South Yorkshire Cardiac Centre, Northern General Hospital, Herries Road, Sheffield S57AU, UK.
Europace. 2010 Apr;12(4):553-60. doi: 10.1093/europace/euq024. Epub 2010 Mar 4.
The aim of this study was to compare the rate-dependent measures of repolarization in patients with and without inducible ventricular arrhythmias, and so to assess the potential arrhythmogenic role of rate-dependent heterogeneities in cardiac repolarization.
Two groups of patients were studied during invasive electrophysiological procedures for standard clinical indications. A normal group (n = 17) with supraventricular tachycardia, structurally normal hearts and no inducible ventricular arrhythmias (PES-) and an inducible group (n = 13) with inducible ventricular arrhythmias (PES+). In each patient, we delivered a series of S1-S2 pacing sequences with a baseline S2 of 500 ms, which was progressively reduced. At the same time, a 12-lead electrocardiogram (ECG) was recorded. T-waves were extracted from each ECG recording, and 12 different T-wave measures were obtained from each patient across a range of coupling intervals. These included conventional measures, and those obtained from principal component analysis (PCA) of repolarization waveforms.
At baseline S2, there was no significant difference between the PES- and PES+ using conventional T-wave measures. There were significant differences at baseline S2 between groups using PCA-derived measures. These differences showed rate dependence and were larger at shorter coupling intervals. Two dynamic ECG measurements identified subjects who were inducible during PES; maximum relative T-wave residuum >0.10 (odds ratio: 38.5, 95% CI: 4.7-318.5; P < 0.001) and maximum T-wave shape index <0.007 (odds ratio: 180.0, 95% CI: 10.2-3167.0; P < 0.001).
T-wave shape index is rate dependent and discriminates between PES- and PES+ patients. We propose that patients with inducible arrhythmias have rate-dependent heterogeneity of repolarization which could be a useful tool for risk stratification.
本研究旨在比较伴有和不伴有可诱发室性心律失常患者的复极速率依赖性指标，从而评估心脏复极速率依赖性异质性的潜在致心律失常作用。
两组患者均因标准临床适应证行介入性电生理检查。正常组（n=17）为室上性心动过速、结构正常心脏且无可诱发室性心律失常（PES-）患者，诱发性组（n=13）为可诱发室性心律失常（PES+）患者。在每位患者中，我们以 500ms 的基础 S2 递送电刺激 S1-S2 序列，逐步缩短 S2。同时，记录 12 导联心电图（ECG）。从每个 ECG 记录中提取 T 波，并从每位患者的一系列不同的 S2 时程中获得 12 个不同的 T 波指标。这些指标包括传统指标和从复极波形主成分分析（PCA）中获得的指标。
在基础 S2 时，PES-和 PES+两组患者之间使用传统 T 波指标无显著差异。使用 PCA 衍生指标时，两组患者之间存在显著差异。这些差异具有速率依赖性，在较短的耦合间隔时更大。两项动态 ECG 测量指标可识别 PES 时可诱发的患者；最大相对 T 波残留>0.10（优势比：38.5，95%可信区间：4.7-318.5；P<0.001）和最大 T 波形态指数<0.007（优势比：180.0，95%可信区间：10.2-3167.0；P<0.001）。
T 波形态指数具有速率依赖性，并可区分 PES-和 PES+患者。我们提出，具有可诱发心律失常的患者存在复极速率依赖性异质性，这可能是一种有用的风险分层工具。
