Aim:To determine if there is an association between the QT dispersion (QTd) and the coronary artery pathological changes such as the number of diseased vessels, the extent and location of luminal narrowing in a sample of patients with coronary artery disease (CAD). And also observe if there are changes of the QTd in the CAD patients who combined with diabetes mellitus by u-sing the β-receptor blocker Metoprolol. Methods: One hundred and ninety-two patients were selected , who were performed coronary angiography with integrity clinical and electrocardiogram ( ECG)data, and divided randomly into groups as CAD group and group without CAD according to the results of coronary angiography, and in the CAD group, it is again divided into three subgroups such as monvessel disease (n =43) , bivessel disease (n =54) and multivessel disease (n =46) ,and divided the monvessel disease group patients into another 3 groups; left anterior descending branch( n = 19 ) , left circumflux branch ( n = 11) and right coronary artery ( n = 13 ). And we also divided all the selected patients into group with moderate luminal narrowing( n -57) and severe luminal narrowing ( n = 86 ) according to the extent of the coronary artery stenosis. And we divided the patients into diabetes mellitus group ( n = 76 ) and non diabetes mellitus ( n = 67 ) group. QTds of all the patients in every group were measured. Then the patients in diabetes mellitus group were randomly divided into treated group ( n = 45 ) who were treated with the β-receptor blocker Metoprolol and con-trol group ( n = 31) who were treated with the routine proposal and observed the difference of QTd a-mong them. Results: QTd and QTcd in the CAD group and diabetes mellitus group were significantly prolonged compared with the non-CAD group and non-diabetes mellitus group respectively ( P < 0. 05) ; as the affected vessels and the severity of the diseased vessels increased, QTds were obviously prolonged ( P < 0. 05 ) ; the location of the coronary artery stenosis had no effect on the QTd in the subgroup of monvessel disease ( P > 0. 05 ) ; and when patients treated with Metoprolol, their QTds were significantly shortened compared with the control group and themselves before the treatment. Conclusion: QTd is prolonged in the patients with coronary artery disease, and as the numbersof affected vessels and the severity of stenosis of the diseased vessels increased, QTds were obviously prolonged, indicate the aggravation of myocardial ischemia and myocardial injury. QTds of the patients with coronary artery diseased combined diabetes mellitus are obviously prolonged and Metoprolol can shorten them significantly. QTd is a significant index to evaluate myocardial ischemia and myocardial injury.%目的:探讨冠心病患者QT离散度(QT dispersion,QTd)与冠状动脉(简称冠脉)病变狭窄程度及累及血管支数的关系,并观察冠心病合并糖尿病患者予以美托洛尔治疗后QTd的变化.方法:选择192例行冠状动脉造影且心电图资料完整者,据造影结果分为非冠心病组49例和冠心病组143例；冠心病组依冠脉病变支数分为单支病变组43例、双支病变组54例和三支病变组46例,依狭窄程度分为轻度狭窄组57例和重度狭窄组86例,依合并糖尿病与否分为冠心病非糖尿病组67例和冠心病合并糖尿病组76例；对冠心病并糖尿病组76例随机分为治疗组45例和对照组31例,观察美托洛尔治疗前后QTd的变化.结果:冠心病组较非冠心病组、冠心病合并糖尿病组较冠心病非糖尿病组QTd均明显延长(P＜0.05)；随着冠脉病变支数增加及狭窄程度加重,组间比较QTd均明显延长(P＜0.05)；冠心病合并糖尿病组美托洛尔治疗后较治疗前及较对照组治疗后QTd均明显缩短(P＜0.05).结论:冠心病患者QTd延长,QTd与冠脉病变血管狭窄程度以及累及的血管支数有关,随着冠脉狭窄程度的加重以及冠脉病变血管支数的增加,心肌缺血及损伤程度越重,其QTd延长越明显.冠心病合并糖尿病患者QTd显著延长,予以美托洛尔治疗后QTd显著缩短.
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