Follow-up Tests after Heart Attack
Before heart attack patients are discharged from the hospital, a stress test and/or a cardiac catheterization usually is performed. The primary purpose of a stress test is to determine if one or more of the coronary arteries has a significant blockage that is likely to cause problems in the near future. If a blockage is indicated by a stress test, cardiac catheterization is performed to obtain images of the coronary arteries.
Several types of "stress tests" may be used. In some cases, a patient simply walks on a treadmill while connected to an electrocardiogram. In other cases, a drug is infused into the bloodstream to increase the heart rate or to affect the flow of blood within the heart and an echocardiogram is used to obtain images of the heart.
Nuclear stress test involves injecting a radioactive substance into a vein and using a special camera to obtain images of the heart during rest and immediately following exercise on a treadmill. The radioactive substance is absorbed by normal heart tissue and following exercise, areas of diminished blood flow appear as relative "cold spots" on the images.
In some cases, the physician will omit the stress test and proceed directly to cardiac catheterization, which produces images of the coronary arteries and enables the physician to assess heart damage. In this procedure, a special catheter is inserted into the left ventricle, usually through the femoral artery in the groin. Iodine-based dye (contrast agent) is then injected through the catheter into the left ventricle, and images are taken of ventricle function. The infusion of dye typically produces a characteristic "hot flash" sensation throughout the body that lasts 10 to 15 seconds.
The advantage of first undergoing a stress test is that it may indicate that cardiac catheterization is unnecessary. The advantage of proceeding directly to cardiac catheterization is that it can determine the degree of blockage quickly and accurately and allow for prompt treatment.
The decision to perform a stress test first depends on many factors. In most cases, elderly patients and those in poor health may not be good candidates for cardiac catheterization and should be assessed via stress test first. Patients who have significant complications from a heart attack and those who have recurrent chest pain despite medical therapy usually require cardiac catheterization.