Atiga W L, Calkins H, Lawrence J H, Tomaselli G F, Smith J M, Berger R D
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
J Cardiovasc Electrophysiol. 1998 Sep;9(9):899-908. doi: 10.1111/j.1540-8167.1998.tb00130.x.
Recent studies have implicated repolarization lability in the genesis of malignant ventricular arrhythmias. However, few data exist on assessment of temporal QT interval variability and its relation to arrhythmogenesis. We tested the ability of the QT variability index (QTVI), a measure of beat-to-beat QT interval fluctuations measured on a single ECG lead, to identify patients presenting with malignant ventricular arrhythmias and predict their subsequent occurrences.
We measured the QTVI in 95 patients presenting for electrophysiologic study (EPS). The ability of the QTVI to identify patients with sudden cardiac death (SCD) or sustained monomorphic ventricular tachycardia (MVT) on presentation and during follow-up of 23.7+/-14.3 months was compared with spatial QT dispersion, T wave alternans ratio during atrial pacing, MVT inducibility at EPS, signal-averaged ECG, heart rate variability, and ejection fraction. The QTVI was higher in patients with heart disease than in controls (-0.7+/-0.7 vs -1.1+/-0.5, P < 0.05), and higher in patients presenting with SCD than in other patients with heart disease (0.0+/-0.6 vs -0.8+/-0.5, P < 0.05). The QTVI was the only clinical variable that identified patients who presented with SCD (P = 0.004, odds ratio = 12.5) on stepwise, logistic multiple regression. Fourteen patients had arrhythmic events during follow-up. In a Kaplan-Meier analysis of arrhythmic events, QTVI> or =0.1 was a discriminator for higher risk of arrhythmic events (P < 0.05).
(1) This noninvasive measure of temporal repolarization lability identified patients with SCD and predicted arrhythmia-free survival. (2) Further studies are needed to determine the mechanisms that mediate beat-to-beat QT interval variability.
最近的研究表明复极不稳定在恶性室性心律失常的发生中起作用。然而，关于评估QT间期的时间变异性及其与心律失常发生的关系的数据很少。我们测试了QT变异性指数（QTVI），一种在单导联心电图上测量逐搏QT间期波动的指标，识别出现恶性室性心律失常患者并预测其随后发作的能力。
我们测量了95例接受电生理检查（EPS）患者的QTVI。将QTVI在患者就诊时以及23.7±14.3个月随访期间识别心脏性猝死（SCD）或持续性单形性室性心动过速（MVT）患者的能力，与空间QT离散度、心房起搏时T波交替率、EPS时MVT诱发性、信号平均心电图、心率变异性和射血分数进行比较。心脏病患者的QTVI高于对照组（-0.7±0.7对-1.1±0.5，P<0.05），SCD患者的QTVI高于其他心脏病患者（0.0±0.6对-0.8±0.5，P<0.05）。在逐步逻辑多元回归中，QTVI是唯一能识别出现SCD患者的临床变量（P = 0.004，比值比 = 12.5）。14例患者在随访期间发生心律失常事件。在心律失常事件的Kaplan-Meier分析中，QTVI≥0.1是心律失常事件高风险的鉴别指标（P<0.05）。
（1）这种对复极时间不稳定性的非侵入性测量可识别SCD患者并预测无心律失常生存期。（2）需要进一步研究以确定介导逐搏QT间期变异性的机制。
