A comparison of the four most commonly used formulas to adjust the QT-interval for heart rate in 22000 healthy subjects

Purpose The QT interval on an ECG is influenced by heart rate, requiring correction formulas for adjusted QT (QTc) values. In daily clinical practice, Bazett's formula is the most commonly used, while the FDA recommends Fridericia's formula for drug development. Other commonly used formulas include Framingham and Hodges. This study compared the accuracy of these four frequently used formulas in correcting the QT interval for heart rate. Methods 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 and body mass index. Results The study analyzed 16,170 males and 5,893 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) formulas 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 formulas in both sexes (P < 0.05). Conclusion In apparently healthy individuals, the Fridericia formula is the most reliable method for correcting the QT interval for heart rate, and we recommend its use in studies involving heathy subjects.