Adjusting QT Measurements for Heart Rate

QTc values are used in analysis of potential drug-induced QT interval prolongation, where the c stands for corrected for heart rate. Many correction factors have been developed to address this issue (see Camm et al. 2004). The more commonly used correction factors, QTcB (Bazett s correction) and QTcE (Eridericia s correction) 

7 The Proarrhythmic Cardiac Safety Regulatory Landscape Circa 2005-2015 

When discussing the history of the reasons behind the choice of the preferred formula for adjusting QT interval values, Camm and colleagues commented as follows (Camm et al. 2004, p 44)  

Bazett s correction is still the most commonly used correction factor in clinical practice most ECG machines used in clinical practice settings automatically provide this correction. 

Bazett s and Fridericia s corrections essentially aim to normalize the QT interval to a heart rate of 60 bpm. The nomenclature (and notation) used for these two corrections is as follows, where RR is the interval between the R wave of one ECG and the R wave of the subsequent ECG  

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