Cited by 312Cardiac electrophysiology and arrhythmiasHeart Rate Variability and Autonomic ControlECG Monitoring and Analysis

Diurnal pattern of QTc interval: How long is prolonged?

Open access
Molnar, Janos, Zhang, Feng, Weiss, Jerry, Ehlert, Frederick A., Rosenthal, James E.·1996·Journal of the American College of Cardiology

Abstract

Objectives This study sought to evaluate the range and variability of the QT and corrected QT (QTc) intervals over 24 h and to assess their pattern and relation to heart rate variability.Background Recent Holter monitoring data have revealed a high degree of daily variability in the QTc interval. The pattern of this variability and its relation to heart rate variability remain poorly characterized.Methods We developed and validated a new method for continuous measurement of QT intervals from three-channel, 24-h Holter recordings. Average RR, QT, QTc and heart rate variability were measured from 5-min segments of data from 21 healthy subjects.Results Measurement of 6,048 segments showed mean (+/- SD) RR, QT and QTc intervals of 830 +/- 100, 407 +/- 23 and 445 +/- 16 ms, respectively (mean QTc interval for men 434 +/- 12 ms, 457 +/- 10 ms for women, p < 0.0001). The average maximal QTc interval was 495 +/- 21 ms and the average QTc range 95 +/- 20 ms. The maximal QTc interval was > or = 500 ms in 6 subjects and > or = 490 ms in 13. The 95% upper confidence limit for the mean 24-h QTc interval was 452 ms (men 439 ms, women 461 ms). The RR, QT and QTc intervals and the high frequency component of heart rate variability were greater during sleep. Both the QTc interval and the variability between hourly minimal and maximal QTc intervals reached their circadian peak shortly after awakening, before declining to daytime levels.Conclusions The maximal QTc interval over 24 h in normal subjects is longer than heretofore thought. Both QT and QTc intervals are longer during sleep. The QTc interval and QTc variability reach a peak shortly after awakening, which may reflect increased autonomic instability during early waking hours, and the time of the peak value corresponds in time to the period of reported increased vulnerability to ventricular tachycardia and sudden cardiac death. These findings have implications regarding the definition of QT prolongation and its use in predicting arrhythmias and sudden death.

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Integrity signals

Registry

Crossref · 10.1016/0735-1097(95)00426-2

Cites

47 of 47 references verified0 citation errors · 0 not checkable

Statistics

Claims the paper makes

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

The self-check needs the paper’s full text.

Cites

Flagged first, then by citations

2 of the 49 references couldn’t be matched to a known paper.

Research works printed but not linked: 4

  1. Lepeschkin E. Modern Electrocardiography. Vol. 1. Baltimore: Williams & Wilkins, 1951:180-8.
  2. II. Bazett HC. An analysis of time-relations of the electrocardiogram. Heart 1920;7:353-70.
  3. Hegglin R, Holtzmann M. Die Klinische Bedeutung des Verlangerter- Distanz (Systolendauer) in Electrokardiogram. Z Klin Med 1937;132:1-32.
  4. Molnar J, Zhang F, Weiss JS, Rosenthal J. Why not Bazett's? Evaluation of 5 QT correction formulas using a new software assisted method of contin- uous QT measurement from 24-hour Holter recordings [abstract]. PACE 1995;18:852.

Cited by

Sorted by citations

Authors
Molnar, J., Zhang, F., Weiss, J., Ehlert, F. A., & Rosenthal, J. E.
Affiliations
Northwestern University (US)
Corresponding author
Rosenthal, James E.
Venue
Journal of the American College of Cardiology
Publisher
Elsevier BV
Published
1996-01
Volume
27
Issue
1
Pages
76-83
ISSN
0735-1097 (ISSN-L)
OpenAlex
W160020775
Cited by
312
References
49
Citations by year
2026: 3 · 2025: 5 · 2024: 4 · 2023: 6 · 2022: 3 · 2021: 8 · 2020: 6 · 2019: 4 · 2018: 8 · 2017: 12 · 2016: 5 · 2015: 8 · 2014: 17 · 2013: 18 · 2012: 11
FWCI
12.44
Type
journal article
Language
en
Open access
Locations
  • Journal of the American College of Cardiology (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Cardiac electrophysiology and arrhythmias
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Heart Rate Variability and Autonomic Control
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › ECG Monitoring and Analysis
Keywords
QTc interval, diurnal variation, circadian rhythm, heart rate variability, QT prolongation, sleep, awakening, autonomic instability, sudden cardiac death, ventricular tachycardia, Holter monitoring, QT interval measurement
MeSH terms
Adult, Aged, Circadian Rhythm, Diagnosis, Computer-Assisted, Female, Heart Conduction System, Heart Rate, Humans, Male, Middle Aged, Reference Values, Reproducibility of Results, Observer Variation, Electrocardiography, Ambulatory, Linear Models, Least-Squares Analysis, Sex Distribution

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review