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Keep the Beat
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Understanding heart-health screenings and diagnostic tests
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By Stacey Colino
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REMEDY Spring 2009
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Lifelong heart health depends on making smart lifestyle choices such as not smoking, getting regular exercise, eating a nutritious, balanced diet and working with your doctor to identify developing cardiovascular problems. But it is not easy to know which tests you should be taking or how to decipher what their results mean for you.
Generally, heart-health tests are used for either screening or diagnosis. What’s best for you will depend on your age, symptoms, family history and other personal factors.
“There is no single test to diagnose heart disease—and the testing one person undergoes may be significantly different from what is best for someone else,” says Nieca Goldberg, M.D., associate professor of medicine at NYU Langone Medical Center in New York and author of Dr. Nieca Goldberg’s Complete Guide to Women’s Health.
To reduce your heart disease risks, you need to know your personal risk factors—that’s one instance when screening tests are useful. They can also help you gauge whether any lifestyle changes you’ve made are reducing your risks sufficiently. Here are the screening tests adults should have:
• Blood pressure Your doctor should check your blood pressure annually. If it’s high (140/90 or higher), it should be monitored more often, and you should take steps to lower it by losing excess weight, exercising regularly, sticking with a low-sodium, heart-healthy diet and perhaps taking anti-hypertension medication. The goal: to get it under 120/80.
• Fasting lipid profile Starting at age 20, you should have a fasting blood lipid test, which measures total cholesterol, LDL (bad) cholesterol, HDL (good) cholesterol and triglyceride levels. (Triglycerides, a type of fat in the blood, are an important measure of your heart health.) This test should be repeated every five years if results are in the normal range, more often if they are not.
Normal results The recommendations are: total cholesterol under 200, LDL under 100 and HDL of at least 50 for women and at least 40 for men; HDL levels of 60 and higher are protective.
Abnormal results If the results are abnormal, following a low-fat, heart-healthy diet, exercising regularly and losing excess weight can help. In addition to lifestyle modifications, you may be prescribed a cholesterol-lowering medication; if so, your lipid levels should be monitored at least every six months, says Kansas City, MO, cardiologist Tracy Stevens, M.D.
• Fasting blood glucose test This will indicate if your blood sugar levels are normal (under 100 when fasting or in the morning) or if you have diabetes (126 or higher). “If you’re lean and fit, and you don’t have a family history of diabetes, you can wait to have this until your forties,” says Robert O. Bonow, M.D., chief of cardiology at Chicago’s Northwestern Memorial Hospital. “If you’re overweight or have a family history of diabetes, you should have your blood sugar level tested when you are in your twenties.”
Abnormal results If your blood sugar is borderline high (in the prediabetes range), shedding excess pounds, exercising regularly and consuming a diet rich in fruits, vegetables, fiber, whole grains and low-fat dairy products can help you control your blood sugar. If you have type 1 diabetes, daily injections of insulin are mandated. For type 2 diabetes, oral medication or insulin may be warranted. In both cases, you’ll be advised to have regular hemoglobin A1C tests, which measure your average blood sugar levels over a period of three months.
• Specialized screenings If you have a strong family history of heart disease but your blood pressure, lipid and glucose levels are normal, your doctor may do additional blood tests. These will check your levels of some other blood factors that may indicate a risk for heart disease. These tests look for elevated levels of C-reactive protein (CRP), a marker of inflammation; Lp(a), a harmful type of cholesterol that’s similar in chemical structure to LDL; and homocysteine, an amino acid. Knowing that one or more of these factors is elevated can help doctors decide how to treat borderline-high cholesterol, for example. “If we’re on the fence about whether to put a person on a statin or to stick with diet and exercise as therapy, knowing that his CRP level is high might convince us to put him on a statin sooner,” says Dr. Bonow.
If you have symptoms such as chest pain or tightness; unexplained shortness of breath, sweating, nausea, vomiting, or severe fatigue; dizziness; or worrisome symptoms that come on with physical activity, it may be time for more extensive testing. People with diabetes or fatty blockages in the arteries of the legs may also benefit, Dr. Goldberg says.
• Electrocardiogram (EKG) Providing a graphic picture of the electrical impulses in the heart, an EKG, or ECG, can detect abnormal heart rhythms, decreased blood flow to the heart or a heart attack. Abnormal results or persistent chest discomfort may warrant further testing. A caveat: False negatives—a normal result even though there are underlying problems—sometimes occur.
• Echocardiogram This test, in which sound waves create images of how the heart muscle and valves are functioning, may be done if a baseline EKG is abnormal or you have a heart murmur or hypertension. “It’s an excellent, noninvasive way to assess valve problems and structural abnormalities in those with heart arrhythmias,” notes Dr. Goldberg. “Accuracy depends on the skill of the technician and the physician.”
Six questions from Tracy Stevens, M.D., a cardiologist and medical
director of the Saint Luke’s Muriel I. Kauffman Women’s Heart Center in
Kansas City, MO:
1. Why are you ordering this test for me?
2. What will it tell us?
3. How likely is it to be accurate in my case?
4. Are my results in the normal range?
5. If not, what do we need to do next?
6. Are there options for managing this with medication, or will we need to do something more invasive?
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A variety of new tests may improve the detection of heart disease,
often with fewer side effects. Ask your doctor about their availability
and potential usefulness for you. These cutting-edge tests include:
• computerized tomographic (CT) angiography that uses reduced doses of
X-rays with an angiogram to create detailed images of the blood vessels
in the body.
• a magnetic resonance angiogram(MRA) that uses magnetic fields and
radio waves to produce two- or three-dimensional images of blood
vessels.
• a positron emission tomography (PET) scan used in conjunction with a
chemical stress test to provide clearer images of the heart,
eliminating shadows.
• genetic tests for heart disease—especially helpful for those who have a family history of sudden cardiac death.
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• Stress test There are three forms of stress tests that are commonly used. In an exercise stress test, a person walks on a treadmill or pedals a stationary bike while an EKG or echocardiogram evaluates the heart’s response. With a nuclear stress test, a radioactive isotope travels into the heart and, when tracked by a scanning camera, provides a picture of how blood flows through the heart during exercise. A chemical stress test uses synthetic medications that mimic the effects of exercise. If the test indicates reduced blood flow to the heart, your doctor may recommend an angiogram.
• Coronary angiography With this invasive test, done in a hospital, a catheter (tube) is inserted into an artery in the groin, and dye is injected into the coronary arteries to highlight blockages in the heart’s blood vessels. (This information can also be gathered in an outpatient setting via a computerized tomography [CT] scan angiogram, which uses X-rays and shows a cross-sectional view of the insides of the body.) An angiogram may be recommended if your doctor suspects unstable angina (chest discomfort), if you’ve had an abnormal EKG or stress test or if you are having heart attack symptoms. It can also help pinpoint the location and amount of obstruction in a blood vessel.
• Ankle-brachial index (ABI) test Your doctor uses a special blood pressure cuff to compare the blood pressure ratio in your legs to the ratio in your arms. This screens for peripheral artery disease (PAD), a condition caused by plaque buildup in arteries outside the heart, such as those in the legs.
• Coronary artery calcium scoring This test uses a CT scan to evaluate calcium deposits in the heart’s arteries. Their presence can help doctors decide how aggressively to use medication to try to lower your cholesterol or to treat any other risk factors you might have.
Are you worried about a heart attack? While certain heart disease risk
factors (age, sex and genes) can’t be avoided, others, such as smoking,
obesity, high blood pressure and inactivity, are under your control.
When it comes to nutrition, picking the right mix of protein, carbs and
fat ensures that your system is getting what it needs. But how do you
choose wisely? “There are a lot of terms being tossed around out there:
phytochemicals, antioxidants, flavonoids and polyphenols,” says Beth
Thayer, R.D., spokesperson for the American Dietetic Association. “Each
fruit and vegetable has its own mix of these properties. That’s why
it’s important to eat a variety of them. It’s the same with grains:
Choose whole grains rather than processed or refined grains.”
Legumes such as beans are also heart boosters, Thayer adds. “They are a
great source of soluble fiber, which binds up cholesterol in your gut.”
They also provide folic acid. That’s key, because a deficiency can lead
to elevated homocysteine—a risk factor for heart disease. Aim for at
least 25 grams of total fiber and 400 micrograms of folic acid daily.
For protein, it’s beans and legumes again, along with oily fish such as
salmon, trout and herring, which are full of heart-healthy omega-3
fatty acids.
Add at least two 3-ounce servings of oily fish per week to your diet.
Reduce your intake of saturated fats and trans fats (vegetable
shortening, some margarines, crackers, cookies and snack foods). Both
can raise LDL (bad) cholesterol levels; trans fat also decreases HDL
(good) cholesterol levels. How much is too much? The American Heart
Association suggests that your saturated fat intake remain less than 7
percent and trans fat less than 1 percent of your daily calories.
—Nancy Christie |
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