Spotlight On: Screening for Heart Attack and Stroke

Can noninvasive screening help determine risk for heart attack and stroke?

More than 1 million Americans have a heart attack each year, and about 515,000 die annually from heart attacks, according to the National Heart, Lung, and Blood Institute. Meanwhile, about 700,000 Americans have a stroke, and about 150,000 people die from stroke each year.

One way to help identify people who may be at higher risk for stroke and heart attack is a noninvasive screening called a carotid intimal medial thickness (CIMT) ultrasound, which identifies whether patients have hardening of their arteries, known as atherosclerosis. Atherosclerosis is a key risk factor for both heart attack and stroke. More than 99 percent of heart attacks are caused by atherosclerosis, and atherosclerosis is one of three key risk factors for stroke. It's important to find atherosclerosis before a heart attack occurs, because doctors have treatments that can reduce your risk of a heart attack or sudden death.

To learn more about the "mammogram of the vascular system," Club Red talked with Chris Rembold, M.D., a Professor of Internal Medicine at the University of Virginia Health System who has researched the effectiveness of CIMT ultrasounds.

What does CIMT measure?

CIMT measures how much atherosclerosis (wall thickening and plaque) is present in the wall of the carotid artery. The carotid arteries are the arteries that feed your brain and face with blood. Ideally, we would like to measure atherosclerosis in the coronary arteries that supply your heart with blood, but the coronary arteries are hard to see with ultrasound because the ribs and lungs are in the way. Fortunately, the atherosclerosis (artery wall thickness and plaque) in the carotid arteries predicts who will have both heart attacks and strokes.

There is data from several large research studies showing that carotid thickness and carotid plaque predict heart attack and stroke quite well. We studied more than 700 people in Virginia and found that CIMT predicted who was more likely to have a heart attack, stroke or need to have an artery opened. From the CIMT results, we can say if your risk for a heart attack or stroke is less than, equal or greater than the average person your age.

Why are CIMT ultrasounds better than some other screening tests at predicting major cardiovascular problems such as heart attack and stroke?

Many cardiology tests answer a different question than a CIMT ultrasound. For example, cardiac catheterizations, stress tests and CT angiograms try to find out if there are blocked coronary arteries that cause chest discomfort that occurs with exercise (we call this "stable" angina). While these tests are good for finding blockages, they are not good in finding out whether there is atherosclerosis (thickening and plaque) in the walls of the artery. It is the atherosclerosis in the walls of the artery that causes most heart attacks. Therefore, it is important to find out how much atherosclerosis there is to find out who has a higher risk of a heart attack and sudden death.

How is CIMT measured? How long does it take?

CIMT is measured with an ultrasound machine in about 30 minutes. There is no discomfort, radiation or side effects for patients.

What groups of people might benefit from a CIMT ultrasound?

CIMT is a good test for:

• People who don't know if they have coronary or other artery disease but who have risk factors, including:
  • People whose cholesterol levels are borderline for being a risk factor for heart disease;
  • People with healthy cholesterol levels and a family history of heart disease; and
  • People with unhealthy cholesterol levels but no family history of heart disease.
• People who have had a previous heart attack.
• People who are seeking to determine if their cholesterol-lowering treatment is effective and necessary.
• People who wish to follow how well their cholesterol-lowering treatment is working. This group of patients may want a CIMT ultrasound every five years.

Where can I have a CIMT ultrasound performed?

Patients in Central Virginia can have a CIMT ultrasound performed by having their doctor schedule one at UVA's echocardiography lab by calling 434-924-2200. If you have questions about the cost of the procedure, since it if often not covered by insurance, please call 434.243.RATE.