New Test For Heart Disease
PHOENIX, Ariz. (Ivanhoe Newswire) - Coronary artery disease is the leading cause of death worldwide. While there have been great strides in preventing it, the hardest part has been figuring out who is at high risk, especially since men and women often have different symptoms. Now, a new sex-specific blood test is helping answer that.
Whether challenging herself to a game of ping pong or taking her dog "Puppy" out for a walk, Mandy Welsheimer tries to stay active especially since she has a family history of heart disease.
"Both my grandfathers had coronary artery disease; one died of a heart attack when he was 56, and the other one ended up with a pacemaker," Mandy told Ivanhoe.
When she began to have chest pain, she decided to take a first of its kind blood test to determine her risk.
"This test actually looks at what's going on right now at the molecular level in your particular body and then can tell us what your chance of having a problem is right now," Dr. Alan Grossman, Medical Director of Non-Invasive Cardiology at the Heart and Vascular Center of Arizona, told Ivanhoe.
The Corus CAD test works by measuring the activity of 23 genes in your blood that change when there's a blockage in the arteries. The test comes up with a score indicating your likelihood of a blockage and is the first to be sex-specific. Two multi-center trials found it more accurate than the current standard, nuclear stress testing, with a 96 percent negative predictive value versus 88 percent. Meaning if the test says you don't have CAD, there's a 96 percent chance you don't have a major blockage.
"It certainly is a huge relief for a lot of patients," Dr. Grossman explained.
Mandy's score came back low.
"It put my mind at ease," Mandy said.
Dr. Grossman said the new test can help doctors decide if invasive approaches are necessary for patients. The test is currently covered under Medicare.
BACKGROUND: Coronary arteries have a very important function of carrying blood to the heart, but for people with coronary artery disease (CAD), these arteries are damaged or diseased causing blood flow to the heart to be restricted. Atherosclerosis, which is the hardening of arteries, is a common cause of these blockages because cholesterol-containing deposits called plaques begin to build up on the inner wall of the artery. Because the heart is not getting enough blood and oxygen, coronary artery disease can lead to angina, and if the blood flow is completely blocked, heart attack. (Source: www.mayoclinic.com)
SYMPTOMS: Coronary artery disease builds over time, so symptoms may not be apparent until the disease has progressed. Possible signs of coronary artery disease are:
- Angina (most common symptom)
- Shortness of Breath
- Heart Palpitations
- Extreme Weakness
- A Faster Heartbeat (Source: www.clevelandclinic.org)
RISKS FACTORS: In order to prevent coronary artery disease before real damage is done to the heart, people need to know the common risk factors for the disease. These risk factors include: smoking, diabetes, high blood pressure, a family history of heart disease, and high levels of LDL cholesterol. Women are also at an increased risk of CAD after menopause while men's CAD risk rises after the age of 45. Lifestyle changes can help to control some of these risk factors, such as smoking and high cholesterol, but others are hereditary. People with a family history of heart disease should monitor their heart health closely and live a healthy lifestyle. (Source:www.heart.org)
NEW TECHNOLOGY: When people are concerned that they may have CAD or a coronary blockage, doctors would traditionally use X-rays, monitored exercise tests, or invasive procedures to see if there is any problem in the heart. However, these tests can be unpleasant and sometimes do not return definite results. Now, the Corus CAD blood test can assess whether a person has coronary artery disease in a faster and simpler manner without exposing patients to any radiation. The Corus CAD is especially beneficial in diagnosing women, who can sometimes have false positives with other tests, because it is the first test to take key biological differences between the sexes into account. For the test, a blood sample is taken and then the test measures the activity of specific genes that change when there is an arterial blockage. The test then scores the likelihood of the patient having a blockage. Diabetics, people who have already had a heart attack, and people using steroids, immunosuppressive agents or chemotherapeutic agents should not use the Corus CAD. (Source: www.cardiodx.com)
Alan M. Grossman, MD, FACC, FASNC, Medical Director of Noninvasive Cardiology at the Heart and Vascular Center of Arizona, talks about a blood test for evaluating people's risk of coronary artery disease.
We are talking about the Corus CAD test today. Can you tell me about it?
Dr. Grossman: Corus CAD is a simple blood test that can be drawn in my clinic. It is a novel way of looking at what goes on in people's arteries. So, it's a good way for evaluating people who might have coronary artery disease that are having symptoms of chest pain. It takes a different approach than what we normally use to evaluate people for heart disease. We look at gene expression and what that means is the test looks at twenty-three genes, which are pieces of the DNA that we all have. These genes are used and copied into something called RNA, which can then be drawn from your blood. RNA is what tells the cells in your body how to carry out the message that the DNA is giving, and these genes have been associated with coronary artery disease and plaque buildup. So based on this simple blood test, we can then use the results to determine what someone's chance of having a coronary blockage at that present time is. This is different from gene tests or other genomic tests that basically are looking at whether or not you have a gene mutation. The difference is that when you have a mutation, it basically means you have this problem in your DNA that might lead to a problem in the future. This test looks at what's going on right now at the molecular level in your body and then tells us what your chances of having a problem right now are.
Before this test, what were a patient's options if they wanted to find out if they may have coronary artery disease?
Dr. Grossman: We are currently using other kinds of noninvasive testing, which are considered mainstream and we do all the time. That would include stress testing, either by itself where someone would walk on the treadmill or sometimes with imaging where we actually exercise somebody and then inject them with the radioactive compound that tells us what the blood flow is like inside the heart muscle within the arteries. The most extreme case would be a heart catheterization where we would actually have to do a more invasive test in which we inject IV dye directly into the arteries so we can actually see under an x-ray machine if they have a major blockage. Sometimes we can also do coronary calcium testing and CT CAT scans to do the same thing. The difference between all those tests and Corus CAD is that some of them are physiological tests, some look at anatomy, but for the most part they involve radiation exposure to the patient. In the case of a heart catheterization, it involves doing a more invasive test that could potentially have complications. That said there are limitations from some of the noninvasive tests that we often use such as the stress test. In particular, there are instances where you might do a test on someone and the test may be abnormal, but it may not truly be abnormal. On the other hand, you may be underestimating a problem that someone might have.
Do you have some figures that might show the accuracy of this test versus traditional types of tests?
Dr. Grossman: There were clinical trials that have looked at these two tests. The standard test we would often use would be a nuclear stress test, which is something we employ very commonly even in this practice. It has a pretty high sensitivity, meaning it's a very accurate test in the mid to high 80% range for accuracy. It also has what's called the negative predictive value that's around the same range, which means if the score is normal the chance of you having a problem is pretty low. There was a clinical trial comparing nuclear stress testing to the Corus CAD testing and the Corus CAD test was found to have higher sensitivity and also a higher negative predictive value, meaning it was even slightly more accurate than nuclear stress testing in certain patient populations.
Do you have a percentage?
Dr. Grossman: In that trial the nuclear stress testing had an 88% negative predictive value and the Corus CAD test had a 96% negative predictive value. What that means is if your tests come out saying that you don't have a disease process, then in the case of the Corus CAD test there's a 96% chance that you don't have a major blockage based on the blood test.
Is that a huge relief for some of the patients?
Dr. Grossman: Yes. It certainly is a huge relief for a lot of patients and in clinical practice we often can use that in a patient to potentially prevent them from undergoing other tests that may be unnecessary or potentially expose them to side effects or radiation.
Who is a good candidate for the test?
Dr. Grossman: The test is useful pretty much in all different demographic areas. It's even more accurate in female patients, especially if your score is normal to low on this test; it is extremely accurate in that subset of patients. It has been utilized in other clinical trials, especially at the initial clinical trial, which was called the PREDICT Trial, and it demonstrated that when you do this blood test it could reclassify a patient. What I mean by that is if you thought the patient had sort of a low, intermediate, or high chance of having a coronary blockage, the blood test often times would reclassify them into a different category. So for instance, if I thought a patient had an intermediate chance of having a problem it can sometimes turn out that they really don't have much of a problem, or they have a much bigger problem that we had underestimated.
I know this is a gender specific test and it's the first of its kind, right?
Dr. Grossman: Correct.
Can you talk about why that's really important?
Dr. Grossman: Most of these noninvasive tests that we're currently doing are basically gender neutral. We just do a stress test on a patient, and when we do it with imaging there are certain things that can make the pictures more difficult to interpret. In female patients often times the symptoms are not as typical as what would be considered normal in a male patient. It was traditionally thought that the typical symptoms of crushing chest pain and other symptoms were more commonly found in male patients, but what we found in the literature and after examining this for decades is female patients often times have symptoms that are atypical but may still have a problem. When you have a female patient with atypical symptoms and you're doing a test on them which may potentially have what's called a false positive. It can therefore be very challenging to determine how to interpret the data and give the right advice to a patient. Since this test is gender specific, the algorithms are slightly different between men and women. When you couple that with a highly accurate test, especially in female patients, it could prevent you from having a situation where you get a test that's falsely abnormal and then further discussions about doing more invasive tests would come up.
Could it potentially be lifesaving then?
Dr. Grossman: It can be lifesaving. I've seen it in patients where we've reclassified them; patients that we thought were sort of low to intermediate and then the score becomes very abnormal. So, it may make somebody want to investigate this further and prevent further problems from happening.
How big of a breakthrough would you say this is?
Dr. Grossman: I'd say it's a very large breakthrough because it really changes the paradigm for how you're looking at a patient with coronary disease. It's really the first test to my knowledge where you're evaluating what's going on at the molecular level in the patient right when you're drawing blood in the office and then help determine what their chance of having a blockage in an artery is right now.
I would say that with regard to using this as a test in a patient with chest pain or symptoms suggestive of coronary disease, it can be utilized initially to evaluate that patient. If it comes back that the score is very low, then depending on what one's comfort level is with that information, one could potentially use that as a way to decide whether or not to investigate further. It always comes down to what is going on clinically with the patient and you need to really talk to the patient and get a history.
Listening to you, it sounds like if it came back low you would not do more tests?
Dr. Grossman: Yes, if it comes back low I would be very comfortable telling a patient they have a low risk of having a major problem. That's very reassuring to most people when they get that information. It's useful adjunctively as well; a lot of times if someone's had other kinds of testing that was abnormal, this can help us to decide whether or not we truly believe that information based on reclassifying them with tests.
If I wanted to come in to take the test to see if I had a likelihood of developing coronary disease, would I be able to do that?
Dr. Grossman: It's for symptomatic people, so it would be someone with symptoms that would be suggestive of coronary artery disease or atypical symptoms that could be consistent with coronary artery disease or blockage in an artery.
Does insurance cover this?
Dr. Grossman: It's covered by Medicare. For qualified patients who may not have coverage, the company offers a generous financial assistance program.
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