QT variability index

Craig P. Dobson, Andrew Kim, Mark Haigney*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


The QT Variability Index (QTVI) is a non-invasive measure of repolarization lability that has been applied to a wide variety of subjects with cardiovascular disease. It is a ratio of normalized QT variability to normalized heart rate variability, and therefore includes an assessment of autonomic nervous system tone. The approach assesses beat-to-beat variability in the duration of the QT and U wave in conventional surface electrocardiographic recordings, as well as determines the heart rate variability (HRV) from the same recording. As opposed to T wave alternans, QTVI assesses variance in repolarization at all frequencies. Nineteen studies have published data on QTVI in healthy individuals, while 20 have evaluated its performance in cohorts with cardiovascular disease. Six studies have assessed the utility of QTVI in predicting VT/VF, cardiac arrest, or cardiovascular death. A prospective study utilizing QTVI to determine therapy allocation has not been performed, and therefore the final determination of the value of the metric awaits definitive exploration.

Original languageEnglish
Pages (from-to)186-194
Number of pages9
JournalProgress in Cardiovascular Diseases
Issue number2
StatePublished - Sep 2013
Externally publishedYes


  • Cardiovascular mortality
  • Heart failure
  • QT
  • QT variability
  • Repolarization
  • U wave


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