运动试验QT离散度变化与心肌缺血或T波改变相关性的研究

目的 :探讨运动试验QT离散度 (QTd)变化与心肌缺血和T波变化的相关性及评价QTd的临床应用价值。方法 :2 4 2例经冠脉造影证实冠心病而静息心电图正常 ,平板运动试验阳性 (冠心病组 )和 16 8例静息心电图有T波低平、双向、倒置或有u波 ,平板运动试验心电图正常 ,并经冠脉造影及其他检查排除器质性心脏病 (非器质性心脏病组 )。观察两组平板运动试验QTd的变化与心肌缺血和T波变化的相关性。结果 :设QTd >5 0ms为异常 ,冠心病组运动前QTd异常率为18% ,运动后为 80 % ;非器质性心脏病组运动前QTd异常率为 84 % ,运动后为 12 %。QTd的变化与T波改变相关 ,r=0 .86 ,P <0 .0 1;与冠心病运动后单纯缺血性ST段下移无相关性。结论 :运动试验QTd变化与心肌缺血无相关性 ,QTd异常不能判断心肌复极不均一性进而预测恶性心律失常或心脏猝死 ,而只是反映T波非特异性异常的一个粗浅的量化指标

Investigation of the Relationship between Myocardial Ischemia or T Wave Changes and QT Dispersion during the Exercise Test

Objective: To investigate the relationship between the myocardial ischemia or T wave changes and QT dispersion (QTd) during the exercise test and evaluate the clinical significance of QTd. Methods: All subjects underwent a modified Bruce protocol exercise test and QT intervals were measured manually at rest and during exercise. The value of QTd was calculated as a difference between the longest and the shortest value measured in each of the 12 leads ECG.Of 410 patients studied,242 patients with coronary heart disease and 168 patients with non heart disease verified by coronary angiography and other examinations,ECGs were normal before exercise test and abnormal after exercise in patients with coronary angiography positive patients (CHD group). ECGs were abnormal with T wave inversion,low or discovered u wave before exercise test and were normal after exercise in patients with coronary angiography negative patients (non heart disease group).Results: In CHD group QTd were abnormal in 18% patients before exercise and 80% after exercise. In non heart disease group abnormal QTd were 84% before exercise and 12% after exercise. Conclusion: Increased QTd is neither always associated with myocardial ischemia and nor an risk mark for ventricular arrhythmias and sudden death.Increased QT dispersion only reflects nonspecific T wave changes.