Faber T S, Zehender M, Krahnefeld O, Daisenberger K, Meinertz T, Just H
Universitätsklinik Freiburg, Abteilung für Kardiologie und Angiologie, Germany.
J Am Coll Cardiol. 1997 Mar 1;29(3):561-7. doi: 10.1016/s0735-1097(96)00555-4.
The proarrhythmic risk of class I antiarrhythmic agents in combination with myocardial ischemia is mainly the result of their effects on ventricular repolarization. This study was designed to evaluate the effect of class Ic antiarrhythmic agents on QT dispersion during myocardial ischemia.
QT interval dispersion on the 12-lead electrocardiogram (ECG) has been suggested as a noninvasive marker of inhomogeneous ventricular repolarization and susceptibility to ventricular arrhythmias.
In a randomized, double-blind study, 98 patients undergoing percutaneous transluminal coronary angioplasty (PTCA) were pretreated with propafenone or placebo. QT dispersion was defined as a maximal minus minimal QT interval on the 12-lead ECG before and after PTCA. The power of the study to detect clinically meaningful differences in QT dispersion was 0.75, and a twofold increase in QT dispersion in the propafenone group compared with the placebo group was considered clinically relevant.
The QT and corrected QT (QTc) intervals increased significantly during occlusion of the left anterior descending coronary artery (LAD) (9% and 11%, respectively, p < 0.05), whereas occlusion of the circumflex and right coronary arteries had no effect. QTc dispersion increased significantly in the propafenone group during ischemia (+52%, p = 0.002, vs. +23%, p = 0.15). The most considerable effect on QT dispersion was observed during LAD occlusion and ischemia of the anterior wall (+74%, p = 0.025). Corrected JT dispersion (+57%, p = 0.017, vs. +24%, p = 0.23) and the QT dispersion ratio (+1.6%, p = 0.031, vs. 0.9%, p = 0.34) showed similar effects. Plasma levels of propafenone (522 +/- 165 micrograms/liter) did not influence the results.
During myocardial ischemia, particularly during LAD occlusion, propafenone results in a significant increase in QT dispersion. The results indicate that QT interval prolongation and enhanced QT dispersion reflect inhomogeneous ventricular repolarization generated by the ischemic anterior wall of the myocardium. These observations may demonstrate a clinically important interaction between myocardial ischemia, repolarization variables and propafenone.
I类抗心律失常药物与心肌缺血联合应用时的促心律失常风险主要源于其对心室复极的影响。本研究旨在评估Ic类抗心律失常药物对心肌缺血期间QT离散度的影响。
12导联心电图（ECG）上的QT间期离散度已被认为是心室复极不均一性和室性心律失常易感性的无创标志物。
在一项随机、双盲研究中，98例行经皮腔内冠状动脉成形术（PTCA）的患者预先接受普罗帕酮或安慰剂治疗。QT离散度定义为PTCA前后12导联ECG上最大QT间期减去最小QT间期。该研究检测QT离散度临床有意义差异的效能为0.75，普罗帕酮组QT离散度相比安慰剂组增加两倍被认为具有临床相关性。
左前降支冠状动脉（LAD）闭塞期间QT和校正QT（QTc）间期显著增加（分别为9%和11%，p<0.05），而回旋支和右冠状动脉闭塞则无影响。缺血期间普罗帕酮组QTc离散度显著增加（+52%，p = 0.002，相比+23%，p = 0.15）。在LAD闭塞和前壁缺血期间观察到对QT离散度的影响最为显著（+74%，p = 0.025）。校正JT离散度（+57%，p = 0.017，相比+24%，p = 0.23）和QT离散度比值（+1.6%，p = 0.031，相比0.9%，p = 0.34）显示出相似的效应。普罗帕酮血浆水平（522±165微克/升）不影响结果。
在心肌缺血期间，尤其是在LAD闭塞期间，普罗帕酮导致QT离散度显著增加。结果表明QT间期延长和QT离散度增加反映了心肌缺血前壁产生的心室复极不均一性。这些观察结果可能证明了心肌缺血、复极变量和普罗帕酮之间临床上重要的相互作用。
