T oday, more American women die from heart disease than from all cancers combined -- so it’s tempting to try to protect yourself by getting cardiac screening tests during your annual checkup.

However: For women who have no signs or symptoms of heart problems and who are not at high risk for heart disease, certain screening tests are a waste of time and money.

Reasons: They are unlikely to provide information that is useful -- and they even may be dangerous because they involve radiation.

Concern for women: The more radiation you receive over a lifetime, the higher your risk for cancer. Women are advised to get regular mammograms to screen for breast cancer. Because mammography uses X-rays, women’s radiation exposure already tends to be higher than men’s. That is why women must be especially wary of increasing their radiation exposure and consequent cancer risk with unnecessary cardiac testing.

Here’s what women need to know about heart disease screening tests...

TESTS TO AVOID

In certain circumstances, cardiac diagnostic tests are potentially lifesaving and well worth the risks involved. The four tests described below may indeed be necessary if you have any signs or symptoms of heart problems, such as chest pain, irregular heartbeat, shortness of breath, dizziness, fainting, or pain or swelling in the limbs.

These tests also may be appropriate if you have one or more factors that place you at high risk for heart disease -- such as high blood pressure, high cholesterol, high triglycerides (a type of blood fat), diabetes, obesity, high-fat diet, sedentary lifestyle, smoking habit or family history of heart disease.

However: If you do not have any signs, symptoms or risk factors, there’s no reason to get the four tests below. They can cost hundreds or thousands of dollars -- and health insurance typically does not pay for them for screening purposes. So if your doctor recommends testing, ask for a clear and detailed explanation of why each test is being ordered in your particular case.

Coronary artery calcium (CAC) scan. This checks for deposits of calcium that are associated with plaque in the coronary arteries. You lie on a table while a computed tomography (CT) scanner takes multiple X-rays from various angles and uses these to create a three-dimensional image. White spots suggest calcium deposits.

Problem: The National Cancer Institute reports that the average radiation exposure from having this test every five years would cause 62 additional cases of cancer per 100,000 women (and 42 additional cases per 100,000 men).

Also: CAC scans have not been shown to be effective at saving lives in people with no heart disease symptoms or significant risk factors.

CT angiogram. The goal is to detect blockages of fatty plaque in the blood vessels or chambers of the heart. A tiny tube is inserted into your arm, then dye is injected to make blood vessels visible by X-ray. You may be given beta-blocker medication to slow your heart during the procedure.

Problem: This test is less accurate in women than in men because women’s plaque tends to be more evenly distributed throughout the arteries.

Risks: There is radiation... the dye may cause an allergic reaction... or the beta-blocker may trigger asthma or slow the heart too much, leading to low blood pressure, fainting or (rarely) death.

Exercise electrocardiogram (ECG). This provides a graphic record of the heart’s electrical activity. Wires taped to your skin connect you to an ECG machine while you walk on a treadmill.

Problem: Because women’s heart vessels differ somewhat from men’s, an exercise ECG is less accurate at detecting large artery blockages in women. Though there is no radiation, the test is not worth the effort or expense for a patient without signs or symptoms of heart disease.

Cardiac ultrasound. Also called an echocardiogram, or echo, this uses sound waves to generate a picture of the heart. A conductive gel is spread over your chest, then a handheld transducer is moved over the area to produce sound waves.

Problem: Though this test is safe and it helps diagnose the cause of existing heart disease, it does not reliably identify heart problems before symptoms develop. For this reason, the cardiac ultrasound is not a good general screening tool.

TESTS WORTH DOING

Every adult woman should be assessed annually for heart health.

How: During your routine physical, your doctor should record your height, weight, waist circumference and blood pressure... order fasting blood tests for glucose, cholesterol and triglyceride levels... and discuss your diet, exercise habits, alcohol consumption, cigarette use and family history. Based on these factors, your doctor calculates your risk for heart disease, heart attack and stroke.

If this annual evaluation indicates that your risk for heart disease may be elevated, your doctor may consider doing the following safe, radiation-free tests to get a clearer picture of your heart health...

Resting ECG. This is an electrocardiogram taken while you lie quietly. It is able to identify atrial fibrillation, an irregular quivering of the heart muscle that increases stroke risk.

Insurance does pay if a physician orders this test for an approved indication. Unfortunately, many insurance companies now refuse to cover the test as part of a routine physical -- so ask your doctor if you should consider getting it anyway and paying out-of-pocket.

Cost: $75 to $400, depending on your location and provider.

Carotid intima-media thickness (C-IMT) measurement. The test uses ultrasound to measure the thickness of the arterial wall in the carotid artery in the neck, which is an indicator of plaque buildup. Repeating this test as directed by your physician may help detect changes in your cardiovascular health.

The test works as well for women as for men and can help your doctor determine whether you would benefit from taking a daily aspirin or statin drug.

Cost: $250 to $500, usually not covered by insurance. If you are at intermediate risk, your doctor may advise you to pay for this test if the results could help determine the best course of action.

High-sensitivity C-reactive protein test (hs-CRP). The regular CRP blood test measures levels of a protein linked to inflammation, which in turn is linked to heart disease. The high-sensitivity version more accurately reveals when the protein concentrations are only slightly elevated, so it is more useful in predicting a healthy person’s heart disease risk.

Among people whose hs-CRP levels are in the high end of the normal range, heart attack risk is one-and-a-half to four times higher than in people whose CRP is at the low end.

Cost: About $50, often covered by insurance.

Free self-assessment tool: To get an idea of your chances of developing heart disease within 10 years, check the online calculator from the National Heart, Lung and Blood Institute at http://hp2010.nhlbihin.net/atpiii/calculator.asp.