Value of QT dispersion in the interpretation of treadmill exercise electrocardiograms of patients without exercise-induced chest pain or ST-segment depression

It has recently been reported that increased QT dispersion seen on standard TP-lead electrocardiograms (ECGs) reflects transient myocardial ischemia. The present study investigates whether increased QT dispersion induced by e xercise is a useful indicator for deflecting significant coronary stenosis in patients who do not have chest pain or significant ST-segment depression in response to exercise. We studied 135 consecutive patients (mean age +/- SD, 55 +/- 9 years; 97 men and 38 women) who complained of anginal chest p ain and who did not have exercise-induced chest pain or significant ST-segm ent depression during treadmill exercise electro-cardiography. Coronary ang iography was performed in all of patients, Of the 135 patients, 97 had no s ignificant coronary stenosis, 25 had 1-vessel coronary artery dis-ease (CAD ), and 13 had multivessel CAD, QT dispersion immediately after exercise was significantly greater in the group with significant coronary stenosis than without significant coronary stenosis (62 +/- 13 vs 40 +/- 14 ms, p <0.000 1). When QT dispersion greater than or equal to 60 ms immediately after exe rcise was considered a positive result, this indicator had a sensitivity of 74%, a specificity of 85%, and an accuracy of 81% far the diagnosis of sig nificant coronary stenosis, in conclusion, we have shown that QT dispersion immediately after exercise is useful for detecting significant CAD in pati ents who do not have exercise-induced chest pain or significant ST-segment depression. (C) 2000 by Excerpta Medica, Inc.