Comparison of QRS Score, a New Exercise Index,and Conventional ST Segment Criterion in Detecting Coronary Artery Disease

Although ST segment depression, during exercise stress test (EST) is the most commonly used electrocardiographic (ECG) criterion for myocardial ischemia, its diagnostic value is limited because of low sensitivity and specificity. It was shown that not only ST depression, but also Q, R and S wave changes occur during EST, but these changes also have limited value in the diagnosis of myocardial ischemia when evaluated individually. However, it was hypothesized that incorporation of these individual changes with exercise, into a composite index (QRS score) might improve sensitivity and specificity. In this study, the diagnostic value of this new exercise index in detecting myocardial ischemia was investigated and its sensitivity and specificity was compared with the conventional ST segment criterion. For this purpose, ı 7 ı patients were enrolled in the study and divided into 3 groups as group 1: normal coronary artery group (n=55), group 2: patients with one-vessel disease (n=73), group 3: patients with multi-vessel disease (n=43). All patients underwent maximal EST with standard Bruce protocol and coronary angiography. Using a cut-off point of ~O as normal, QRS score had a higher sensitivity than ST segment criterion in all patients (79% and 65%, respectively, p<0.005), however, no difference existed in specificity and positive predictive value. In one-vessel disease group (group 2), QRS score had a sensitivity of 77%, whereas conventional ST segment criterion had a sensitivity of 56% (p