Prevention Conference V

riting Group II addressed the question of whether tests that assess silent ischemia or inducible ischemia add to prognostic information gained from standard risk factors in asymptomatic patients without known coronary disease.The tests reviewed included the exercise electrocardiogram (ECG), exercise and pharmacological (stress) echocardiogram (echo), exercise and pharmacological myocardial perfusion imaging, ambulatory ECG monitoring, and positron emission tomography.These noninvasive tests detect myocardial ischemia associated with obstructive coronary artery disease (CAD).To date, their greatest application has been diagnostic, in the evaluation of patients with symptoms of angina or a previous clinical manifestation of coronary heart disease (CHD).One limitation of the methods used to detect stress-induced (exercise or pharmacological stress) myocardial ischemia is the dependence of these methods on the presence of flowlimiting coronary stenosis.As with all diagnostic studies, their predictive value is dependent on the prevalence of disease in the population tested.When used in a population with a low prevalence of CHD, such as an asymptomatic population undergoing cardiovascular screening, these tests are expected to have low positive predictive value, and the majority of positive test results represent false-positive responses (Figure).Also central to the discussions of Writing Group II was the recognition that the majority of future events among patients with CHD are related to severity of obstruction, plaque instability, and total atherosclerotic burden. 1 Writing Group II was specifically concerned with delineating the prognostic information available from these tests that could contribute toward identifying patients at higher risk for major CHD-related events.