Calculation of probability of coronary artery disease

The probability of coronary artery disease (CAD) based upon a positive exercise test depends upon the pretest probability of CAD (ie, the prevalence of CAD in the population studied). The solid black bars indicate the results for a negative test (– ST) while the open red bars indicate the results for a positive test (+ ST). The results of a positive exercise test are less predictive in an asymptomatic population with a low pretest probability of CAD while they are very predictive in patients with typical angina who have a high pretest probability of CAD. The posttest probability of CAD is optimal in patients with an intermediate prevalence of CAD (eg, the 45-year-old with atypical chest pain).