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If you’re worried about your risk for heart disease, there’s something you should know: More tests do not necessarily add up to a better diagnosis. According to a new practice guideline, a basic risk assessment that accounts for such factors as cholesterol level, blood pressure, age, sex, family history, and whether you smoke or have diabetes is still the strongest tool a doctor can use in predicting the likelihood of heart disease. Beyond that, most tests that claim to predict heart disease risk are helpful only in selected cases.
Jointly developed by the American College of Cardiology and the American Heart Association, the new guideline appears in the December 14/21, 2010, issue of the Journal of the American College of Cardiology and the December 21, 2010, issue of Circulation: Journal of the American Heart Association. It outlines which diagnostic tests are most useful in assessing cardiovascular risk in people who have no obvious signs of heart disease—and which tests do little to clarify the health picture.
After reviewing more than 400 scientific studies, the expert panel determined that only a global cardiovascular risk score and family history were essential for everyone, starting at age 20."There’s strong evidence that the basic risk assessment we’ve been advocating for years has a very, very strong ability to predict risk," said Philip Greenland, M.D., a professor of medicine and preventive medicine at Northwestern University Feinberg School of Medicine in Chicago. "When new tests compete for attention we have to ask, ‘Do they add any new information?’"
Beyond that, the expert panel weighed whether new diagnostic information would change a physician’s treatment plan or a patient’s health habits, and whether that change would be powerful enough to improve health outcomes. As a result, many tests were found useful only in intermediate-risk patients—those with a 10 to 20 percent risk of developing heart disease within 10 years. That’s because in low-risk patients, additional diagnostic tests seldom add useful predictive information, while in high-risk patients, the global risk score and family history make it obvious what the physician should do next, and additional tests don’t change that.
Even tests that have captured intense public interest, such as C-reactive protein and coronary calcium scoring, received nuanced and limited recommendations that reflect the data currently available from clinical studies.
"These guidelines are based on scientific evidence," Dr. Greenland said. "Some people say that if you improve risk prediction you can assume you’ll improve patient outcomes, but it’s not so clear. All that prediction does is give the physician different information and the patient a different message. But those two things have to be potent enough to change what happens next. If you’re going to come out with a recommendation that a test should be done for everybody, it’s important to be confident of better patient outcomes."
The guideline was developed in collaboration with the American Society of Echocardiography, American Society of Nuclear Cardiology, Society of Atherosclerosis Imaging and Prevention, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, and Society for Cardiovascular Magnetic Resonance.
It includes the following recommendations for cardiovascular risk assessment in people without symptoms of heart disease:
Tests that should be performed in all adults for cardiovascular risk assessment
- Global risk scoring, taking into account such factors as cholesterol level, blood pressure, age, sex, diabetes and smoking
- Family history
Tests that are reasonable or may be considered in appropriate adults for cardiovascular risk assessment
- C-reactive protein, in intermediate-risk men age 50 and younger and women age 60 and younger, for cardiac risk assessment, plus a selected group of older people, for determining whether statin therapy is warranted
- Coronary artery calcium scoring, in people with diabetes age 40 and older, in intermediate-risk people and, possibly, those at low-to-intermediate risk
- Resting electrocardiogram (ECG), especially in people with high blood pressure or diabetes
- Ankle-brachial index, in intermediate-risk people, to test for atherosclerosis in the arteries of the legs
- Carotid intima-media thickness, in intermediate-risk people, to test for atherosclerosis in the arteries supplying blood to the brain
- Microalbuminuria, in intermediate-risk people or those with high blood pressure or diabetes, to test for early signs of kidney damage
- Conventional echocardiography, in people with high blood pressure, to check for thickening of the heart muscle
- Nuclear stress testing, in people with diabetes or a strong family history of heart disease, when previous tests suggest a high risk for heart disease
- Exercise ECG stress test, in intermediate-risk people, for example, before starting a vigorous exercise program
- Hemoglobin A1c, in people with or without diabetes, to gauge average blood sugar levels over time
- Lipoprotein-associated phospholipase A2, in intermediate-risk people
Tests that have no benefit in people without symptoms of heart disease
- Genetic testing
- So-called "advanced" lipid testing (e.g., apolipoproteins, particle size and density)
- Natriuretic peptide levels
- Coronary computed tomography angiography
- Magnetic resonance imaging for detection of vascular plaque
- Stress echocardiography
- Flow-mediated dilation
- Measures of arterial stiffness
The guideline also highlights the importance of assessing cardiovascular risk in all women, despite a lack of symptoms, using a global risk score and family history.
"Knowing whether a person is at low, intermediate or high risk helps a physician tailor therapy for that specific person," Dr. Greenland said. "There are a lot of tests out there and a lot of claims that these tests are valuable for risk assessment. This guideline puts it all in perspective."###
The American College of Cardiology is transforming cardiovascular care and improving heart health through continuous quality improvement, patient-centered care, payment innovation and professionalism. The College is a 39,000-member nonprofit medical society comprised of physicians, surgeons, nurses, physician assistants, pharmacists and practice managers, and bestows credentials upon cardiovascular specialists who meet its stringent qualifications. The College is a leader in the formulation of health policy, standards and guidelines, and is a staunch supporter of cardiovascular research. The ACC provides professional education and operates national registries for the measurement and improvement of quality care. More information about the association is available at http://www.cardiosource.org/ACC.
The American Heart Association, founded in 1924, is the nation’s oldest and largest voluntary health organization dedicated to building healthier lives, free of heart disease and stroke. To help prevent, treat and defeat these diseases — America’s No. 1 and No. 3 killers — we fund cutting-edge research, conduct lifesaving public and professional educational programs, and advocate to protect public health. To learn more or join us in helping all Americans, call 1-800-AHA-USA1 or visit www.heart.org.