Schmidt Martin, Baumert Mathias, Malberg Hagen, Zaunseder Sebastian
Institute of Biomedical Engineering, Technische Universität Dresden Dresden, Germany.
School of Electrical and Electronic Engineering, The University of Adelaide Adelaide, SA, Australia.
Front Physiol. 2016 Jun 7;7:216. doi: 10.3389/fphys.2016.00216. eCollection 2016.
The inverse relationship between QT interval variability (QTV) and T wave amplitude potentially confounds QT variability assessment. We quantified the influence of the T wave amplitude on QTV in a comprehensive dataset and devised a correction formula.
Three ECG datasets of healthy subjects were analyzed to model the relationship between T wave amplitude and QTV. To derive a generally valid correction formula, linear regression analysis was used. The proposed correction formula was applied to patients enrolled in the Evaluation of Defibrillator in Non-Ischemic Cardiomyopathy Treatment Evaluation trial (DEFINITE) to assess the prognostic significance of QTV for all-cause mortality in patients with non-ischemic dilated cardiomyopathy.
A strong inverse relationship between T wave amplitude and QTV was demonstrated, both in healthy subjects (R (2) = 0.68, p < 0.001) and DEFINITE patients (R (2) = 0.20, p < 0.001). Applying the T wave amplitude correction to QTV achieved 2.5-times better group discrimination between patients enrolled in the DEFINITE study and healthy subjects. Kaplan-Meier estimator analysis showed that T wave amplitude corrected QTVi is inversely related to survival (p < 0.01) and a significant predictor of all-cause mortality.
We have proposed a simple correction formula for improved QTV assessment. Using this correction, predictive value of QTV for all-cause mortality in patients with non-ischemic cardiomyopathy has been demonstrated.
QT间期变异性（QTV）与T波振幅之间的反比关系可能会混淆QT变异性评估。我们在一个综合数据集中量化了T波振幅对QTV的影响，并设计了一个校正公式。
分析了三个健康受试者的心电图数据集，以建立T波振幅与QTV之间的关系模型。为了得出一个普遍有效的校正公式，使用了线性回归分析。将所提出的校正公式应用于参加非缺血性心肌病治疗评估试验（DEFINITE）中的除颤器评估的患者，以评估QTV对非缺血性扩张型心肌病患者全因死亡率的预后意义。
在健康受试者（R（2）=0.68，p<0.001）和DEFINITE患者（R（2）=0.20，p<0.001）中均证实了T波振幅与QTV之间存在强烈的反比关系。对QTV应用T波振幅校正后，DEFINITE研究中的患者与健康受试者之间的组间区分能力提高了2.5倍。Kaplan-Meier估计分析表明，T波振幅校正后的QTVi与生存率呈负相关（p<0.01），并且是全因死亡率的重要预测指标。
我们提出了一个简单的校正公式，以改进QTV评估。使用这种校正方法，已证明QTV对非缺血性心肌病患者全因死亡率具有预测价值。
