Prevalence of silent ischemia in patients undergoing coronary angiography

One problem in the spectrum of silent myocardial ischemia, which is difficult to ascertain, is its prevalence. Yet the prevalence is of great importance if one wants to understand the medical and socio-economic impact of this disease state. Bayesian analysis (8, 22) has shown that prevalence, or “pre-test-likelihood”, has a decisive influence on the usefulness of a diagnostic test in a given patient population. This poses a special problem for the physician dealing with silent ischemia in asymptomatic patients, as there is no prevalence of symptoms to start with, but the disease state needs objective testing for its definition. Information on prevalence of asymptomatic coronary artery disease can be obtained either from post mortem studies or coronary angiography. Results from the study by Diamond and Forrester (8), an example of this type of study, suggested that the prevalence of asymptomatic coronary artery disease in adults is around 5%. This figure increased with age and sex, e.g. to 12% for over 60-year-old males.