Intra- and interreader variability in QT interval measurement by tangent and threshold methods in a central electrocardiogram laboratory

Panicker, Gopi Krishna; Karnad, Dilip R.; Natekar, Mili; Kothari, Snehal; Narula, Dhiraj; Lokhandwala, Yash

doi:10.1016/j.jelectrocard.2009.01.003

Cited by 47 publications

(35 citation statements)

References 14 publications

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“…Comparing the mean QT values obtained with tangential (282 Ϯ 39) and threshold (291 Ϯ 42) methods by paired t test, we found a statistically significant difference (Ϫ9.1 Ϯ 14; p ϭ 0.0001), however, with an excellent agreement between the 2 methods (Pearson correlation coefficient [r] ϭ 0.94). It is already known that the first method slightly underestimates the QT interval; however, it has a similar or higher reproducibility (17); moreover, we consider it particularly appropriate in SQT patients because of the high-voltage T waves.…”

Section: Methodsmentioning

confidence: 89%

Long-Term Follow-Up of Patients With Short QT Syndrome

Giustetto

Schimpf

Mazzanti

et al. 2011

Journal of the American College of Cardiology

286

211

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Section: Methodsmentioning

confidence: 89%

Long-Term Follow-Up of Patients With Short QT Syndrome

Giustetto

Schimpf

Mazzanti

et al. 2011

Journal of the American College of Cardiology

286

211

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“…the point between the T and U wave which is closest to the baseline) to determine the end of the T-wave [35]. This seems to result in slightly longer QT intervals [36], but further studies are underway.…”

Section: Qt Problem 3: Where Does Qt End?mentioning

confidence: 99%

The Measurement of the QT Interval

Postema¹,

Wilde

2014

CCR

257

211

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The evaluation of every electrocardiogram should also include an effort to interpret the QT interval to assess the risk of malignant arrhythmias and sudden death associated with an aberrant QT interval. The QT interval is measured from the beginning of the QRS complex to the end of the T-wave, and should be corrected for heart rate to enable comparison with reference values. However, the correct determination of the QT interval, and its value, appears to be a daunting task. Although computerized analysis and interpretation of the QT interval are widely available, these might well over- or underestimate the QT interval and may thus either result in unnecessary treatment or preclude appropriate measures to be taken. This is particularly evident with difficult T-wave morphologies and technically suboptimal ECGs. Similarly, also accurate manual assessment of the QT interval appears to be difficult for many physicians worldwide. In this review we delineate the history of the measurement of the QT interval, its underlying pathophysiological mechanisms and the current standards of the measurement of the QT interval, we provide a glimpse into the future and we discuss several issues troubling accurate measurement of the QT interval. These issues include the lead choice, U-waves, determination of the end of the T-wave, different heart rate correction formulas, arrhythmias and the definition of normal and aberrant QT intervals. Furthermore, we provide recommendations that may serve as guidance to address these complexities and which support accurate assessment of the QT interval and its interpretation.

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“…19 QT interval and T p T e were defined as interval between QRS onset and T e , and between T p and T e in a single lead. We additionally determined T p T e _total in BS-ECG as interval between earliest T peak in any lead and last T end in any lead.…”

Section: Downloaded Frommentioning

confidence: 99%

Electrocardiographic T Wave and its Relation With Ventricular Repolarization Along Major Anatomical Axes

Meijborg

Conrath

Opthof

et al. 2014

Circ: Arrhythmia and Electrophysiology

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Background— The genesis of the electrocardiographic T wave is incompletely understood and subject to controversy. We have correlated the ventricular repolarization sequence with simultaneously recorded T waves. Methods and Results— Nine pig hearts were Langendorff-perfused (atrial pacing, cycle length 650 ms). Local activation and repolarization times were derived from unipolar electrograms sampling the ventricular myocardium. Dispersion of repolarization time was determined along 4 anatomic axes: left ventricle (LV)–right ventricle (RV), LV:apico-basal, LV:anterior-posterior, and LV:transmural. The heart was immersed in a fluid-filled bucket containing 61 electrodes to determine T p (T peak in lead of maximum integral), T p T e (T p to T end ), and T p T e _total (first T peak in any lead to last T end in any lead). Repolarization was nonlinearly distributed in time. RT 25 (time at which 25% of sites were repolarized, 288±26 ms) concurred with T p . T p T e was 38±8 ms, and T p T e _total was 75±9 ms. T p T e _total correlated with dispersion of repolarization time in the entire heart (73±18 ms), but not with dispersion of repolarization times along individual axes (LV–RV, 66±17 ms; LV:apico-basal, 51±18 ms; LV:anterior-posterior, 51±27 ms; mean LV:transmural, 14±7 ms; all n=9). Conclusions— We provide a correlation between local repolarization and T wave in a pseudo-ECG. Repolarization differences along all anatomic axes contribute to the T wave. T p T e _total represents total dispersion of repolarization. At T p , ≈25% of ventricular sites have been repolarized.

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Intra- and interreader variability in QT interval measurement by tangent and threshold methods in a central electrocardiogram laboratory

Cited by 47 publications

References 14 publications

Long-Term Follow-Up of Patients With Short QT Syndrome

Long-Term Follow-Up of Patients With Short QT Syndrome

The Measurement of the QT Interval

Electrocardiographic T Wave and its Relation With Ventricular Repolarization Along Major Anatomical Axes

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