Journal of electrocardiology
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Multicenter Study Comparative Study
A comparison of commonly used QT correction formulae: the effect of heart rate on the QTc of normal ECGs.
The corrected QT interval (QTc) is widely used in pharmaceutical studies and clinical practice. Bazett's QT correction formula is still the most popular, despite Simonson's warning in 1961 that it could not be recommended. Other QTc formulae, e.g. ⋯ Numerous references recommend 420 to 440 ms as the threshold for reporting prolonged QTc when using Bazett's formula. Based on this database, 30% of apparently normal ECGs would be reported as having abnormal QT intervals for the 440 ms threshold, or 10% if 460 ms is chosen, compared to <2% for the other formulae. It was also noted that QT has a linear trend with HR but not with RR.