Asymptomatic Coronary Disease

Atherosclerotic plaques have to reach considerable size before producing myocardial ischemia, which usually causes patients to experience chest pain (angina pectoris). Because of the prevalence of coronary-artery disease in the West and the slow growth of most atherosclerotic plaques, some coronary-artery disease can be found in a large segment of the population, as shown by autopsies of healthy persons who died a violent death (such as were performed on the bodies of young soldiers killed in the Korean War). Thus symptom-producing coronary-artery disease represents only a fraction of the incidence of such disease in the general population.

In asymptomatic coronary-artery disease atherosclerotic plaques have not reached the critical size to interfere with coronary blood flow. However, in a subgroup of persons with asymptomatic coronary-artery disease, ischemia is induced much as in stable angina pectoris, but no chest pain results. This phenomenon, commonly known as silent ischemia, can be detected by conventional diagnostic methods, such as the treadmill exercise test, isotopic perfusion test, and Holter monitor test. The reason why myocardial ischemia in some instances fails to be signaled by chest pain has not been adequately determined. Many patients with stable

angina pectoris suffer from attacks of silent ischemia in addition to attacks of chest pain; that is, myocardial ischemia occurs more frequently than they are aware of.

The discovery of silent ischemia in otherwise healthy persons, usually during a routine checkup, presents a dilemma. It is not yet known whether the prognosis of such patients is worse than that of similar people who do not show ischemia. It is uncertain whether the performance of invasive (angiographic) studies in cases of silent ischemia is indicated and whether intervention other than primary prevention of atherosclerosis is advisable.