What is the Corus™ CAD test?
The Corus CAD test is a new blood test to assess coronary artery disease (CAD) that may be causing a blockage in your artery. The test measures key biological processes such as inflammation (the body’s response to injury) that contribute to atherosclerosis the buildup of fatty plaque on the walls of the arteries.
When combined with an assessment of your other CAD risk factors, the Corus CAD test helps your doctor determine whether you have coronary artery disease. By identifying patients who have a high likelihood for having a significant blockage in the coronary arteries (arteries narrowed by 50% or more), the test enables your doctor to make better decisions about lifestyle changes and treatments to prevent coronary artery disease progression.
The test is performed through a simple blood sample taken from a vein in your arm. The blood sample can be conveniently collected in your healthcare provider’s office.
How does the Corus CAD test work?
The Corus CAD test measures the activity of genes in response to the biological processes that lead to the formation of blocked arteries. The Corus CAD is a gene expression test and not a genetic test. Genetic tests look directly at the genes that make up your DNA. At the time of birth, you are born with DNA that stays the same throughout your life and does not change. A gene expression test, however, is different in that it measures the activity of genes in your body that may impact whether or not you have a certain disease today.
Standard genetic tests can tell if you are at risk for having certain diseases someday, but they cannot tell for sure whether you will ever develop a disease. This is because a disease process is not determined by your genes alone, but is also influenced by your environment including your diet, physical activity level, stress, and other lifestyle factors.
Instead of looking at the genes themselves, gene expression tests look at how your body is using your genes right now. The Corus CAD test measures the amounts of RNA, which translates the information in your DNA into proteins (the basic building blocks of the body). By measuring the amounts of specific types of RNA involved in your body’s response to atherosclerosis, the test provides information about the current health of your arteries.
Is the Corus CAD test accurate in women?
It is well known that heart disease affects women and men differently. Women tend to develop heart disease later in life than men, and often have different heart attack symptoms than men. These differences are likely to be caused, in part, by biological differences between the sexes that affect the progression of coronary artery disease as well as how it produces symptoms. Therefore, it is important that tests to diagnose heart disease take the differences between women and men into account.
The Corus CAD test is the first noninvasive test for coronary artery disease that accounts for biological differences between the sexes. During development of the test, researchers discovered that the types and amounts of RNA found in people with blocked arteries were somewhat different in women compared with men. So when a patient’s blood sample is analyzed for the Corus CAD test, different factors are used in women to ensure the test results are as accurate as possible.
Who might have the Corus CAD test?
Your doctor may order the Corus CAD test if you have stable chest pain (chest pain that occurs during activity and goes away with rest) to determine if your symptoms may be due to coronary artery disease.
The test may also be used in women who do not have chest pain, but are at high risk for coronary artery disease because of other characteristics or conditions that make them more likely to develop the disease—called risk factors. A woman with more than two of the following risk factors may have the Corus CAD test ordered to evaluate her likelihood of having a coronary blockage:
- Age over 60 years
- High cholesterol
- High Blood Pressure
- A family history of heart disease
Who should not have the Corus CAD test?
Certain medical conditions other than coronary artery disease can also influence the type of biological processes measured by the Corus CAD test. The Corus CAD test is not intended for use in women who:
- Have diabetes
- Have already had a heart attack
- Have undergone an invasive procedure to treat CAD (such as angioplasty and stenting or bypass surgery)
- Have long-term (chronic) inflammation caused by rheumatoid arthritis or other conditions
- Are taking steroid medications, chemotherapy, or drugs to prevent activity of the immune system (immunosuppresants)
How is the test performed?
The Corus CAD test is performed through a simple blood sample taken from a vein in your arm. The sample can be taken in your doctor’s office, and no fasting or other special preparation is necessary.
Your blood sample will be sent to a specialized laboratory for analysis, and the test results will be sent to your healthcare provider within 3 business days. Your healtcare provider will discuss the results with you.
What do the results mean?
The Corus CAD test reports a score from 1 to 40 showing your likelihood of having a significant blockage in your coronary arteries, based on a clinical trial conducted by CardioDx. The higher your Corus CAD score, the more likely you are to have a blocked artery. The lower your score, the less likely you are to have a blocked artery.
On their own, the results of the test do not mean your heart disease should be treated in a certain way. Instead, your doctor will consider the results along with other clinical information about you and develop a management plan based on their overall assessment.
What are the risks of the test?
The Corus CAD test is a safe and simple blood test that carries no major risks of the testing procedure. Unlike other tests that use advanced imaging of the arteries to diagnose blockages, the test does not involve exposure to radiation or imaging agents.