Woźniak-Skowerska Iwona, Trusz-Gluza Maria, Skowerski Mariusz, Rybicka-Musialik Anna, Krauze Jolanta, Jaklik Andrzej, Myszor Jarosław, Cisowski Marek, Bochenek Andrzej
1st Department of Cardiology, Silesian Medical University, Katowice, Poland.
Med Sci Monit. 2004 Mar;10(3):CR128-31. Epub 2004 Mar 1.
Abnormal dispersion of the QT interval (QTd), measured as the interlead variability of QT, reflects an inhomogeneity of ventricular action potentials. In this study we observed both short- and long-term influences of coronary artery bypass grafting (CABG) on rest and exercise QTd in 64 male patients, having a mean age of 54+/-10 years, with coronary heart disease.
MATERIAL/METHODS: QTd was measured as the difference between QT maximum and minimum from 12 leads on an averaged ECG (25 mm/s). QTd and QTdc were measured at rest and at peak exercise during symptom-limited treadmill exercise (ET), which was performed before, 6 months after, and 2 years after CABG.
There was a significant reduction in rest QTd from before CABG to 6 months and 2 years after (60+/-20 ms vs. 43+/-14 ms and 45+/-13 ms, respectively; p<0.001). Similarly, there was a significant reduction in peak QTd from before CABG to 6 months and 2 years after (66+/-22 ms vs. 38+/-11 ms and 36+/-11 ms, respectively; p<0.001). Two years after CABG, 17 patients had a recurrence of angina and ET provoked chest pain and/or >2 mm ST depression. The resting values did not distinguish patients with ischemia from nonischemic ones. In patients with ischemia, ET provoked an increase in QTdc.
Rest and exercise QTd is significantly reduced after CABG. It seems that the measurement of QT dispersion during ET can be helpful in distinguishing patients with a recurrence of ischemia.
QT间期离散度（QTd）通过导联间QT间期的变异性来衡量，反映心室动作电位的不均一性。在本研究中，我们观察了64例平均年龄为54±10岁的男性冠心病患者冠状动脉旁路移植术（CABG）对静息和运动时QTd的短期和长期影响。
材料/方法：QTd通过平均心电图（25mm/s）上12导联QT最大值与最小值的差值来测量。在CABG术前、术后6个月和2年进行症状限制性平板运动试验（ET）时，测量静息和运动高峰时的QTd和QTdc。
从CABG术前到术后6个月和2年，静息QTd显著降低（分别为60± 20ms、43±14ms和 45±13ms；p<0.001）。同样，从CABG术前到术后6个月和2年，运动高峰QTd也显著降低（分别为66±22ms、38±11ms和36±11ms；p<0.001）。CABG术后2年，17例患者心绞痛复发，ET诱发胸痛和/或ST段压低>2mm。静息值无法区分缺血患者和非缺血患者。在缺血患者中，ET诱发QTdc增加。
CABG术后静息和运动时的QTd显著降低。似乎在ET期间测量QT离散度有助于区分缺血复发患者。
