Doctors may suggest a screening test to make sure cardiovascular health is in top shape. But if a person lacks symptoms -- like chest pain or shortness of breath -- they might want to hit pause for a second and look closer at the costs and benefits.

The fact is, there is no good evidence that any of the common tests are that helpful if a person is symptom-free.

"If you do a test like a stress test in someone who doesn't have any symptoms, then you are more likely to get a false-positive test than a true positive," said Dr. Malissa Wood, a spokesperson for the American Heart Association.

Such false alarms trigger more unnecessary tests, which often carry significant risks.

"We really want to go based on symptoms," Wood said.

The government-backed U.S. Preventive Services Task Force also advises against routine screening for heart disease for people at low risk.

Even for those at higher risk -- like smokers, diabetics and the obese -- there is insufficient evidence to support routine screening, according to the USPSTF, which bases all of its advice on rigorous science.

Still, groups with ties to drug and heart device makers often recommend the tests routinely, and several companies promote them, to the chagrin of experts in the field.

"There are no 'heart tests' that any asymptomatic man or woman should get," said Dr. Patrick O'Malley, an internist at the Uniformed Services University of the Health Sciences in Bethesda, Maryland. "There are many that are done which they shouldn't get."

Here's a brief guide to the common heart tests:

TEST 1: ECG (EKG)

What is it? An electrocardiogram, or ECG, is simply a readout of your heart's electrical activity recorded by electrodes placed on the chest. It can pick up abnormalities that might, or might not, signal heart disease in the making.

Does it work? ECGs are used to study irregular heart rhythms, heart attacks and other problems. They're also used before some types of surgery, but no trials have looked at whether ECGs help stave off disease in people without symptoms.

What's the harm? An ECG typically costs about $50. Because it's not invasive, the test itself is safe. What someone should worry about is what happens if the results look abnormal. A patient might end up with another test that carries more risks, like a CT scan or a coronary angiogram, during which a catheter is threaded into the heart.

TEST 2: CAROTID ULTRASOUND

What is it? A carotid ultrasound allows doctors to see if the arteries in the neck that supply blood to the brain, called the carotids, are clogged by cholesterol buildups, or plaque. That is considered a risk factor for stroke.

Does it work? This test is used to check the blood flow to the brain. There is no evidence that carotid plaque screening, which is becoming increasingly popular, saves lives. The USPSTF says the harm of routine scans outweighs the benefits.

What's the harm? An ultrasound of the carotids costs between $200 and $300. Routine scans produce more false alarms than "true positives," and may lead to invasive imaging or carotid surgery or stenting. Between one and three percent of patients who get carotid surgery die due to the procedure, and even more suffer strokes from it.

TEST 3: ECHOCARDIOGRAM

What is it? An echocardiogram is a moving ultrasound picture of the heart. It allows the doctor to test how well the heart pumps out blood and whether it has structural problems.

Does it work? While the test might help doctors diagnose conditions like heart failure and atrial fibrillation, it hasn't been proven to help people without symptoms. One recent study found screening for heart disease with echocardiography and other tests didn't change what drugs doctors prescribed, nor people's diet and exercise habits or whether they smoked.

What's the harm? An echocardiogram costs between $200 and $300. Ultrasound scans are generally safe, but can trigger false alarms and may lead to more-invasive tests and treatments later.

TEST 4: STRESS TEST

What is it? To spot signs of pumping problems, a doctor will stress the heart by putting a person on a treadmill or stationary bike while doing an echocardiogram or an ECG. In a nuclear stress test, radioactive dye is injected into the bloodstream to create a better picture.

Does it work? Stress tests can help diagnose heart problems but haven't been shown to be helpful screening tools. Some studies have shown they may miss signs of heart disease.

What's the harm? A stress test may cost anywhere from a few hundred dollars to $1,000. It carries the usual risks of exercise, but largely for people with heart problems -- including very rare cases of heart attack. Some tests will result in false alarms, meaning further procedures with possible complications will be done unnecessarily.

TEST 5: CARDIAC CT SCAN

What is it? CT (computed tomography) scans use high-dose x-rays to get a detailed picture of the heart. In a coronary calcium scan, the doctor looks for calcium deposits in the heart's arteries, which have been tied to an increased risk of heart disease. Patients may also have a dye injected to make it easier to spot blockages.

Does it work? CT scans may help separate women at moderate risk of heart disease into those who would benefit from aggressive treatment and those who wouldn't. But for people without symptoms, CT scans still haven't proved more valuable than medical advice based on well-known risk factors like diabetes and obesity.

What's the harm? The radiation from CT scans, which may cost several hundred dollars, may increase one's cancer risk slightly. When dye is used, about one in 10 people develop kidney damage and some may get thyroid problems, too. False alarms may lead to invasive tests, which carry more risks.

HEALTHY LIVING, NOT TESTS

Experts say the best way to prevent heart disease has little to do with technology and everything to do with lifestyle.

"Tests do not prevent heart disease," said Dr. Rita Redberg, a cardiologist at the University of California, San Francisco. "To prevent heart disease, women (and men) should eat healthy diets with lots of fruits and vegetables, get regular physical activity and not smoke."

The American Heart Association also recommends keeping your blood pressure and cholesterol levels under control, although the USPSTF says there is too little evidence to recommend cholesterol tests when women don't have other heart risks.

(Editing By Peter Bohan)

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