An analysis of the electrocardiogram QT interval

Brazilian Journal of Medical and Biological Research

N.r. Koehler¹  J.p. Zouvi¹  L.a. Acevedo¹  B.j. Sukienik¹  M. Rabin¹ 

[1] ,Pontifícia Universidade Católica Faculdade de Medicina and Hospital São Lucas Departamento de Clínica MédicaPorto Alegre RS ,Brasil

关键词: Electrocardiography;    Long QT syndrome;    Arrhythmia;    QT interval;   

DOI  :  10.1590/S0100-879X2004000100004

来源: SciELO

【 摘 要 】

No reports testing the efficacy of the use of the QT/RR ratio <1/2 for detecting a normal QTc interval were found in the literature. The objective of the present study was to determine if a QT/RR ratio <=1/2 can be considered to be equal to the normal QTc and to compare the QT and QTc measured and calculated clinically and by a computerized electrocardiograph. Ratios (140 QT/RR) of 28 successive electrocardiograms obtained from 28 consecutive patients in a tertiary level teaching hospital were analyzed clinically by 5 independent observers and by a computerized electrocardiograph. The QT/RR ratio provided 56% sensitivity and 78% specificity, with an area under the receiver operator characteristic curve of 75.8% (95%CI: 0.68 to 0.84). The divergence in QT and QTc interval measurements between clinical and computerized evaluation were 0.01 ± 0.03 s (95%CI: 0.04-0.02) and 0.01 ± 0.04 s (95%CI: -0.05-0.03), respectively. The QT and QTc values measured clinically and by a computerized electrocardiograph were similar. The QT/RR ratio <=1/2 was not a satisfactory index for QTc evaluation because it could not predict a normal QTc value.

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