Shah C P, Thakur R K, Reisdorff E J, Lane E, Aufderheide T P, Hayes O W
Thoracic and Cardiovascular Institute, Department of Internal Medicine, Michigan State University, East Lansing, USA.
Am Heart J. 1998 Sep;136(3):496-8. doi: 10.1016/s0002-8703(98)70226-1.
QT dispersion has been proposed as a noninvasive measurement of the degree of inhomogeneity in myocardial repolarization. Increased QT dispersion has been reported after myocardial infarction. We hypothesized that increased QT dispersion may be a useful adjunct for risk stratification in patients being evaluated in a chest pain center.
Patients were admitted to the chest pain center for evaluation of chest pain. Exclusion criteria included (1) systolic blood pressure <90 mm Hg, (2) ischemia or infarction on the initial electrocardiograph (ECG), (3) elevated creatine kinase or MB fraction, and (4) chest pain associated with cocaine use. Serial creatine kinase and MB levels and ECGs were obtained at 0, 6, and 9 hours. Patients were monitored for (1) creatine kinase and MB rise, (2) ECG changes for infarction, (3) ST-segment changes, and (4) rest angina. A negative evaluation at the chest pain center led to an exercise stress test. Patients with a positive exercise stress test were admitted for further evaluation and patients with a negative exercise stress test result were discharged home. Patients were divided into 3 groups. Group 1 consisted of patients who were found to have an acute myocardial infarction (AMI), group 2 consisted of patients with prior history of coronary artery disease but no evidence of AMI, and group 3 consisted of patients without prior coronary artery disease or AMI. QT dispersion was measured on the initial ECG in all patients. A total of 586 patients were evaluated. Group 1 consisted of 13 patients with mean QT dispersion of 44.6+/-18.5 ms, group 2 consisted of 267 patients with a mean QT dispersion of 10.0+/-13.8 ms, and group 3 consisted of 303 patients with a mean QT dispersion of 10.5+/-10.0 ms. Analysis of variance showed a significantly higher QT dispersion in patients who had AMI compared with other patients with chest pain (P< .001).
QT dispersion can be a useful diagnostic adjunct for detection of AMI in patients with chest pain with a normal ECG and normal cardiac enzymes.
QT离散度已被提议作为心肌复极不均一程度的一种非侵入性测量方法。据报道，心肌梗死后QT离散度增加。我们推测，QT离散度增加可能是胸痛中心评估患者风险分层的一种有用辅助手段。
患者因胸痛入住胸痛中心进行评估。排除标准包括：（1）收缩压<90 mmHg；（2）初始心电图（ECG）显示缺血或梗死；（3）肌酸激酶或肌酸激酶同工酶水平升高；（4）与使用可卡因相关的胸痛。在0、6和9小时获取系列肌酸激酶和肌酸激酶同工酶水平以及心电图。对患者进行监测，观察：（1）肌酸激酶和肌酸激酶同工酶升高情况；（2）梗死的心电图变化；（3）ST段变化；（4）静息性心绞痛。胸痛中心的阴性评估导致进行运动负荷试验。运动负荷试验阳性的患者入院进一步评估，运动负荷试验结果阴性的患者出院回家。患者分为3组。第1组由被发现患有急性心肌梗死（AMI）的患者组成，第2组由有冠心病病史但无AMI证据的患者组成，第3组由无既往冠心病或AMI的患者组成。对所有患者的初始心电图测量QT离散度。共评估了586例患者。第1组由13例患者组成，平均QT离散度为44.6±18.5 ms，第2组由267例患者组成，平均QT离散度为10.0±13.8 ms，第3组由303例患者组成，平均QT离散度为10.5±10.0 ms。方差分析显示，与其他胸痛患者相比，AMI患者的QT离散度显著更高（P<0.001）。
对于心电图和心脏酶正常的胸痛患者，QT离散度可能是检测AMI的一种有用诊断辅助手段。
