Coronary Artery Disease Might Lurk Unknown

Coronary artery disease (CAD) is the most common type of heart disease and the leading cause of death in the US for both men and women. About 13 million Americans have CAD and each year more than half a million die from it. Unfortunately, you might not even know you have CAD until the disease has progressed to a dangerous stage.

What is CAD? The coronary arteries are vessels that carry blood and oxygen to the heart muscle. Plaque deposits, made up of fat, cholesterol, calcium and other substances from the blood build up in the arteries, especially if you have certain risk factors. "Plaque forms in the arteries over many years in a process called atherosclerosis. When the arteries become filled with plaque and fibrous tissue, they become narrowed and less elastic," according to David S. Marks, MD, Associate Professor of Medicine at the Medical College of Wisconsin and Director of the Cardiac Catheterization Lab for Froedtert & The Medical College of Wisconsin. This is the origin of the phrase "hardening of the arteries."

Symptoms of CAD
As plaque narrows the arteries, blood flow to the heart is reduced, eventually causing chest pain or angina. "If a blood clot forms, it can suddenly cut off blood flow in the artery and cause a heart attack," Dr. Marks said. Angina and shortness of breath are often the first signs of CAD. In fact, many people don't know they have CAD until they have a heart attack. This is why it makes sense to know your risk factors for the disease - and to maintain a healthy lifestyle.

Risk Factors Some factors can make it more likely that you will develop CAD in your lifetime. These risk factors may include some things you cannot control, including:

• Family history of early heart disease: Heart disease diagnosed before age 55 in father or brother
• Heart disease diagnosed before age 65 in mother or sister.
• Gender: In men, risk increases after age 45. Women tend to get heart disease later in life (usually after age 55) because female hormones seem to offer protection.

Risk factors that you can do something about include:

• High blood cholesterol
• High blood pressure (hypertension)
• Diabetes
• Smoking
• High-fat diet
• Overweight
• Sedentary lifestyle (lack of exercise)
• High stress

If you have several of these risk factors, follow your doctor's treatment orders. If you have any signs of heart disease such as chest pain, see your physician right away. If you are at high risk for CAD, your healthcare provider may suggest that you be tested even if you have no symptoms.

Diagnosing CAD
There are some tests that physicians commonly use to help them diagnose CAD. If you go to see your doctor with symptoms that may indicate you have CAD, the doctor will likely schedule you for one or more tests, such as:

• Electrocardiogram (EKG or ECG). This test records the heart's electrical activity and may reveal problems such as an abnormal heartbeat.
• Echocardiogram. This test examines the heart function using sound waves.
• Stress tests. In this test, your heart, breathing, and blood pressure are monitored while you exercise on a treadmill. Other types of stress tests may include the use of a radioactive isotope and monitoring devices that can trace the blood flow through the heart.

Depending upon the severity of your symptoms, your physician might also schedule coronary angiography or arteriography. This is a computerized x-ray of the coronary arteries. A catheter (a thin plastic tube) is inserted into an artery in the groin or arm and threaded into a coronary artery. A fluid is injected and x-rays can reveal blockages in the arteries.

Current research is evaluating the use of a special CT scanner with multiple detectors to replace cardiac catheterization. This procedure uses advanced CT technology and computer reconstructive methods to view the blood flow in the arteries without having to inject through catheters in the arteries. This technique, particularly because it is less invasive, has led to great enthusiasm. Current research is attempting to establish the accuracy of this test.

C-Reactive Protein
A simple blood test for something called "C-reactive protein" may also be an indicator of heart disease. "C-Reactive protein is a protein found in the blood. It is a marker for inflammation in the body," Dr. Marks said. Inflammation is a normal response to many physical states including injury and infection, but studies have shown that CRP levels seem to be correlated with levels of cardiac risk.

"The CRP test can be helpful if patients don't have another autoimmune disorder such as arthritis. An elevated CRP is related to increased risk for heart attack, but it also may be a helpful measure that indicates a patient's response to therapy," Dr. Marks said. "Currently, the test is not commonly done, but its use is increasing."

Treating CAD
Fortunately, physicians can treat CAD with recommended lifestyle change, medicine and surgical procedures. Medicine can be the first step in treating heart disease, depending upon how severe the disease has become. Some medicines can lower blood pressure and heart rate or lower cholesterol levels in the blood. Other medicines can act as blood thinners, preventing blood clots. Aspirin also helps to lower the risk of a heart attack for those who have already had one, helping to keep the arteries open. Because aspirin can cause stomach bleeding, the Food and Drug Administration has not approved aspirin to prevent heart attacks in healthy people. Ask your physician if it is right for you.

If tests reveal that you have a blocked artery, your physician might want you to have a surgical procedure called angioplasty. A catheter is inserted into the groin or wrist and threaded into the narrowed artery. The catheter has a tiny balloon at its tip that is repeatedly inflated and deflated to open and stretch the artery, improving blood flow. The tube is removed and a stent (small mesh tube) is put in to keep an artery open.

Sometimes, CAD is severe enough to require coronary artery bypass surgery, an operation to bring blood flow to the heart. In this procedure, a blood vessel is taken from another part of your body and attached above and below the narrowed part of the artery - bypassing the blockage. Bypass surgery can improve chest pain and lower the risk of a heart attack, but a bypass artery can also become blocked.

"None of these procedures is a cure for CAD and, although they are extremely effective in restoring blood flow to areas of the heart, there is a chance that the blockage could return or new blockages form," Dr. Marks said.

Preventing CAD
The more risk factors you have, the greater your chance for CAD. You cannot control your age and sex, but you have the power to control some of the other risk factors. "If you are a smoker, quit smoking. Keep your blood pressure and blood cholesterol down. Eat a healthy diet, avoiding foods high in saturated fat, get regular exercise, and keep your weight under control," Dr. Marks said.

JoAnn Petaschnick
HealthLink Contributing Writer

This article contains information from the National Institutes of Health.

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.