Koide Y, Yotsukura M, Tajino K, Yoshino H, Ishikawa K
Kyorin University, School of Medicine, Tokyo, Japan.
Clin Cardiol. 2000 Apr;23(4):277-84. doi: 10.1002/clc.4960230411.
The presence of ischemic but viable myocardium in infarcted areas is an important indication for coronary revascularization, but is often difficult to detect with the use of treadmill exercise electrocardiography (ECG).
QT interval dispersion (QTd) is a sensitive method for detecting myocardial ischemia and may improve the accuracy of treadmill exercise ECG testing for detecting ischemic but viable myocardium in infarcted areas.
Forty-five patients with Q-wave anterior wall myocardial infarctions who underwent treadmill exercise ECG, exercise reinjection thallium-201 (201Tl) scintigraphy, radionuclide angiocardiography, and coronary angiography 1 month after infarction were enrolled in this study. The presence of viable myocardium in the infarct area was determined by exercise reinjection 201Tl scintigraphy. Patients who had no redistribution in the infarct area after reinjection were included in Group 1, and those with redistribution were included in Group 2.
QTd immediately after exercise, and the difference between QTd before and immediately after exercise, were significantly greater in Group 2 than in Group 1. The sensitivity, specificity, and accuracy of conventional ST-segment depression criteria for detecting viable myocardium in the infarct area were 48, 64, and 56%, respectively. The measurement of QTd immediately after exercise (abnormal: > or = 70 ms; normal: < 70 ms) improved the sensitivity, specificity, and accuracy to 78, 82, and 80%, respectively.
This novel diagnostic method using QTd-based criteria significantly improves the clinical usefulness of treadmill exercise ECG testing for detecting ischemic but viable myocardium in infarct areas in patients with healed Q-wave anterior wall myocardial infarctions.
梗死区域存在缺血但存活的心肌是冠状动脉血运重建的重要指征，但使用平板运动心电图（ECG）检测时往往很难发现。
QT间期离散度（QTd）是检测心肌缺血的一种敏感方法，可能会提高平板运动心电图检测梗死区域缺血但存活心肌的准确性。
本研究纳入了45例Q波前壁心肌梗死患者，这些患者在梗死后1个月接受了平板运动心电图、运动再注射铊-201（201Tl）心肌显像、放射性核素心血管造影和冠状动脉造影检查。通过运动再注射201Tl心肌显像确定梗死区域存活心肌的存在情况。再注射后梗死区域无再分布的患者纳入第1组，有再分布的患者纳入第2组。
运动后即刻QTd以及运动前与运动后即刻QTd的差值，第2组显著大于第1组。传统ST段压低标准检测梗死区域存活心肌的敏感性、特异性和准确性分别为48%、64%和56%。运动后即刻测量QTd（异常：≥70毫秒；正常：<70毫秒）可将敏感性、特异性和准确性分别提高到78%、82%和80%。
这种基于QTd标准的新型诊断方法显著提高了平板运动心电图检测愈合Q波前壁心肌梗死患者梗死区域缺血但存活心肌的临床实用性。
