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Tests for hidden heart disease

Electrocardiograms, which monitor the heart’s electrical patterns, don’t reliably reveal the risk of having a heart attack.

Unless you have symptoms of a heart problem, taking a cautionary look under the hood is unlikely to help—and could even be harmful.

As men age, heart disease becomes a greater concern. Indeed, heart problems can develop seven to 10 years earlier in men than in women. Half of men who die suddenly from heart disease had no warning signs. Men worry, understandably, that they harbor a “heart attack waiting to happen” and wonder if high-tech tests can offer important information—or at least reassurance.

However, experts say that checking an otherwise healthy man for hidden heart disease is usually fruitless. “It is just throwing money and time down the drain, and it doesn’t achieve its intended purpose,” says Dr. Sekar Kathiresan, director of preventive cardiology at Harvard-affiliated Massachusetts General Hospital.

Indeed, an advisory report released in March 2015 by the American College of Physicians urged doctors not to use electrocardiograms (ECGs) and exercise stress tests to check men with no symptoms of heart disease. Other major medical organizations have taken similar positions.

Here is what you need to know to have an informed discussion with your doctor and make a smart cardiac screening decision.

Electrocardiogram

In an ECG, small adhesive-backed electrodes are placed on the chest to record the electrical activity in your heart. Perhaps because ECGs are relatively inexpensive, some primary care physicians still include them in routine physicals for men middle-aged and older.

What it can tell you. An ECG may reveal abnormalities in heart rhythm, damage from a previous heart attack, or an enlarged heart. If fatty deposits have narrowed one or more of your coronary arteries enough to interfere with the flow of blood to the heart, an ECG can detect that.

Exercise stress test

In an exercise stress test, the goal is to see how your heart performs during physical activity—when the heart muscle demands more oxygen-rich blood. The test is usually performed with you exercising on a treadmill or exercise bicycle while your heart rate, blood pressure, and heart function are monitored.

Stress testing with ECG is the most common approach. One variation, a nuclear stress test, takes images to show how much blood is percolating into the heart muscle. Another variation—stress echocardio-graphy—checks for how effectively the heart’s pumping chambers and valves operate.

What it can tell you. Whichever type of stress test you undergo, the goal is similar. You want to find out if the heart functions normally when you put extra demands on it. If one or more coronary arteries have significant blockages, it could cause chest pain or other symptoms, an abnormal heart rate or blood pressure, or other potentially harmful changes in heart function.

If the stress test result is abnormal, don’t panic: you don’t necessarily have heart disease. Most of the worrisome findings turn out to be false alarms—up to 75% of them, in some studies. But to find out, you will need more tests, and those carry additional medical risk and costs, not to mention anxiety.

Uncertain benefits

The biggest shortcoming of screening for heart disease with an ECG or exercise stress test is that it doesn’t tell you what most men really want to know: whether you will have a heart attack. If nothing shows up out of the ordinary on the test, it just indicates that you don’t have significant narrowing of the coronary arteries.

That’s good news, but it doesn’t exclude the presence of “silent” deposits that could suddenly rupture in the future. “Most heart attacks happen not because of severe blockages, but because blockages that you would never pick up on a stress test break open and trigger a clot,” Dr. Kathiresan says.

Current guidelines recommend that doctors use the traditional cardiovascular risk factors—not ECGs and stress tests—to estimate the risk of heart disease in men without symptoms and recommend the next steps based on that. The key factors are age, body mass index, family history, blood pressure, cholesterol levels, and whether you smoke or have diabetes. These provide a more accurate assessment of cardiac risk than screening tests do.

If the risk is higher than you want it to be, adopting a healthier lifestyle and taking appropriate preventive medications can help lower the risk. “Only two types of medication are proved to reduce risk of first heart attack—aspirin and statins,” Dr. Kathiresan says. “And if you have high blood pressure, lowering it has the same effect.”

Coronary artery calcium (CAC) scan results

This CT scan shows extensive calcified plaque (see arrow) in the heart’s arteries.

Image: National Institutes of Health

Coronary artery calcium score: The tiebreaker test

Guidelines say anyone with a 10-year heart disease risk of 7.5% or higher should consider taking a statin drug to lower that risk. But if you are close to that threshold and are not sure you want to commit to taking a daily medication for life, Dr. Kathiresan says, a procedure called a coronary artery calcium (CAC) scan could provide a “tiebreaker” to help you make the decision. This test uses a brief, low-dose computed tomography (CT) scan to locate and measure calcium-rich deposits of fatty plaque in the coronary arteries.

Measurements of the density and size of the specks are used to create a numerical score that reflects the extent of the deposits. An elevated calcium score could, for instance, raise your heart attack risk estimate from low to moderate. Based on that, your doctor may advise you to take a statin or a daily low-dose aspirin, if you are not already doing so.

As with any kind of testing, calcium scanning comes with drawbacks:

  • Unproven benefit. No major clinical trial has demonstrated that having a CAC scan ultimately leads to changes in your care that prevent heart attacks.

  • More cardiac testing. A high score could lead to additional, more invasive testing—like angiography, which requires threading a catheter up to your coronary arteries to inject dye and having another x-ray to look for blockages.

  • Incidental findings. Calcium scans often reveal spots in your lungs, kidneys, or other places that would then need to be investigated with more tests.

  • Out-of-pocket costs. Depending on your health insurance coverage, you might have to pay the entire cost of the CAC scan, which runs from around $100 to several hundred dollars.

Posted by: Dr.Health

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