WHAT IS CARDIOPULMONARY EXERCISE TEST (CPET)?

Cardiopulmonary Exercise Test (CPET) is the only non-invasive exercise stress test that assesses heart and lung function in real-time during exercise. Your heart and lungs work together to deliver oxygen to your working muscles where it is used to make energy; and to remove carbon dioxide from the body. CPET measures the amount of oxygen your body is using, the amount of carbon dioxide it is producing, your breathing pattern, and electrocardiogram (EKG) while you are riding a stationary bicycle.  


This data undergoes expert analysis in the data center where exercise capacity is quantified using MET-TEST powerful proprietary pattern recognition software, and the mechanism of patient symptoms is prioritized. 


This is a much more detailed level of insight and feedback to the ordering physicians than a traditional treadmill stress test. Besides detecting problems in the heart and lungs, serial testing with CPET is also used to monitor changes in your disease condition and response to therapeutic interventions such as exercise and medical therapy to ensure long-term health is headed in the right direction. More information on Treadmill vs. CPET

WHAT CONDITIONS CAN BE DETECTED AND MONITORED BY CPET AND NOT TRADITIONAL TREADMILL STRESS TEST?

The traditional treadmill stress test can only detect ischemic heart disease of the large blood vessels, and it is not very accurate at doing this. Not only does a CPET do a better job of detecting ischemic heart disease, but it can also pick-up many other conditions that the treadmill stress test cannot.


Heart, lung, and metabolic conditions can cause shortness of breath, chest pain, fatigue and overall exercise intolerance.  CPET is the only test that can simultaneously determine which of these systems is causing the problem:



HEART

Coronary artery disease, heart failure and valve disease will impair ability to increase cardiac output with exertion and hence cause symptoms.  CPET is frequently abnormal when routing cardiac testing in the cardiologist’s office is normal.

CHRONOTROPIC INCOMPETENCE

Inability to increase heart rate appropriately during exertion.

LUNGS

Inability to ventilate air or poor circulation in the lungs can cause shortness of breath.  In many cases, CPET will reveal abnormalities in lung function when resting pulmonary function testing (PFT) are normal.

DECONDITIONING

Poor cardiovascular fitness that can be improved with exercise.

MUSCLE METABOLIC DISORDERS

Inability of the muscle cells to use oxygen from the bloodstream to produce energy for the working muscle tissues (example: mitochondria disorders, McArdle’s disease, enzyme deficiency).

EFFORT

Poor effort is easily detectable with appropriate interpretation on CPET.

WILL I GET THE SAME RESULTS FROM CPET AS I WOULD WITH TREADMILL AND NUCLEAR STRESS TEST?

No, other tests use fewer measurements and assess cardiac and lung function separately. A treadmill stress test only looks at a specific part of your ECG during exercise that can indicate heart disease. However, in many people with heart disease, this ECG abnormality never appears. Nuclear stress testing uses a radioactive chemical that is injected into the bloodstream to estimate how blood flows around the heart. Pictures are taken with a special camera before and after exercise to show any abnormalities. This can detect an abnormality in main, large (macrovascular) blood vessels around the heart; however, it does not show any abnormalities in the small (microvascular) blood vessels of the heart. Nuclear stress testing can also miss patients with blockages in multiple blood vessels, or in blood vessels not easily seen by the camera due to their position on the heart. The CPET is not an imaging test, but a physiological test. It measures how your heart, lungs, and muscles are functioning during exercise. CPET takes into account multiple physiological variables that might limit your ability to exercise. No other test exists that can measure heart, lung, and muscle function all at once.

HOW IS A CPET PERFORMED?

Unlike a traditional stress test, the CPET is performed on a stationary bicycle, which is safer than a treadmill. Many patients feel more comfortable riding the bicycle than walking on a treadmill as they are seated and can stop when needed. The following equipment will be worn during the test:


Face mask: This monitors the oxygen used, carbon dioxide produced, and the breathing pattern. The mask is placed over the mouth and nose. It does not restrict breathing and you will only be breathing-in air from the environment.


Electrocardiogram (EKG): Ten stickers will be placed on your chest with monitoring wires attached. This is used to monitor your heart rate and rhythm.


Blood pressure cuff: Your blood pressure will be taken multiple times during the test.


Before exercise begins, you will be asked to perform 2 lung tests. The results of these tests will be compared to your breathing during exercise. Your technician will then fit the required equipment to you and help you get on the bicycle. While you are resting on the bicycle, your technician will explain the testing procedure in greater detail. At the end of the rest period, you will be asked to begin pedaling lightly for a few minutes, to warm up. The resistance on the bicycle will then slowly become harder and harder as if you were going up a hill that keeps gently getting steeper and steeper. The test will continue until you are giving your maximum effort and can no longer continue.


To get the most accurate results for your doctor, it is important that you give your best effort for as long as you possibly can. If you do not give a maximum effort, your test may be “indeterminate” and your doctor will not have the most accurate information to help you. The exercise work load will be adjusted on an individual basis to enable each person give his or her best effort. Your technician will keep encouraging you to continue to get your best effort until he or she sees that you cannot continue. However, if your technician notices that you are experiencing certain symptoms the test will be immediately stopped. After the test is over, your technician will ask you to pedal slowly and gently to cool down while he or she continues monitoring your vital signs.


The actual time it takes to perform the test, from the time you get on the bike, through the exercise portion and recovery will be between 15 and 25 minutes. However, you will only be asked to exercise at a hard intensity for about 3 to 4 minutes.


For best results:

  • Give your best effort and exercise for as long and hard as possible
  • Keep your legs moving at the same speed for the entire test, even when it is difficult
  • Avoid speaking during the test unless you have discomfort or pain
  • Let the technician know if you have discomfort or pain at any point during the test

HOW OFTEN SHOULD I HAVE A CPET?

With progression of coronary disease, peak cardiac function (Peak VO2) will deteriorate, so serial CPET testing serves as a key tool to help monitor changes in cardiac health over time. Improvements can be seen within six months of implementing lifestyle and medical therapies, but at the very minimum, patients with an abnormal CPET should have one done annually to follow the course of their disease and confirm response to therapeutic interventions.

Patients started on beta-blocker medication may need to repeat their test in one month to determine the most effective dosage for optimizing cardiac function (since this will vary among individuals).


The goal in every person is to increase Peak VO2 from baseline by 10% or more per test until the underlying cardiac dysfunction pattern is completely normalized (as seen in the case study Here).


Share by: