Effect of Age and Gender on Heart Rate Correction Factor for the QT Interval

概要

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Objective: To assess the influence of age and gender on QT/RR regression factor, which is used for correcting QT interval for the effect of heart rate. Methods: Baseline digital ECGs of 4372 healthy normal subjects—846 children (age: 6–18 yrs; 596 males/250 females) and 3526 adults (age 19–80 yrs; 2100 males/1426 females) were read in a central ECG laboratory using onscreen digital calipers for QT/RR intervals. Age-specific exponential factors for QT correction in different age groups were determined using QTc/RR regression plots for males and females. The derived QTc formulae were compared with the formulae by Bazett and Fridericia comparing the QTc/RR correlation trend line. Results: Exponential factor for QT correction in 6–12 yrs group was 0.357, 13–19 yrs group was 0.341, 20–29 yrs group was 0.325, 30–39 yrs group was 0.336, 40–49 yrs group was 0.389, 50–59 yrs group was 0.431, 60–69 yrs group was 0.451, 70 yrs and above group was 0.427. QTc by Bazett overcorrects for the effect of heart rate in paediatric population. Conclusion: QT correction factors for children are closer to QT correction by Fridericias than Bazett. QT correction factor was similar in boys and girls till age of 13 yrs; it was greater in females thereafter. At all heart rates, Fridericia and age-specific formulae perform better than the Bazett formula. These findings have implications for assessing the long QT syndrome.