In patients with atherosclerosis, the goal of diagnosis is to determine the location and the extent of the blockage. Atherosclerosis involving the heart and resulting in coronary artery disease may be diagnosed through several tests, including:

• Electrocardiogram (EKG). Following a medical history and physical examination, an EKG is a first-line diagnostic test to detect coronary artery disease. It is a recording of the heart’s electrical activity as a graph on a moving strip of paper or video monitor. The highly sensitive electrocardiograph machine helps detect heart irregularities, disease and damage by measuring the heart’s rhythms and electrical impulses. Easily performed, it can assist a physician in determining if the heart is receiving enough oxygen. The most critical role of an EKG is in patients with acute chest pain to detect a heart attack.
  
  
• Exercise stress test. If the heart is not receiving sufficient oxygen, the physician will likely want to determine whether exertion aggravates the condition. An exercise stress test is a special type of electrocardiogram that 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 under exertion can be measured and evaluated.
  
  
• Nuclear stress test. This test involves the administration of a radionuclide substance (e.g., thallium, myoview, sestamibi) into the bloodstream before taking very clear pictures with a gamma camera. Pictures may be taken both at rest and shortly after the stress of exercise. This gives the physician important information about where blockages of arteries may have occurred.
  
  
• Ultrafast computed tomography (ultrafast CT). This noninvasive imaging test takes multiple views of the heart. It can measure the amount of calcium in the arteries, which is an excellent indicator of how much calcification has occurred. Because calcified plaque is a sign of atherosclerotic buildup, this test can determine if individuals have an increased risk of coronary artery disease or heart attack regardless of whether symptoms are present. The results of this test are expressed as a calcium score. A low calcium score does not confirm the absence of a blocked artery, and a high calcium score may be associated with a blocked artery. The ultrafast CT is not a substitute for a physician’s evaluation, EKG and exercise stress test.

Where advanced coronary artery disease is suspected, a physician may want to perform a more invasive test called a coronary angiogram. A coronary angiogram is an x-ray of the arteries located on the surface of the heart (coronary arteries). It helps the physician to see if any of those arteries are blocked, usually by fatty plaque. If so, the patient may be diagnosed with coronary artery disease.

To take an angiogram, the physician injects a special dye (contrast medium) into the coronary arteries. To do that, the physician inserts a thin tube (catheter) through a blood vessel, usually in the upper thigh, and guides it all the way up to the heart. Once the catheter is in place, the physician can inject the dye through the catheter and into the coronary arteries. Then the x-ray can be taken. In some cases, blockages can be treated immediately through the catheter while it is still in place.