Moreno F L, Villanueva T, Karagounis L A, Anderson J L
University of Utah School of Medicine, Salt Lake City.
Circulation. 1994 Jul;90(1):94-100. doi: 10.1161/01.cir.90.1.94.
QT dispersion (QTd, equals maximal minus minimal QT interval) on a standard ECG has been shown to reflect regional variations in ventricular repolarization and is significantly greater in patients with than in those without arrhythmic events.
To assess the effect of thrombolytic therapy on QTd, we studied 244 patients (196 men; mean age, 57 +/- 10 years) with acute myocardial infarction (AMI) who were treated with streptokinase (n = 115) or anistreplase (n = 129) at an average of 2.6 hours after symptom onset. Angiograms at 2.4 +/- 1 hours after thrombolytic therapy showed reperfusion (TIMI grade > or = 2) in 75% of patients. QT was measured in 10 +/- 2 leads at 9 +/- 5 days after AMI by using a computerized analysis program interfaced with a digitizer. QTd, QRSd, JT (QT minus QRS), and JT dispersion (JTd, equals maximal minus minimal JT interval) were calculated with a computer. There were significant differences in QTd (96 +/- 31, 88 +/- 25, 60 +/- 22, and 52 +/- 19 milliseconds; P < or = .0001) and in JTd (97 +/- 32, 88 +/- 31, 63 +/- 23, and 58 +/- 21 milliseconds; P = .0001) but not in QRSd (25 +/- 10, 22 +/- 7, 28 +/- 9, and 24 +/- 9 milliseconds; P = .24) among perfusion grades 0, 1, 2, and 3, respectively. Similar results were obtained comparing TIMI grades 0/1 with 2/3 and 0/1/2 with 3. Patients with left anterior descending (versus right and left circumflex) coronary artery occlusion showed significantly greater QTd (70 +/- 29 versus 59 +/- 27 milliseconds, P = .003) and JTd (74 +/- 30 versus 63 +/- 27 milliseconds, P = .004). Similarly, patients with anterior (versus inferior/lateral) AMI showed significantly greater QTd (69 +/- 30 versus 59 +/- 27 milliseconds, P = .006) and JTd (73 +/- 30 versus 63 +/- 27 milliseconds, P = .007). Results did not change when Bazett's QTc or JTc was substituted for QT or JT or when ANOVA included adjustments for age, sex, drug assignment, infarct site, infarct vessel, and number of measurable leads. On ANCOVA, the relation of QTd or JTd and perfusion grade was not influenced by heart rate.
Successful thrombolysis is associated with less QTd and JTd in post-AMI patients. The results are equally significant when either QT or JT is used for analysis. These data support the hypothesis that QTd after AMI depends on reperfusion status as well as infarct site and size. Reduction in QTd and its corresponding risk of ventricular arrhythmia may be mechanisms of benefit of thrombolytic therapy.
标准心电图上的QT离散度（QTd，等于最大QT间期减去最小QT间期）已被证明可反映心室复极的区域差异，且在发生心律失常事件的患者中显著大于未发生者。
为评估溶栓治疗对QTd的影响，我们研究了244例急性心肌梗死（AMI）患者（196例男性；平均年龄57±10岁），这些患者在症状发作后平均2.6小时接受了链激酶治疗（n = 115）或茴酰化纤溶酶原链激酶激活剂治疗（n = 129）。溶栓治疗后2.4±1小时的血管造影显示75%的患者实现了再灌注（TIMI分级≥2级）。在AMI后9±5天，使用与数字转换器相连的计算机分析程序在10±2个导联上测量QT。使用计算机计算QTd、QRSd、JT（QT减去QRS）和JT离散度（JTd，等于最大JT间期减去最小JT间期）。在灌注分级0、1、2和3级中，QTd（分别为96±31、88±25、60±22和52±19毫秒；P≤.0001）和JTd（分别为97±32、88±31、63±23和58±21毫秒；P =.0001）存在显著差异，但QRSd（分别为25±10、22±7、28±9和24±9毫秒；P =.24）无显著差异。比较TIMI分级0/1与2/3以及0/1/2与3时，得到了类似结果。左前降支（与右冠状动脉和左旋支相比）冠状动脉闭塞的患者显示出显著更大的QTd（70±29对59±27毫秒，P =.003）和JTd（74±30对63±27毫秒，P =.004）。同样，前壁（与下壁/侧壁相比）AMI患者显示出显著更大的QTd（69±30对59±27毫秒，P =.006）和JTd（73±30对63±27毫秒，P =.007）。当用Bazett的QTc或JTc替代QT或JT，或者当方差分析包括对年龄、性别、药物分配、梗死部位、梗死血管和可测量导联数量进行调整时，结果不变。在协方差分析中，QTd或JTd与灌注分级的关系不受心率影响。
成功的溶栓治疗与AMI后患者QTd和JTd降低相关。当使用QT或JT进行分析时，结果同样显著。这些数据支持以下假设：AMI后的QTd取决于再灌注状态以及梗死部位和大小。QTd降低及其相应的室性心律失常风险降低可能是溶栓治疗获益的机制。
