A cardiac stress test, also called the exercise stress test, evaluates the working condition of the heart. Approximately 18 million people over 20 are diagnosed with coronary artery disease annually. These numbers can be reduced if the symptoms are diagnosed in the early stages using diagnostic tests like stress tests. The following article lists the types of cardiac stress tests, their procedures, and why they are important, among other factors.

What can a cardiac stress test help diagnose?
There are various reasons why a general practitioner or heart specialist might suggest a cardiac stress test. Here are some of them below:

• Arrythmia
  Heart rhythm problems or arrhythmia occur due to poor coordination of electrical signals that are responsible for a rhythmic heartbeat. The poor coordination can cause a heart to beat too slow, too fast, or irregularly.
• Coronary heart disease
  The coronary artery is one of the major blood vessels supplying the heart with blood, oxygen, and other nutrients. A buildup of deposits, such as plaque or other underlying conditions, can damage this artery, leading to symptoms like discomfort and shortness of breath.
• Congenital heart disease
  A person with CHD or congenital heart disease is said to have a defect in their heart, such as a hole or impaired blood vessels.
• Hypertrophic cardiomyopathy
  HCM or hypertrophic cardiomyopathy is a heart condition that causes abnormal thickening of heart muscles. It can make it difficult for the organ to pump blood.

For patients already diagnosed with heart disease, this test can be used as:

• Guide treatment
  A cardiac stress test can help determine the best possible treatment option if a patient is already diagnosed with a heart condition.
• Post-surgery procedure
  Doctors may use this procedure to determine whether it is safe to perform a heart surgery such as valve replacement or transplant.

How does a cardiac stress test work?
A cardiac stress test requires the patient to walk on a treadmill or ride a stationary bicycle, making the heart pump blood faster. The test assesses the response to the increased exertion by measuring parameters like blood pressure, heart rate, oxygen levels, and the electrical activity of the heart. It compares the result with standard data based on age and gender.

What are the types of cardiac stress tests?
The following type of cardiac stress tests help evaluate various parameters like heart rate, blood pressure, electrical activity, and oxygen levels, among others.

• Exercise stress echocardiogram
  An exercise stress echocardiogram is a type of a basic cardiac stress test that provides additional parameters like evaluating the efficiency of the blood flow through the heart chambers and valve functions. It does so by using sound waves like an electrocardiogram.
• Cardiac rehabilitation stress test
  A cardiac rehabilitation stress test is done to help people with heart disease be more physically active. It also helps the team of health professionals create a long-term exercise program after the patient completes rehabilitation.
• Nuclear stress test
  An advanced type of cardiac stress, a nuclear stress test uses permissible levels of radioactive substances to assess heart functions using a cardiac imaging scan. The scan helps evaluate the amount of blood flow to the heart at rest and after stress. A decreased blood flow indicates a possible blockage in one of the multiple arteries. A nuclear stress test can also determine whether the patient needs stents or a bypass surgery and can help avoid invasive heart tests like cardiac catheterization .

What are the preparations before a cardiac stress test?
Although it depends on the type, a basic cardiac stress test lasts about 20 minutes. Stress tests requiring nuclear imaging or electrocardiography may last for three hours. Doctors may advice the following before taking the test:

• Avoid caffeinated beverages like coffee, tea, or energy drinks and other intoxicating substances at least 24 hours before testing.
• They may also advice fasting for patients undergoing nuclear stress test. Such patients may also be advised to fast post the nuclear test.
• Doctors may also advice wearing comfortable, lightweight clothes and shoes when taking a stress test on a treadmill or stationary bicycle.

How are the test results evaluated?
After the doctor asks the patient to stop exercising, they will examine how well their heart rate recovers post exertion.

• If the difference between their peak heart rate and heart rate 60 seconds after the exercise is less than 12 BPM, then it is evaluated as an abnormal performance.
• If the heart rate is more than 12 bpm in a walking recovery, the results are considered as normal.
• It is classified as abnormal if the heart rate is less than 18 bpm in recovery lying on back, whereas if it is more than 18 bpm in recovery lying on back, it is normal.

Apart from this, the results are evaluated using a metabolic equivalent or METS that equates oxygen uptake in milligrams.

• Patients with a METS score of less than 5 may have an underlying heart condition. Further evaluation may be required.
• A METS score between 5 and 8 is considered as fair performance and may require both, further evaluation, and changes in lifestyle.
• A 9 and above METS score indicate a healthy heart functioning.