The QT interval on an ECG is influenced by heart rate, requiring correction formulae for adjusted QT (QTc) values. In daily clinical practice, Bazett's formula is the most commonly used; however, the FDA generally recommends Fridericia's formula for drug development, aside from exceptional circumstances. Other commonly used formulae include Framingham and Hodges. This study compared the accuracy of these four frequently used formulae in correcting the QT interval for heart rate. We retrospectively assessed ECGs from 22,063 medically assessed healthy individuals who participated in phase 1 trials between 1997 and 2023. Pearson correlation coefficient (r) between QTc and heart rate (HR) and the linear regression slope (b) were calculated for each formula and the influence of age, sex body mass index and heart rate. The study analyzed 16,170 males and 5893 females (mean age: 34.9 ± 15.3 years) to assess QTc-heart rate (HR) correlations. The Fridericia formula showed the strongest reliability, with the lowest correlation (r = 0.018) and a nearly horizontal regression slope (b = 0.04). The Hodges (r = -0.182, b = -0.39) and Framingham (r = 0.200, b = 0.43) formulae followed. The Bazett formula performed worst (r = 0.483, b = 1.12). Fridericia remained the most accurate across subgroups except in low BMI groups and differed significantly from other formulae in both sexes (P < 0.05). In apparently healthy individuals, Fridericia formula is the most reliable method for correcting the QT interval for heart rate and we recommend its use in studies involving healthy subjects.
Hoek et al. (Fri,) studied this question.
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