A Stress Echocardiogram (a.k.a. stress echo) is a diagnostic test that measures the activity of the heart during physical stress. The purpose of a stress echo is to evaluate how well the heart responds to increased demands for blood and oxygen when the body is under stress, typically induced by exercise.

Here is the sequence of events with a stress echocardiogram:

• The patient arrives wearing comfortable clothing and athletic shoes.
• An ECG is recorded and ultrasound images of the heart are captured to record baseline readings of the patient’s heart at rest.
• The patient gets on a treadmill that is gradually elevated in order to increase the patient’s heart rate.
• Once the patient struggles, the patient steps off of the treadmill and immediately gets their ECG recorded and ultrasound images of the patient’s heart at stress are captured.
• The cardiologist analyzes the results and provides guidance to the patient on suggested course of action.

There are numerous metrics recorded with a stress echocardiogram, too many to discuss here. However, there are two metrics that are relevant for discussion here:

• Ejection Fraction (EF) – a measure of the percentage of blood pumped out of the heart with each contraction.
• Horizontal ST Depression – a value of > 0.5 mm indicates possible myocardial ischemia, which is when blood flow is obstructed by blockage of some degree in a coronary artery. 

The following table summarizes the different degrees of EF:

Some of the key implications of a severely reduced ejection fraction include:

1. Heart Failure: A severely reduced ejection fraction is often associated with heart failure. Heart failure occurs when the heart is unable to pump blood effectively to meet the body’s needs. It can lead to symptoms such as shortness of breath, fatigue, fluid retention (edema), and exercise intolerance.
2. Increased Mortality Risk: A low ejection fraction is a strong predictor of adverse cardiovascular events and mortality. Individuals with severely reduced ejection fraction have a higher risk of sudden cardiac death and other complications.
3. Impaired Exercise Capacity: Reduced ejection fraction can result in decreased cardiac output, limiting the ability of the heart to supply oxygen-rich blood to the body during physical activity. This can lead to exercise intolerance and reduced quality of life.
4. Arrhythmias: Severe reductions in ejection fraction can disrupt the normal electrical activity of the heart, increasing the risk of arrhythmias (irregular heart rhythms). This can further contribute to the risk of sudden cardiac death.
5. Complications of Heart Failure: Chronic heart failure can lead to complications such as kidney dysfunction, liver congestion, and pulmonary edema. It can also exacerbate other health conditions.
6. Impaired Pumping Function: The heart’s pumping function is compromised when the ejection fraction is severely reduced, affecting the ability of the heart to efficiently circulate blood and maintain adequate perfusion to vital organs.