Experts review the latest techniques that reveal whether you have heart diseaseWhen former President Bill Clinton was diagnosed with heart disease and underwent a quadruple bypass operation to clear his blocked heart arteries in 2004, some Americans panicked and opted to undergo all sorts of tests to find out if they, too, had heart disease.
This hysteria -- and call to arms -- has been dubbed the "Bill Clinton Effect." More than two years after he underwent surgery, cardiologists now have even better high-tech tests enabling them to diagnose heart disease earlier -- with pinpoint precision. And more tests are being investigated.
"Ten to 15 years ago, industry and academia alike identified cardiovascular disease [CVD] as a disease to be tackled," says Stanley l. Hazen, MD, PhD. Hazen is section head of preventive cardiology and cardiac rehabilitation at The Cleveland Clinic in Ohio. "The boon of this research has yet to be materialized, but there are an extensive number of compounds and screening methods in the pike that look promising and attractive."
From blood tests to advances in imaging, here are a few highlights in heart disease detection.
Blood MarkersWhen you ask your doctor if you have heart disease, he assesses the likelihood based on risk factors. Some key risk factors are age, smoking, diabetes, being male, high blood pressure, and cholesterol. But studies have shown that almost half of the people who suffer coronary events have only two risk factors: being male and over 65. So it is very exciting when new tests come along that can help identify people before they have an event such as a heart attack.
In terms of blood markers, Hazen says that "the mainstay for assessing heart disease risk is low density lipoprotein ['bad'] cholesterol testing". But while we know that LDL plays a major role in determining heart disease, the relationship between severity and the timing of the disease is "incredibly poor. There is much room for improvement," says Hazen.
Checking for C-Reactive ProteinIn terms of blood-based screening tests, doctors are increasingly looking at levels of C-reactive protein (CRP), which is an inflammatory marker found in the blood. Several studies have shown that increased concentrations of CRP appear to be associated with increased risk for coronary heart disease, sudden death, and peripheral arterial disease. Inflammation is increasingly being viewed as a major risk factor for heart disease.
"This test is recommended by the American Heart Association and the federal Centers for Disease Control and Prevention," Hazen says. "If it's used as a routine screen in intermediate-risk subjects, it's an even stronger predictor of cardiovascular disease risk than LDL," he tells WebMD. While CRP levels are not specific to the heart, "in terms of risk prediction, it's equal to or better than cholesterol," he says. "More and more we will be seeing an increase in the use of CRP as an adjunct to risk stratification."
CT ScanningAnd these are some of the reasons that there is so much enthusiasm for the 64-slice computerized tomography (CT) scan. With this test, doctors can determine if there is calcium buildup in the heart arteries. While older multislice CT scans only allowed visualization of smaller parts of the heart, the 64-slice CT lets doctors visualize more. And computer processing yields a three-dimensional image of the arteries. This procedure eliminates the risk and discomfort associated with traditional angiograms, but there are the usual risks associated with exposure to X-radiation.
Magnetic ImagingAnother test for which both White and Fletcher see a bigger role in the future is magnetic resonance imaging (MRI) of the heart. According to Fletcher, MRI is more accurate than CT scanning. Although MRI is more difficult to perform and more expensive than CT scanning, he predicts that it will have an even bigger role in the future in detecting heart disease.
Other tests available to doctors include intravascular ultrasound (IVUS), a catheter-based technique, which provides real-time, high-resolution images of the heart and its arteries. "The images are in four distinct colors to tell what kind of plaque is there," Diethrich says. "We think that it is going to be very important because plaques differ a great deal. Some cause trouble and other plaques do not."
IVUS "is very good and accurate," says Fletcher. He also envisions a growing role for magnetic resonance angiogram (MRA). MRA is a noninvasive imaging test that uses a powerful magnet and radio waves to provide detailed images of the coronary arteries in less than one hour. "It's less invasive than catheterization," he tells WebMD.