A coronary angiogram (or arteriogram) is one of the most accurate tests in the diagnosis of coronary artery disease (CAD), and over a million of them are conducted each year. The angiogram is used to pinpoint the location and severity of CAD. For example, it can reveal blockage in an artery due to either a buildup of plaque or abnormalities in the wall of the heart.

An angiogram is a relatively safe, though minimally invasive, test. The test may be administered if CAD is suspected because of symptoms such as:

An angiogram may also be done if the results of less invasive tests were abnormal. These tests may include:

• Electrocardiogram (EKG). An EKG is a recording of the heart’s electrical activity as a graph on a moving strip of paper. It helps to detect heart irregularities, disease and damage by measuring the heart’s rhythms and electrical impulses.
  
  
• Exercise stress test. An EKG is performed while the patient exercises in a controlled manner on a treadmill or stationary bicycle at varied speeds and elevations. The reaction of the heart during physical activity can be measured and compared with the heart’s function while at rest.
  
  
• Echocardiogram. This test uses sound waves to track the structure and function of the heart. A moving image of the patient’s beating heart is played on a monitor screen, where a physician can study the heart’s thickness, size and function. The image also shows the motion pattern and structure of the four heart valves, revealing any potential leakage regurgitation or narrowing stenosis. During this test, a Doppler ultrasound may also be done to evaluate blood flow and measure the severity of any regurgitation and/or stenosis.
  
  
• Nuclear stress test. A type of stress test that involves the injection of a small, harmless amount of a substance with special radionuclide properties, such as thallium. The rays emitted from this substance while in the heart allow a gamma camera to create images of the heart before, during and after physical exercise.

In patients with previous coronary artery bypass surgery, angiography of the grafts can detect any blockage or other abnormalities of these grafts.