Diagnosis

If you have signs or symptoms associated with acute coronary syndrome, an emergency room doctor will likely order several tests. Some tests may be done while your doctor is asking you questions about your symptoms or medical history. Tests include:

• Electrocardiogram (ECG). Electrodes attached to your skin measure the electrical activity in your heart. Abnormal or irregular impulses can mean your heart is not working properly due to a lack of oxygen. Certain patterns in electrical signals may show the general location of a blockage. The test may be repeated several times.
• Blood tests. Certain enzymes may be detected in the blood if cell death has resulted in damage to heart tissue. A positive result indicates a heart attack.

The information from these two tests — as well as your signs and symptoms — is used to make a primary diagnosis of acute coronary syndrome. Your doctor can use the information to determine whether your condition can be classified as a heart attack or unstable angina.

Other tests may be done to learn more about your condition, rule out other causes of symptoms, or to help your doctor personalize your diagnosis and treatment.

• Coronary angiogram. This procedure uses X-ray imaging to see your heart's blood vessels. A long, tiny tube (catheter) is threaded through an artery, usually in your arm or groin, to the arteries in your heart. A dye flows through the tube into your arteries. A series of X-rays show how the dye moves through your arteries, revealing any blockages or narrowing. The catheter may also be used for treatments.
• Echocardiogram. An echocardiogram uses sound waves, directed at your heart from a wand-like device, to produce a live image of your heart. An echocardiogram can help determine whether the heart is pumping correctly.
• Myocardial perfusion imaging. This test shows how well blood flows through your heart muscle. A tiny, safe amount of radioactive substance is injected into your blood. A specialized camera takes images of the substance's path through your heart. They show your doctor whether enough blood is flowing through heart muscles and where blood flow is reduced.
• Computerized tomography (CT) angiogram. A CT angiogram uses a specialized X-ray technology that can produce multiple images — cross-sectional 2-D slices — of your heart. These images can detect narrowed or blocked coronary arteries.
• Stress test. A stress test reveals how well your heart works when you exercise. In some cases, you may receive a medication to increase your heart rate rather than exercising. This test is done only when there are no signs of acute coronary syndrome or another life-threatening heart condition when you are at rest. During the stress test, an ECG, echocardiogram or myocardial perfusion imaging may be used to see how well your heart works.