7 Key Facts to Understand About Cardiac Stress Test

By Dr. Ramji Mehrotra in Heart & Vascular Institute

Apr 20 , 2023 | 6 min read


Until some time ago, it was quite common for middle-aged males to get acardiac stress testas part of their annual physical examination. The procedure is an important tool for detecting or diagnosing chest pain. Thestress testis especially useful in older people who have an increased risk of heart disease.

A stress test of the heart can assess how well or badly the heart can function during physical activity. It’s a reliable method for assessing cardiac health status. When a person is sitting down, their heart isn’t working hard. Only when they go for a swim or a run, the heart increases its workload.

What is a Heart Stress Test?

A heart stress test involves walking on a treadmill to make the heart work progressively harder. Various parameters are checked while the person walks. An abnormal result in the stress test indicates a risk of significant coronary artery disease.

How Does a Stress Test Assess Cardiac Function?

A cardiac stress test makes the heart pump harder and quicker. When a person walks on a treadmill or rides a stationary bike this scenario is created. The way the heart responds to the increased workload can be known by measuring blood pressure, heart rate, oxygen levels and electrical activity in the heart. The measurements are compared with others in the same age group.

Why is a Stress Test Needed?

The cardiac stress test can detect congestive heart failure, coronary heart disease and problems with the heart valves Asymptomatic individuals with high risk to develop heart condition can be detected using stress test. Individuals in select professions such as pilots and professional athletes are mandated to undergo periodic cardiac stress tests as a standard practice.

Who Needs a Stress Test for the Heart?

People who have high risk to develop heart illnesses are advised to undergo astress test. They may not have symptoms and signs like:

  • chest pain
  • rapid or irregular heartbeat
  • difficulty in breathing
  • people who feel dizzy or lightheaded often but have higher chances of carrying undetected heart condition.
An exercise stress test is also useful:
  • to determine how existing heart treatment is working
  • in people who have a history of heart disease

What are the Various Kinds of Stress Tests Available?

Stress test with exercise

This test is prescribed most often and is the basic form of a cardiac stress test. Here the person walks on a treadmill or rides a stationary bike. The speed and elevation of the treadmill are adjusted according to the person’s fitness and the changes in ECG are noted.

Stress echocardiogram with exercise

In this test, an echocardiogram machine provides an ultrasound of the heart before the start of the exercise and during it. Sound waves are used to study blood flow through the valves of the heart and the muscles that pump the heart.

Stress test using nuclear imaging

This is anadvanced cardiac stress testthat uses low levels of radioactive material and cardiac imaging to study heart functions. It enables the cardiologist to compare the blood flow to the heart muscles before and after an exercise. In this way, any reduction in blood flow will mean a blockage in one or many vessels supplying the heart. A nuclear cardiac stress test is useful:

  • To assess the degree of blockage in coronary artery disease.
  • To judge whether previous treatments such as stents or bypass surgery are working effectively.
  • As a substitute for invasive heart tests like catheterisation.
  • As a fitness test before any other surgery.

Stress test during cardiac rehabilitation

A cardiac rehabilitation stress test is a supervised process to help people with existing heart disease lead a more active life. It is tailored to suit individuals according to their capabilities. The progress of the individual is monitored regularly through a long-term exercise program. It is recommended as a post-surgical programme, or even after a heart attack. This programme is beneficial for people who have existing heart diseases like congestive heart failure and abnormal heart rhythm, or those who use a pacemaker.

Why is a Stress Test Done for the Heart?

Aims of the test

A cardiac stress test is a diagnostic test for people with suspected coronary artery disease and for providing prognostic information for people with existing disease. It is used to determine functional capacity, assess the probability and extent of disease, and assess the risks and effects of ongoing treatment.

Limitations of a stress test

The cardiac stress test cannot show the cardiologist the precise region where blood flow is affected. To determine this, invasive testing is required.

What is the Importance of Determining Eligibility for an Exercise Stress Test?

A medical test of any kind, especially an exercise stress test may sometimes show results that recommend further testing which may not be needed. Further tests like a coronary angiogram come with their complications. The cardiac specialist may use his/her judgement and decide not to advise routine stress tests that involve extensive costs and further treatment. A person’s age, family and medical history, presence of symptoms and risk factors like diabetes, high blood pressure, and habits like smoking determine whether the cardiologist wishes to test or not.

What About Exercise Stress Testing in Women?

Heart disease in women presents differently than it presents in men. This is a challenge for doctors to detect heart disease at an early stage in women. Stress tests are therefore customised based on the sex and age of individuals. For instance, nuclear tests that involve radiation exposure will not be recommended for women of childbearing age.

How Safe is Cardiac Stress Testing?

There are no major risks when performing an exercise stress test. The individual undergoing a cardiac stress test is under supervision at all times during the procedure. They are observed both by the physiologist and a cardiologist who is trained to provide emergency treatment should the need arise. The person undergoing the stress test can stop the test at any moment he becomes uncomfortable. A stress test should not be performed on individuals who have had a heart attack within the past few days, those with uncontrolled high blood pressure, or individuals experiencing acute heart disease with pain.

Frequently Asked Questions

1. What do normal stress test results mean?

A normal test result may vary depending on the purpose of the test. When the results show that the heart is healthy with adequate blood flow, it could mean that the symptoms the person experienced were due to anxiety. Some may get the go-ahead for other surgical procedures. For people who are already receiving treatment, a normal result indicates that their treatment has been successful.

2. What happens if my exercise stress test results are abnormal?

An abnormal result is usually a sign of heart disease. If the condition is mild, the cardiologist may suggest lifestyle changes and medicines. In case there are abnormalities early in the test or if large portions of heart tissue are affected, the cardiologist will advise cardiac catheterisation, angiography or further tests like the nuclear stress test.

3. How long does a cardiac stress test take?

The basic stress test typically takes around 15 minutes to complete, with the additional time needed for preparation before the test and recovery after the test.Other tests which involve nuclear imaging or echocardiography require up to 3 hours.

4. Can a stress test show a blockage?

An exercise stress test is used to determine if any of the coronary arteries that supply blood to the cardiac muscles contain fatty deposits or plaque.A normal test result indicates no significant blockage. Significant coronary artery disease refers to 70% or greater blockage of arteries. An abnormal result indicates 70% or greater blockage. Further testing is usually done in case of abnormal results.

5. What is a good score on a stress test?

The DTS (Duke Treadmill Score) is universally accepted for risk assessment of persons who have undergone an exercise stress test. The range of scoring is from +15 to -25.

  • Persons with a score >= 5 are considered low risk with a 5-year survival rate of 97%
  • Persons who score <=-11 are regarded as high risk with a 5-year survival rate of 65%
  • Between these two scores is the intermediate risk category with a 5-year survival rate of 90%.