Tests for CAD can be described as either invasive or noninvasive. An invasive test requires a device—a catheter, for instance—to enter the body. Noninvasive tests are diagnostic studies that provide information without entering the body's portals or making an incision. The difference is important, because invasive tests carry a greater risk of complications like infection and bleeding. The rapid pace of technological advances has made invasive studies less necessary, and one day they may become obsolete. Today, though, invasive tests are still an important means of diagnosing CAD.
Coronary Angiogram and Cardiac Catheterization
Arteries and veins don't show up on x-rays unless a special dye is injected into the body to make them visible. This dye, or contrast solution, is injected by means of a catheter—a long, flexible tube that's snaked up to the coronary arteries through an incision in the groin, arm, or neck. Arteries narrowed by plaque deposits can be identified easily once the dye has been released.
Coronary Calcium Scan
Plaque is composed, in part, of calcium. Calcium deposits in the arteries—a condition known as calcification—is an early indicator of CAD. Calcium shows up well on computed tomography (CT) scans, making the artery appear bright white. To look for calcification in the coronary arteries, a coronary calcium scan is performed. The amount of calcification found in the coronary arteries indicates the degree of atherosclerosis present. The patient's score on this test correlates with the likelihood that he or she will have a heart attack within a few years, but the results are difficult to interpret and must be considered along with the many other risk factors for CAD.
An electrocardiogram (commonly called an ECG or EKG) is a test in which the patient's heart rhythm and rate are evaluated by measuring the heart's electrical activity. The test records electrical impulses by means of a set of electrodes attached to the chest. The electrical activity is represented graphically by a rhythm strip.
An echocardiogram relies on ultrasound technology to create a dynamic picture of heart structure and function, including blood flow. An echocardiogram is sometimes combined with a stress test to allow visualization of the heart during exertion.
Exercise Stress Test
A stress test reveals how well the coronary arteries deliver oxygen-rich blood to the heart when the heart is put under stress. You may be asked to walk on a treadmill, or stress can be artificially induced with drugs that increase the heart rate. The heart's performance is tracked using electrocardiography or echocardiography and a blood pressure cuff.