Noninvasive Testing of Silent Myocardial Ischemia

Abstract

The management of coronary disease constitutes a key clinical issue today. Both silent ischemia and angina are part of the broad spectrum of ischemia. Angina may be only the tip of the iceberg with frequent and prolonged episodes of silent ischemia present below the conscious surface. They both identify individuals with coronary disease who are at increased risk of having adverse cardiac events. To justify changing our approach to patient management, we require good evidence that the strategy of detecting and treating silent ischemia will improve the therapeutic outcome of our patients. Noninvasive testing may provide these guiddlines. There are three clinical subsets in which silent ischemia is commonly found: asymptomatic individuals without known coronary artery disease, those who are postmyocardial infarction, and those with known coronary disease. Noninvasive testing of asymptomatic individuals is difficult because of the low prevalence of coronary disease in this population, but identification of high-risk individuals can be accomplished by exercise testing patients with multiple risk factors. Sequential Bayesian analysis using independent noninvasive tests can improve the accuracy of predicting coronary disease when exercise testing results are equivocal. Testing of individuals after a myocardial infarction can identify individuals at increased risk for an adverse cardiac event. Early testing is critical because most events occur within a few months after a myocardial infarction. Noninvasive testing of individuals with chronic coronary disease can define dynamic coronary disease activity and identify high-risk individuals likely to have a future cardiac event. Early aggressive intervention in high-risk patients with silent ischemia may reduce the occurrence of adverse events.