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Related Concept Videos

Coefficient of Variation01:10

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The coefficient of variation measures the dispersion of the data points or distribution around the mean. Using the coefficient of variation, we can compare two data series with drastically different means or different units of measurement. The coefficient of variation for a sample and a population is expressed as a percentage of the ratio of standard deviation to the mean.
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QT Variability Index.

Craig P Dobson1, Andrew Kim, Mark Haigney

  • 1Department of Medicine, Division of Cardiology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA; Walter Reed National Military Medical Center, Bethesda, MD, USA.

Progress in Cardiovascular Diseases
|November 13, 2013
PubMed
Summary
This summary is machine-generated.

The QT Variability Index (QTVI) offers a non-invasive assessment of heart repolarization variability and autonomic tone. Further prospective studies are needed to confirm its clinical utility in guiding cardiovascular therapy.

Keywords:
APDCVCardiovascular mortalityHFHRVHeart failureICDLVEFNYHANew York Heart Association classificationQTQT variabilityQT variability indexQTVIQTVNRepolarizationSCDT wave alternansTWAU waveaction potential durationcardiovascularheart failureheart rate varianceimplantable cardioverter defibrillatorleft ventricular ejection fractionnormalized QT variabilitysudden cardiac death

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Area of Science:

  • Cardiology
  • Biomedical Engineering
  • Physiology

Background:

  • The QT Variability Index (QTVI) is a non-invasive metric assessing repolarization lability.
  • QTVI integrates QT interval variability and heart rate variability (HRV) to evaluate autonomic nervous system tone.
  • It analyzes beat-to-beat variations in QT and U wave duration from standard ECGs.

Purpose of the Study:

  • To review the existing literature on the QT Variability Index (QTVI).
  • To assess the application and predictive value of QTVI in cardiovascular disease.
  • To identify the need for prospective studies to determine the clinical utility of QTVI.

Main Methods:

  • Literature review of studies utilizing QTVI.
  • Analysis of QTVI's application in healthy individuals and cardiovascular patient cohorts.
  • Examination of studies assessing QTVI's predictive capability for adverse cardiovascular events.

Main Results:

  • Nineteen studies have reported QTVI data in healthy subjects; 20 in cardiovascular disease cohorts.
  • Six studies have investigated QTVI's role in predicting ventricular tachycardia/fibrillation (VT/VF), cardiac arrest, or death.
  • A significant body of evidence exists, but prospective trials are lacking.

Conclusions:

  • QTVI is a promising non-invasive measure of repolarization variability and autonomic function.
  • Current evidence suggests QTVI's potential in risk stratification for cardiovascular events.
  • Definitive determination of QTVI's clinical value requires prospective studies for therapy allocation.