Heart Disease Detection Goes High Tech
Experts review the latest techniques that reveal whether you have heart disease.
Although there is no doubt that the images with the improved CT scanners are very sophisticated, there is still controversy about the significance of calcium measurements in predicting heart disease.
"The CT scan is good, but it is not as specific for heart disease because people sometimes have calcium in blood vessels and no heart disease or vice versa," says cardiologist Gerald Fletcher, MD, of the Mayo Clinic in Jacksonville, Fla. Fletcher is a spokesman for the American Heart Association.
Because of this controversy regarding calcification scores, most insurance companies do not cover the heart CT scan as a screening test. But Flectcher says "the horse is out of the barn and people are paying out of pocket for it, and it has value as a screening technique when taken with precautions."
Richard D. White, MD, the clinical director of the Center for Integrated Non-Invasive Cardiovascular Imaging at the Cleveland Clinic, also urges caution with the use of cardiac CT scans. Cholesterol screens, stress tests, and other traditional risk stratification methods "are still the backbone of understanding the propensity of a patient to develop coronary artery disease," White says. "It would be detrimental if we got so enamored with imaging that we put them completely on the back burner."
White says the CT scan is best used when doctors have a significant concern about a risk for coronary artery disease in patients who are clearly not in need of a catheterization. "A swing vote from cardiac CT would help to decide whether to commit a patient to more testing or therapy" he says.
Another 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.
Fletcher cautions that while the new tests hold tremendous promise, they should not replace the traditional screening tests. "We know that old-fashioned cholesterol and blood pressure are important and the American public is still not properly controlling these basic things to prevent CVD," he says.
"There is no easy way," Fletcher says. "If you have high blood pressure and cholesterol and smoke or are overweight and sedentary, you need to address these risk factors before turning to new technologies," he says. "Start with the basic things and then look for your calcium score or CRP."