The Best Screening Tests for People Without Symptoms of Heart Disease
February 1, 2012
By now, everyone is familiar with the cholesterol and blood pressure measurements that doctors use to gauge heart risks. But a number of newer screening methods -- from blood tests to noninvasive imaging techniques -- are also available to spot heart trouble ahead. Here's a breakdown of the traditional ways doctors predict your likelihood of heart problems and which additional tests you might -- or might not -- want to consider.
Studies suggest that some of the newer screening tests can detect "silent" atherosclerosis and predict heart attack risk in people with no symptoms of coronary heart disease such as chest pain and shortness of breath.
This is important because, too often, people with coronary heart disease have no indication of it until they suffer a heart attack or die suddenly of cardiac arrest. But with a constant stream of news reports on various new "markers" of coronary heart disease risk, it's easy to get confused about which tests you should consider. In fact, in many cases, even experts disagree over the appropriate use of newer coronary heart disease screening methods.
Traditional Risk Assessment -- For years, doctors have used a measure called the Framingham risk score (FRS) to gauge adults' risks of having a heart attack over the next 10 years. The score, which depends on your age, blood pressure, cholesterol levels, and history of smoking, categorizes you as being low risk (less than a 10% chance of having a heart attack in the next 10 years), intermediate risk (10–20% chance) or high risk (greater than 20% chance). An important exception: People with diabetes or coronary heart disease are already considered at high risk regardless of other risk factors.
The FRS is a time-honored predictor of heart attack risk, but there is growing evidence of its limitations, particularly for women, whose risk is often underestimated. A recent Hopkins study found that of more than 2,400 women ages 45 and up who were free of heart disease symptoms, one third had signs of atherosclerosis on coronary calcium scans. But the FRS deemed nearly all of them at low risk for a heart attack, which means they probably would not be started on a statin or aspirin therapy to help protect their hearts.
The limitations of traditional risk factor assessment, coupled with the fact that coronary heart disease is often silent, has researchers looking for ways to improve screening. Here are a few of them.
- CRP. Blood C-reactive protein (CRP) is one of the newer coronary heart disease screening tests. It is a marker of inflammation in the arteries and is thought to play a role in the accumulation of plaques in the coronary arteries. A number of studies have found CRP levels to predict a person's risk of heart attack. A study in the Journal of the American Medical Association concluded that adding a CRP test to the traditional FRS measure may improve heart attack prediction for women.
Besides CRP, family history of heart disease (having a parent who had a heart attack before age 60) also helped calculate a woman's odds of heart trouble. In the study, which included nearly 25,000 women ages 45 and older, adding CRP and family history using a measure called the Reynolds Risk score changed the outlook for nearly half of them; some women were found to have a higher-than-thought heart attack risk, while others were actually at lower risk.
- Coronary calcium scans. A coronary calcium scan is another potential coronary heart disease screening tool, but its use has been controversial because of uncertainty about its value. In late 2006, however, the American Heart Association (AHA) released long-awaited guidelines on the test, deeming it a reasonable option for symptom-free people at intermediate risk for coronary heart disease.
The test uses high-speed x-ray technology to find calcium deposits in the coronary arteries. Because calcium is frequently a component of the plaques that build up in the arteries, a calcium scan can indicate whether you have atherosclerosis, and how severe it is.
- Exercise stress testing. For individuals with possible symptoms of coronary heart disease, such as chest pain, an exercise stress test is often the initial diagnostic test. But the test has also been proposed as a way to screen people who are symptom free but at intermediate risk for coronary heart disease.
- Homocysteine. This blood amino acid is linked to a higher coronary heart disease risk. Researchers suspect high homocysteine levels may contribute to coronary heart disease by damaging the lining of the arteries and promoting blood clots. For now, experts advise against widespread screening of homocysteine levels, because it's unclear whether the information adds anything to standard risk factor measurements. In addition, studies evaluating treatments that lower homocysteine (such as supplements of folic acid and other B vitamins) have demonstrated no improvement in coronary heart disease risk.
Bottom line: It's important to remember that even experts disagree over the value of adding these newer screening tests to traditional risk factor assessment, and there's no one-size-fits-all recommendation for any of them. For instance, if you're already taking a statin or a daily aspirin, a positive result on one of these tests could prompt your doctor to increase the intensity of measures to lower heart attack risk. But there is also a chance that the test will provide no additional information, simply confirming that you are already taking the appropriate steps.
Another scenario: You are not taking a statin or aspirin but are concerned because your cholesterol isn't optimal and your father had a heart attack at age 45. Then it might be worthwhile to have one of these other screening tests to help clarify your risk. The decision will ultimately come down to a thorough discussion of your coronary heart disease risk with your doctor.
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