活动平板试验QTc离散度变化对冠心病的诊断意义

Significance of QTc Interval Dispersion Vary in Exercise Treadmill Test onDiagnosis of Coronary Heart Disease

目的 研究活动平板运动试验后QTc离散度变化对冠心病诊断的意义。方法 经冠状动脉造影证实为冠心病的患者 32例 ,冠状动脉正常者 2 8例。分析比较两组活动平板运动前和运动后即刻、2min及 4min12导联心电图QTc离散度变化及ST段变化。结果 运动前和运动后即刻、2min及 4min冠心病组QTc离散度分别为 :(4 2± 11)ms;(6 5± 12 )ms ;(6 0± 15 )ms;(4 8± 11)ms。运动后各时间点QTc离散度比运动前明显升高(P <0 0 1) ;冠状动脉正常组运动前、运动后即刻、2min及 4minQTc离散度分别为 (36± 13)ms ;(39± 11)ms;(4 0± 12 )ms ;(38± 14)ms。运动后各时相QTc离散度与运动前比较无明显差异 (P >0 0 5 ) ;运动后冠心病组QTc离散度比正常对照组均明显升高 (P <0 0 1)。以运动后即刻QTc离散度≥ 5 0ms为标准 ,诊断冠心病的敏感性为 84 6 %,特异性为 80 2 %,预测准确性为 87 5 %。高于运动后ST段阳性标准的改变 (P <0 0 5 )。结论运动高峰时QTc离散度增加有助于观察心肌缺血程度 ,可作为诊断冠心病的参考指标。

Objective This study was to investigate the effect of exercise-induced myocardial ischemia on QT interval dispersion in patients with coronary heart disease(CHD). Methods The changes of QTc of 12-lead surface electrocardiogram(ECG) measured before and at just stopping and at 2, 4 minute after exercise treadmill test(ETT) were analysesed in 32 patients with CHD and 28 patients with normal coronary artery identified by coronary angiography. Results In CHD group, the QT interval dispersion before and at just stopping and at 2, 4 minute after ETT were(42±11)ms; (65±12)ms; (60±15)ms; (48±11)ms respectively; QTc interval dispersion after EET were prolong significantly compared with that before ETT (P<0.01). In contrast, no obviously difference was found in QTc between before ETT and after ETT in control group [(36±13)ms; (39±11)ms; (40±12)ms; (38±14)ms](P>0.05)respectively. QTc before and after ETT in CHD group were increased significantly compared with that in normal coronary artery group(P<0.01). Stress QTc≥50 ms had a sensitivity of 84.6%, specificity of 80.2% and accuracy of 87.5%. Conclusion QTc was significantly increased in patients with CHD during ETT. A longer QTc at peak exercise may reflect the extent of myocardial ischemia. QTc during ETT could be used as a sensitive and specific index for diagnosis of CHD.