Improvement of the diagnostic value of exercise test by heart-rate adjusted segment depression. Value of ST 20/HR index]

One of the new criteria of positivity of exercise stress testing proposed by Detrano and Kligfield is the ST/HR index, obtained by calculating the ratio of additional ST depression on exercise over the corresponding variation in the heart rate. These authors reported that this ratio improved the diagnostic value of the exercise stress test with respect to the traditional ST segment depression, but that the proportion depended on whether the index was measured 80 or 60 ms after the J point. The object of this study was to assess the diagnostic performance of the ST/HR index measured 0, 20, 40, 60 and 80 ms after the J point by automatic analysis and to compare these five diagnostic indices with the classical ST segment depression (standard criterion) by ROC graphs and the Mac Nemar test. One hundred consecutive patients (73 men and 27 women) all symptomatic, underwent submaximal or symptom-limited exercise stress testing and accepted coronary angiography. The prevalence of greater than or equal to 50% coronary stenosis on at least one main vessel was 48%. None had previous myocardial infarction. The ROC graphs and areas under the curve demonstrated generally the superiority of the ST/HR index over the standard criteria. The optimal diagnostic performance was observed when the index was calculated 20 ms after the J point (ST 20/HR index).(ABSTRACT TRUNCATED AT 250 WORDS)