Coronary Artery Disease
Examinations and Tests
To diagnose coronary artery disease (CAD), your health professional will complete a medical history and physical examination. Usually, the need for further testing depends on your risk factors and symptoms. Testing strategies also vary from doctor to doctor. Some tests, such as cardiac catheterization, may be available only at certain regional medical centres. The tests your doctor chooses may depend on how close you are located to a regional centre.
If coronary artery disease is suspected, you may have tests to determine the diagnosis. The most common initial tests are electrocardiogram (EKG or ECG), chest X-ray, routine blood tests, and exercise electrocardiogram, also called a "stress test."
Additional tests may include:5
- Cardiac perfusion scan. This test shows whether blood flow to the heart muscle is adequate.
- Echocardiogram and stress echocardiogram. This ultrasound test can identify areas of poor blood flow in the heart and injury to the heart muscle caused by a previous heart attack. It can also be used to estimate the amount of blood pumped out of your left ventricle with each heartbeat (ejection fraction).
- Coronary angiogram, or heart catheterization, a test that uses a dye to create images of blood flow through the coronary arteries and heart chambers. This catheter-based test is usually done only if bypass surgery or angioplasty is a reasonable option. For more information, see:
The following tests are not as common as other tests for CAD, but they may be needed in some cases to help your doctor better understand your condition.
- Intravascular ultrasound. This is a test that uses high-pitched sound waves (ultrasound) to detect fat and calcium buildup in the heart arteries.
- Magnetic resonance angiogram (MRA). This is a type of magnetic resonance image (MRI) scan that uses a magnetic field and pulses of radio wave energy to provide pictures of blood vessels inside the body. Currently, this test is only available in some large medical centres in Canada.
- Multislice CT scan. These special CT scans are faster than some other tests and can take better pictures of blood vessels and organs so other imaging tests may not be needed. Currently, this test is only available in some large medical centres in Canada.
Tests to measure risk for coronary artery disease
Blood pressure measurements determine if you have high blood pressure. High blood pressure is a risk factor for coronary artery disease.
Blood tests are often done to measure cholesterol levels. High cholesterol is also a risk factor for developing coronary artery disease.
The U.S. Preventive Services Task Force recommends that people with high blood pressure or high cholesterol be routinely screened for diabetes. This recommendation is based on studies that show people with diabetes benefit more from intensive treatment of high blood pressure and high cholesterol than people who do not have diabetes.6 The first screening test for diabetes is usually a fasting blood sugar test.
The American Heart Association and the U.S. Centers for Disease Control and Prevention (CDC) have released recommendations for C-reactive protein (CRP) blood testing. An increase in CRP levels is associated with inflammation in the blood vessels, atherosclerosis, and increased risk of coronary artery disease (CAD) and heart attack.7
The AHA/CDC panel recommends that CRP testing be done on some people who are at risk for developing coronary artery disease. If you have any CAD risk factors, ask your doctor whether CRP testing would be helpful in guiding your treatment.8 In Canada, this type of test for C-reactive protein is currently used only in large medical centres and research studies and is not yet widely available.
Elevated homocysteine levels and mutations of a specific gene (MTHFR) may also indicate an increased risk of coronary artery disease and heart attack, although more study is needed to fully understand their role in heart disease. Tests for these factors may be indicated for some people (for example, those who have had a heart attack at a young age or those with a strong family history of heart disease), but they are not recommended for the general population.
Another test, the coronary artery calcium score, can help detect whether you have coronary artery disease and may predict whether you will develop symptoms. To calculate your score, a computed tomography (CT) scan is used to measure calcification, or plaque, in the coronary arteries, which supply blood to the heart. If you have a high coronary artery calcium score, you may need more tests to check to see if you have CAD or to find out how severe it is, especially if you have other risk factors for CAD. The coronary artery calcium score test is not recommended for routine screening, because it can show that you may have plaque in your coronary arteries even if you do not have CAD.
Early detection
The American Heart Association has released new guidelines for screening for coronary artery disease. Several expert groups worked with the American Heart Association in creating these guidelines, which may be different from those your doctor follows. Work with your doctor to determine which guidelines are appropriate for you.
Beginning at age 20. Your doctor should assess your risk factors for heart disease during every routine examination. Risk factors include your family history of CAD, whether you smoke or are exposed to second-hand smoke, whether you eat a high saturated-fat diet, your alcohol intake, and your level of physical activity.
During every routine examination—at least every 2 years—a health professional should check your blood pressure, body mass index, and pulse. Based on your risk of high cholesterol and diabetes, you should have a fasting lipoprotein analysis to measure your total and HDL cholesterol, and a fasting blood glucose test. If risk factors are present, these tests should be done every 2 years. If you don't have risk factors, these tests should be done every 5 years.
At age 40 and over. Every 5 years, your 10-year risk of developing coronary artery disease should be assessed using a multiple risk factor score. This should be done more frequently if your risk factors change or if you have two or more risk factors. For example, a non-smoking, non-diabetic 55-year-old man who has a total cholesterol level of 5.2 mmol/L (200 mg/dL), an HDL level of 0.9 mmol/L (35 mg/dL), and a systolic blood pressure of 135 mm Hg has a 10% risk of developing CAD over the next 10 years. However, a 40-year-old man with the same risk factors but who smokes has the same risk of CAD as the 55-year-old non-smoker.
Additionally, most doctors recommend that you be tested for coronary artery disease if you are one of the following:
- Over age 39, have diabetes or more than one risk factor for CAD, and want to start a vigorous exercise program or are going to have major surgery
- Responsible for the lives of other people as part of your daily life (such as a pilot, bus driver, or sole caregiver for small children)
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| Author: | Douglas Dana Robin Parks, MS | Last Updated: September 21, 2007 |
| Medical Review: | Anne C. Poinier, MD - Internal Medicine Caroline S. Rhoads, MD - Internal Medicine Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology Robert A. Kloner, MD, PhD - Cardiology Ruth Schneider, MPH, RD - Diet and Nutrition | |
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