Coronary Angiography

Abstract

The need for any diagnostic test must be evaluated on the basis of the information it provides, the risk of the test, whether the same information could be provided by another, possibly less risky and less costly test, and the therapy it leads to. At present, coronary angiography is the only test that provides information about the site, extent, and severity of obstructive coronary artery disease. However, several questions about this procedure still remain unanswered. The ad hoc committee of the American Heart Association recommended in 1977 that routine coronary artery angiography after acute myocardial infarction was not indicated. There are, however, several authors who assert that there is a need for routine coronary angiography after acute myocardial infarction. The following reasons are given most frequently:

• 1. To assess prognosis: Angiographic studies have shown that the severity of coronary artery obstruction and the degree of left ventricular dysfunction are two major factors which influence survival in patients with coronary artery disease [1, 5, 6, 9, 10]. Angiographic studies of survivors of myocardial infarction have suggested a high incidence of multivessel coronary artery disease. From recent studies [2, 20] we have learned that the clinical course of patients with coronary artery disease is quite variable, even within the usual categories of one, two, and three-vessel disease or main stem stenosis. Still, in three-vessel disease only 50% of patients are alive at the end of 10 years, in contrast to the 10%–20% mortality of patients with single-vessel disease. Consequently, coronary angiography is of help in assessing prognosis in the individual patient, and the need to assess prognosis can be regarded as a valid reason for recommending coronary angiography in certain patients following myocardial infarction.

• 2. To recommend a program of physical exercise following myocardial infarction: The limits of exercise tolerance can be safely defined by noninvasive stress testing such as bicycle-ergometry and by radionuclide studies determining ventricular function under exercise. Thus, for the sole purpose of determining the safe margins of an exercise program, coronary angiography is not required. However, exercise studies following myocardial infarction are of limited value in detecting myocardium jeopardized by ischemia, and this limited sensitivity precludes their use as the yardstick for the final decision about the future management of the patient, particularly in the younger age group.

• 3. To determine optimal medical management: In regard to optimal medical management, it is not clear how knowledge of the site and extent of coronary artery obstruction would influence the decision about medical treatment. In the symptomatic patient following myocardial infarction, treatment will be given in accordance with the symptoms presented. In trials of secondary prevention after myocardial infarction, the routine administration of β-blocking agents has so far shown beneficial effects [9, 10, 12, 18, 20]. In these studies, coronary angiography was not required as an entry criterion; consequently, if treatment is given on this basis, coronary angiography will not be required.

• 4. To determine optimal surgical therapy: There is currently little doubt that surgery prolongs life in patients with left main stem and three-vessel coronary disease. In certain 180 P. Mathes subsets of patients with doube- and single-vessel disease, successful bypass surgery improves prognosis as well. It needs to be emphasized, however, that benefit obtained from coronary artery bypass surgery is prolonging the life of patients with coronary disease has been proven only in symptomatic patients [3, 4, 11]. Clearly, at a given stage of coronary artery disease the question of symptoms will largely depend upon the level of physical and emotional activity. Personality traits and denial will also influence the degree to which the symptoms are presented. One can therefore cautiously conclude that it appears reasonable to extrapolate the results observed in symptomatic patients to those patients presenting without severe symptoms, although data to substantiate this statement are still lacking.