To diagnose coronary artery disease (CAD), your health professional will complete a medical history and physical exam. Usually, the need for further testing depends on your risk factors and symptoms. Testing strategies also vary from doctor to doctor.

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:

  Should I have an angiogram to test for coronary artery disease?

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 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

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.