How is CAD Diagnosed?
Your doctor will diagnose coronary artery disease (CAD) based on your medical and family histories, your risk factors for CAD, a physical exam and the results from tests and procedures.
No single test can diagnose CAD. If your doctor thinks you have CAD, he or she may recommend one or more of the following tests.
An EKG is a simple, painless test that detects and records the heart's electrical activity. The test shows how fast the heart is beating and whether its rhythm is steady or irregular. An EKG also records the strength and timing of electrical signals as they pass through the heart. An EKG can show signs of heart damage due to CAD and signs of a previous or current heart attack.
During stress testing, you exercise to make your heart work hard and beat fast while heart tests are done. When your heart is working hard and beating fast, it needs more blood and oxygen. If you have CAD, your arteries can not supply enough oxygen-rich blood to meet your heart's needs.
A stress test can show possible signs and symptoms of CAD, such as:
- Abnormal changes in your heart rate or blood pressure
- Shortness of breath or chest pain
- Abnormal changes in your heart rhythm or your heart’s electrical activity
As part of some stress tests, pictures are taken of your heart while you exercise and while you rest. These imaging stress tests can show how well blood is flowing in your heart and how well your heart pumps blood when it beats.
If you can't exercise, you may be given medicine to raise your heart rate. If you can't exercise for as long as what is considered normal for someone your age, you may have CAD. However, other conditions such as lung disease, anemia or poor general fitness can also prevent you from exercising long enough.
Echocardiography (also known as echo) uses sound waves to create a moving picture of your heart. The picture shows the size and shape of your heart and how well your heart chambers and valves are working. Echo can also show areas of poor blood flow to the heart, areas of heart muscle that aren't contracting normally and previous injury to the heart muscle caused by poor blood flow.
A chest X-ray takes pictures of the organs and structures inside your chest, such as your heart, lungs and blood vessels.
A chest X-ray can reveal signs of heart failure, as well as lung disorders and other causes of symptoms not related to CAD.
Blood tests check the levels of certain fats, cholesterol, sugar and proteins in your blood. Abnormal levels might be a sign that you're at risk for CAD.
Electron-Beam Computed Tomography
Electron-beam computed tomography (EBCT) is a test that looks for specks of calcium, called calcifications, in the walls of the coronary arteries. Calcifications are an early sign of CAD. EBCT can show whether you're at increased risk for a heart attack or other heart problems before other signs and symptoms occur.
EBCT isn’t routinely used to diagnose CAD because its accuracy isn’t yet known.
Coronary Angiography and Cardiac Catheterization
Your doctor may recommend coronary angiography if other tests or factors show that you're likely to have CAD. This test uses dye and special X-rays to show the insides of your coronary arteries.
To get the dye into your coronary arteries, your doctor will use a procedure called cardiac catheterization. A thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh) or neck. The tube is threaded into your coronary arteries and the dye is released into your bloodstream.
Special X-rays are taken while the dye is flowing through your coronary arteries. The dye lets your doctor study the flow of blood through your heart and blood vessels.
Cardiac catheterization is usually done in a hospital. You will be awake during the procedure. It usually causes little or no pain, although you may feel some soreness in the blood vessel where your doctor inserts the catheter.