November 1, 1998Pacing and Clinical Electrophysiology

QT Interval and QT Dispersion Measured with the Threshold Method Depend on Threshold Level

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Why the study?

Does the threshold level applied to the T wave differential affect the measured QT interval and QT dispersion in normal subjects and patients with hypertrophic cardiomyopathy?

Population

139 subjects, comprising 76 normal subjects and 63 patients with hypertrophic cardiomyopathy, contributing a…

Comparison

Computerized QT interval measurement using the… vs Comparison across 26 different threshold levels…

Design

Cross-sectional

Authors

VBVelislav N. BatchvarovElectrophysiology GYGang YiPeople's Bank of China XGXiaohua GuoGuangzhou Medical University

Discussion

Member takes

Implication

Threshold choice alters QTc by up to 70 ms in HCM; leaves open need for standardized ECG algorithms in research.

Structured PICO

Does the threshold level applied to the T wave differential affect the measured QT interval and QT dispersion in normal subjects and patients with hypertrophic cardiomyopathy?

Population

139 subjects, comprising 76 normal subjects and 63 patients with hypertrophic cardiomyopathy (HCM), contributing a total of 1,390 ECG recordings (10 consecutive recordings per individual).

Intervention

Computerized QT interval measurement using the threshold method applied to the first differential of the T wave, with threshold levels varied between 5% and 30% of the T wave maximum in 1% steps (26 different choices).

Comparator

Comparison across 26 different threshold levels (5% to 30%) and between normal subjects and HCM patients.

Outcome

Maximum QTc and QT dispersion (QTd, standard deviation of the QT in all 12 leads).surrogate

Computerized QT interval and dispersion measurements are highly dependent on the threshold level used, emphasizing the need to carefully examine and report algorithmic details in ECG studies.

Cite This Study

Batchvarov et al. (1998) studied this question.

synapsesocial.com/papers/6a8298d70de57fd8eeb28620 https://doi.org/10.1111/j.1540-8159.1998.tb01184.x

Topics

Hypertrophic cardiomyopathy

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QT Interval and QT Dispersion Measured with the Threshold Method Depend on Threshold Level

Discussion

Member takes

Implication

Structured PICO

Cite This Study

Topics

QT Interval and QT Dispersion Measured with the Threshold Method Depend on Threshold Level

Discussion

Member takes

Implication

Structured PICO

Cite This Study

Also Consider

Topics

Also Consider