An ST depression is a possible outcome of an electrocardiogram (ECG) test. It can indicate health conditions like hypokalemia, myocardial ischemia, or a side effect of medications.

If a doctor suspects there may be something wrong with a person’s heart, they may decide to order an ECG. This is a test that measures the electrical activity in a person’s heart. This test can help a doctor diagnose a large number of conditions, including:

This article explains what an ST depression is and what may cause it. It also outlines some possible treatments for specific causes of ST depressions.

A doctor reading the results of an ECG test to check for ST depression.Share on Pinterest
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ST depression is a term that refers to the position of the ST segment in a person’s ECG results.

ECG results appear in a graph of spikes and valleys. The points on this graph represent different waves of electrical activity. There are three waves that make up this graph.

These three waves are:

  • P wave: This wave shows the electrical activity running through the heart to the atria. These are the two upper chambers of the heart.
  • QRS complex: This shows the electrical activity running through the heart to the ventricles. These are the two lower chambers of the heart.
  • T wave: This shows the electrical activity involved in the heart’s ventricular repolarization. This means it shows the electrical reset of the heart as it prepares for the next cardiac cycle.

The ST segment appears in the ECG results. It corresponds to the area visible at the end of the QRS complex and the beginning of the T wave.

A 2021 article notes that if the ST segment appears abnormally low and sits below the baseline, then a person is said to have ST depression. ST depression has associations with a number of medical conditions, so it can have a variety of causes.

Clinically speaking, the ST segment represents the period in the cardiac cycle when the muscular layer of the heart maintains contraction to expel blood from the ventricles.

There are a number of things that can cause a person to have ST depression in their ECG results.

The conditions that have associations with ST depression include:

  • Myocardial ischemia: This is the term for an imbalance of oxygen supply to the heart. It often occurs when something obstructs the blood flow to the heart muscle. This may be due to a partial or complete blockage of a coronary artery and can lead to a heart attack.
  • Hypokalemia: This is a condition that occurs when a person’s body excretes too much potassium. Hypokalemia can cause a person to not have enough potassium in their blood. Low levels of potassium can cause a number of symptoms, including muscle weakness that can result in paralysis.
  • Left bundle branch block: This is a condition where the electrical impulses to the heart’s left ventricle become slower. This can make it more difficult for the heart to pump blood efficiently.

ST depression is also associated with the use of the medication called digitalis. A person may use digitalis to treat certain heart conditions, such as heart failure and arrhythmia.

A person can treat the condition that is causing their ST depression. Below are some treatment options for some conditions that can cause ST depression.

Treating hypokalemia

Hypokalemia is a symptom of another disorder rather than a disease in itself. To improve a person’s potassium levels, a doctor will treat the underlying condition causing the hypokalemia.

They may also advise a person to include more potassium in their diet or take potassium supplements.

In severe cases, a doctor may administer potassium chloride orally or intravenously.

Treating myocardial ischemia

The most effective treatment for myocardial ischemia is the use of beta-blockers. These medications relieve stress on the heart by slowing down a person’s heartbeat. They do this by blocking the action of certain hormones in the nervous system.

Beta-blockers can reduce the number and the duration of ischemic episodes in people with myocardial ischemia.

A person may also take:

Another treatment option for people with myocardial ischemia is psychotherapy. Stress can increase a person’s risk of developing myocardial ischemia and psychotherapy can work to reduce this stress.

Psychotherapy aims to help a person understand their feelings. By talking with a therapist, a person can equip themself to face new challenges and tackle feelings of stress and anxiety.

Treating a left bundle branch block

There is no specific treatment for a left bundle branch block. A doctor may wish to treat any underlying causes that a person may have.

The American Heart Association states that, despite there being no specific treatment, a person with left bundle branch block should have regular checkups with a doctor. This is so they can monitor the person’s condition and ensure that no other changes occur.

If a person has an ST depression, their outlook will depend on what is causing that specific ECG result.

If a person has hypokalemia that is causing their ST depression, it may be the result of one of many conditions. Some conditions that lead to hypokalemia are simple to resolve and others may be more complex.

If a person has myocardial ischemia, then they may treat the condition with beta-blockers. If they receive an early diagnosis and treat their condition early they can improve their outlook.

A person may also reduce their risk of dangerous complications such as heart disease, stroke, and heart attacks in a number of ways. These include:

  • eating a healthy balanced diet and avoiding foods that are high in saturated fats
  • maintaining a healthful weight
  • getting regular physical exercise
  • avoiding smoking

An ECG is a test that medical professionals use to analyze the electrical impulses in a person’s heart.

An ST depression is a specific outcome that may appear in a person’s ECG results. It occurs when the ST segment appears abnormally low and sits below the baseline in a person’s results.

An ST depression can occur due to medical conditions including hypokalemia, myocardial ischemia, and a left bundle branch block. The use of the medication digitalis can also cause this specific ECG result.

A person may treat the underlying condition that is causing their ST depression.

A person with an ST depression may also wish to make some lifestyle changes to help improve their heart health. This can include eating a healthy diet, getting regular physical exercise, avoiding smoking, and maintaining a moderate weight.