Cardiac Tests Go Beyond Cholesterol
By John Leighty
February 14, 2005
For many years, a good cholesterol number has been akin to earning an A on the heart health report card. But today, cardiac screening is moving beyond cholesterol counts and lifestyle assessments to detect the risk of heart attack.
An emerging indicator of risk is CRP, or C-reactive protein, a sign of low-grade inflammation in coronary vessels that can signal heart disease risk even in seemingly healthy people.
While high cholesterol, high blood pressure, smoking, heredity, obesity, and a sedentary lifestyle are pegged as the prime risk factors for heart disease, nurses are finding highly sensitive CRP tests to be a valuable new tool in patient evaluations.
Increased levels of CRP, found in trace amounts in healthy people, are viewed by some clinicians as the key biomarker for the risk of heart attack, surpassing results obtained by testing total cholesterol, low density lipoprotein (LDL or “bad”) cholesterol, or homocysteine.
“If a patient has risk factors for heart disease — smoking, obesity, inactivity — and the cholesterol levels are non-favorable, well that’s four markers and it’s a high score,” says Teri Hernandez, RN, a clinical research nurse at the University of Colorado Health Sciences Center at Fitzsimons, Colo. “But if the CRP levels come in high, that means a lot more in telling me that the person needs to make changes.”
Detection and education
Early detection of coronary heart disease, the leading cause of death of both men and women, is a major goal of researchers, says Hernandez. Tests that signal cardiovascular dangers give nurses an opportunity to work with patients to reduce risk factors and increase longevity through heart-healthy lifestyle changes and medications.
At Southern California’s Northridge Hospital Medical Center, cardio CRP tests are often used to look for inflammatory symptoms, usually in conjunction with cholesterol screening, says Sonni Logan, RN, BSN, the clinical supervisor for the cardiac cath lab. While cardio CRP tests are fairly new and still somewhat questionable, they are a predictor of inflammation of coronary arteries and can indicate the risk of a heart attack even when cholesterol readings are normal, says Logan.
“One reason we jumped aboard is because high cholesterol levels are only present in half of the people who have heart attacks and we needed a more sensitive test to assess risk,” says Logan, adding that cardio CRP tests started at Northridge in 2001.
Logan’s been supervisor of the clinical cath lab for four years, after having spent 10 years in the ICU and 11 in the ER at Northridge. “Even in the ER and ICU I was always considered the heart nurse, so I came here with a lot of skills in that area,” says Logan. “It feels good to offer that experience to patients.”
Logan says patients coming to the cath lab are a captive audience and this gives nurses the opportunity to explain test results and impart heart-healthy advice. “We take the bull by the horns and say, ‘You’ve got issues here,’” she says. One risk factor reaching epidemic proportions locally and nationally is obesity and, regardless of test outcomes, overweight patients are urged to watch their diet and exercise more, she says.
“There’s an old adage: Just moderate,” says Logan. “Go up the stairs instead of taking the elevator. Take a parking space where you have to walk further. And stay away from fatty foods. They may add taste, but they don’t benefit your health.”
Hernandez, a nurse for 11 years, 10 in cardiovascular care, also recalls enjoying her role in educating patients in a cardiac rehab program at Baylor University Medical Center in Dallas. “I like to think that every patient would want to review their heart attack risk factors. I used to walk around with a big stack of pamphlets and articles. It was prime time for education.”
More study needed
Hernandez is now working toward a PhD at the Colorado teaching hospital campus, participating in two research projects involving CRP with Bob Eckel, MD, a professor of medicine in biophysics and physiology and the division of endocrinology, metabolism, and diabetes.
One study looked at the short-term effects of simvastatin (Zocor), a drug that lowers LDL cholesterol and can also lower CRP. In people with high lipid values, it took 14 days to bring CRP levels down. The second study looked at the effects of the statin on people with Type 2 diabetes, who also have a higher risk of heart events. Preliminary data shows lipid levels dropping significantly within two weeks, with positive results by day seven.
There are still no studies, however, that show lowering CRP reduces the risk of a heart attack, notes Hernandez. High levels of CRP are also caused by obesity, rheumatoid arthritis, diabetes, and cancer, which is one reason Hernandez doesn’t see CRP being effective as a stand-alone test. Also, for younger people and those with no family history of heart disease, a good cholesterol panel test score is usually an accurate predictor of low risk, she says.
For nurses seeking additional information about tests for heart disease, Hernandez recommends going to the American Heart Association’s position paper posted on its website, www.americanheart.org. The same site has a 13-page scientific paper by the AHA and Centers for Disease Control, “Markers of Inflammation and Cardiovascular Disease,” available for downloading.
Patricia Armstrong, RN, FNP, cardiac educator at Rogue Valley Medical Center in Medford, Ore., says CRP tests are rare in inpatient acute care settings because CRP is a predictor of an event that has already occurred. However, patients who have had a coronary event or stent are given statin medications if they can tolerate them, and these do reduce CRP levels.
Armstrong also works in a primary care clinic and said for patients with borderline high cholesterol, a CRP test showing signs of inflammation of coronary arteries can help persuade patients to make some healthy lifestyle changes or take medications that will lower the lipid count. Accepted CRP levels for low risk of developing cardiovascular disease is a reading below 1.0 mg/L; average risk is between 1.0 mg/L and 3.0 mg/L; and high risk is above 3.0 mg/L.
“It’s a very good motivator to have that CRP number,” says Armstrong. “It’s not an absolute indicator of cardiovascular disease, but it does add to the total picture and I’ve used it that way.”
At the Arizona Heart Institute in Tucson, clinical manager Teresa Capriotti, RN, BSN, says CRP testing is done selectively, usually with patients who are asymptomatic but have a family history that qualifies as a risk factor, usually a father with heart disease before age 45 or a mother before age 55.
“We tend to stick with the gold standard – a total lipid panel that measures total cholesterol and a breakdown of HDL (good) cholesterol and LDL (bad) cholesterol,” says Capriotti. Patients with various degrees of risk are put on diet and exercise routines and if needed, given Lipitor or another cholesterol-lowering statin, she says.
Capriotti says the CRP test only shows the level of risk from inflammation, whereas patients with abnormal cholesterol readings will definitely be in danger from coronary cardiovascular disease. A cardiac nurse for more than 20 years, Capriotti says shealso seen obesity become much more prevalent and a major risk factor, challenging nurses who are trying to help patients improve their lifespan.
President Clinton
“We are talking all the time about diet and exercise and that they really must maintain a healthy balance in the foods that they eat,” says Capriotti. She says people do seem to understand the minimum risk factors and that the institute got a 30% increase in calls from concerned people when the seemingly healthy former President Bill Clinton was hospitalized for heart surgery and had a battery of tests, including CRP.
“Men and women who were asymptomatic were coming in for tests,” says Capriotti. “We’re still getting calls.”
The Clinton emergency, which revealed three almost totally clogged arteries after he complained of chest pains, shocked some leading cardiologists who have called for more aggressive use of preventive screening, such as blood marker tests and wider use of a noninvasive and costlier diagnostic test known as the coronary calcium scan. About 2.1 million Americans have heart attacks each year, and 50% of these attacks occur without symptoms or diagnosed high-risk factors, according to the American Heart Association.
Gail Pritchett, RN, a specialist in cardiac rehabilitation at Southwest Medical Center in Vancouver, Wash., says clinics there offer a “risk factor profile” that includes a cholesterol panel, CRP test, and a check of homocysteine levels. Family history and other major risk factors are also looked at on an individual basis.
She says the best evidence-based treatments are used, depending on the patient profile. This includes the use of statins or combinations of medications to reduce high cholesterol and CRP levels and prescription-strength folates that easily treats high homocysteine levels.
“CRP is an important piece of the risk factor panel,” says Pritchett, a team manager for 12 nurses at a cardiac rehab center. “People who don’t have high cholesterol can have elevated CRP that may be the first sign that something’s going on with the life of the arteries.”
A recent study by Duke University researchers has also come up with a new heart attack risk factor — negative emotions. Depression, anger and hostility were found to trigger high levels of CRP, which isn’t surprising to Pritchett.
“Anger and hostility could play a part,” says Pritchett, adding that adrenaline from stress is also known to raise CRP levels. “Everything is interconnected when it comes to keeping the heart healthy.”
John Leighty is a freelance writer.