromise blood flow. During periods of ischemia, the electrical activity of the heart can be altered, leading to characteristic changes on an electrocardiogram (ECG), including ST segment depression.

ST segment depression reflects the subendocardial ischemia that can happen during exertion or increased heart rates when the demand for oxygen exceeds the supply. It is important to recognize this change as it can indicate angina or even an impending myocardial infarction. Understanding the connection between myocardial ischemia and ST segment changes helps in the timely identification and management of patients at risk for severe cardiac events.