Usefulness of QT dispersion immediately after exercise as an indicator of coronary stenosis independent of gender or exercise-induced ST-segment depression

Several recent studies suggest that QT dispersion on a standard 15-lead ele ctrocardiogram is a clinically useful indicator of significant coronary ste nosis. In this study, we compared the diagnostic accuracy of QT dispersion immediately after exercise as an indicator of coronary stenosis in men and women, and in the presence or absence of exercise-induced significant ST-se gment depression. The subjects were 273 consecutive patients (mean age 56 /- 9 years; 190 men and 83 women) without a history of myacardial infarctio n who underwent treadmill exercise electrocardiography and coronary angiogr aphy for evaluation of angina. Of these, 146 patients had no significant co ronary stenosis, 61 had single-vessel disease, 56 had multivessel disease, and 10 had left main coronary artery disease. QT dispersion immediately aft er exercise was significantly greater in patients with significant coronary stenosis than in those without (64 +/- 14 vs 39 +/- 14 ms, p <0.01). QT di spersion immediately after exercise was significantly more sensitive in men (sensitivity 75%; specificity 85%) and significantly more specific in wome n (sensitivity 77%, specificity 88%) than exercise-induced significant ST-s egment depression (men: sensitivity 62%, specificity 74%; women: sensitivit y 81%, specificity 68%) as an indicator of significant coronary stenosis. T he addition of factors such as gender and the presence or absence of exerci se-induced significant ST-segment depression did not significantly alter th e sensitivity and specificity of QT dispersion immediately after exercise f or detecting significant coronary stenosis (patients with significant ST-se gment depression: sensitivity 77%, specificity 88%; patients without signif icant ST-segment depression: sensitivity 72%, specificity 86%). In conclusi on, QT dispersion immediately after exercise is a clinically useful indicat or of significant coronary stenosis independent of gender or the presence o r absence of exercise-induced significant ST-segment depression. (C)2000 by Excerpta Medica, Inc.