Incremental evaluation of exercise capacity as an independent predictor of coronary artery disease presence and extent.

To determine the independent incremental value of exercise capacity (METS) concerning the presence and extent of coronary artery disease, we analyzed data from 800 patients with suspected coronary disease who underwent both exercise testing and coronary angiography. We performed logistic regression analysis of clinical and exercise test data with an incremental design to mimic the usual flow of data acquisition. Separate analyses were performed concerning coronary disease presence (> or = 1 vessel with a > or = 50% lesion) and extent (three-vessel/left main disease). Diagnostic accuracy was determined by calculating receiver operating characteristic (ROC) curve areas. When considered alone, METS was a significant predictor of both presence and extent of disease. Multivariate analysis revealed that METS was an independent predictor of disease extent but not presence. However, comparison of ROC curve areas failed to show any loss of accuracy when METS was removed from the coronary disease extent analysis. Despite the strong univariate relationship between exercise capacity and coronary disease presence and extent and the independence of exercise capacity as a predictor of coronary disease extent, the lack of an additional incremental accuracy attributed to its consideration virtually cancels its value as a diagnostic variable for assessing both coronary disease presence and extent.