Medical & Biological Engineering & Computing

, Volume 57, Issue 2, pp 389–400 | Cite as

Short-term QT interval variability in patients with coronary artery disease and congestive heart failure: a comparison with healthy control subjects

  • Yang Li
  • Peng Li
  • Xinpei Wang
  • Chandan Karmakar
  • Changchun LiuEmail author
  • Chengyu Liu
Original Article


This study aimed to test how different QT interval variability (QTV) indices change in patients with coronary artery disease (CAD) and congestive heart failure (CHF). Twenty-nine healthy volunteers, 29 age-matched CAD patients, and 20 age-matched CHF patients were studied. QT time series were derived from 5-min resting lead-II electrocardiogram (ECG). Time domain indices [mean, SD, and QT variability index (QTVI)], frequency-domain indices (LF and HF), and nonlinear indices [sample entropy (SampEn), permutation entropy (PE), and dynamical patterns] were calculated. In order to account for possible influence of heart rate (HR) on QTV, all the calculations except QTVI were repeated on HR-corrected QT time series (QTc) using three correction methods (i.e., Bazett, Fridericia, and Framingham method). Results showed that CHF patients exhibited increased mean, increased SD, increased LF and HF, decreased T-wave amplitude, increased QTVI, and decreased PE, while showed no significant changes in SampEn. Interestingly, CHF patients also showed significantly changed distribution of the dynamical patterns with less monotonously changing patterns while more fluctuated patterns. In CAD group, only QTVI was found significantly increased as compared with healthy controls. Results after HR correction were in common with those before HR correction except for QTc based on Bazett correction.

Graphical abstract

Fig. The framework of this paper. The arrows show the sequential analysis of the data.


QT interval variability QT variability index Sample entropy Permutation entropy Dynamical patterns 



We would like to thank all the volunteers and researchers who participated in this study.

Funding information

This work was supported by the National Natural Science Foundation of China (Nos. 61471223, 61601263, 61501280), Shandong Provincial Natural Science Foundation of China (No. ZR2015FQ016), and the Excellent Young Scientist Awarded Foundation of Shandong Province (No. BS2012DX019).

Compliance with ethical standards

Informed consents were obtained from all subjects. The study was approved by the Clinical Ethics Committee of Shandong Provincial Qianfoshan Hospital.


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Copyright information

© International Federation for Medical and Biological Engineering 2018

Authors and Affiliations

  • Yang Li
    • 1
  • Peng Li
    • 1
  • Xinpei Wang
    • 1
  • Chandan Karmakar
    • 2
  • Changchun Liu
    • 1
    Email author
  • Chengyu Liu
    • 3
  1. 1.School of Control Science and EngineeringShandong UniversityJinanPeople’s Republic of China
  2. 2.School of Information TechnologyDeakin UniversityMelbourneAustralia
  3. 3.School of Instrument Science and EngineeringSoutheast UniversityNanjingPeople’s Republic of China

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