Rautaharju and Dmitrienko formulae for QT interval correction
Various logarithmic and linear formulae for correction of QT interval has been discussed before. These include Bazett’s formula, Fridericia’s formula and Baseline correction for logarithmic correction and Framingham formula and Hodges formula for linear correction. Of these, Bazett’s and Fridericia’s were introduced in 1920 (exactly one century back!).
Rautaharju’s formula and Dmitrienko’s formula are two relatively recent formulae for correction of QT interval. The older formulae have problems with calculation of QTc during exercise. QTc using Bazett’s formula increased with exercise. Fridericia and Framingham formulae on the other hand showed a decrease in QTc with exercise. The results with Hodges formula was variable. But QTc calculated with Dmitrienko’s formula and Rautaharju’s formula were relatively constant despite increase in heart rate during exercise .
Rautaharju’s formula : QTc = QT * (120 + HR)/180
Dmitrienko’s formula : QTc = QT/RR0.413
Rautaharju’s formula has been shown to be better in predicting drug-induced torsade de pointes than Bazett’s formula .
A nomogram (Karjalainen QTc nomogram) for correction QT interval has also been suggested by Karjalainen J and colleagues (QTNc = QT + correcting number) .
Fridericia LS. The duration of systole in the electrocardiogram of normal subjects and of patients with heart disease. Acta Medica Scandinavica. 1920;53: 469-486.
Bazett HC. An analysis of the time-relations of electrocardiograms. Heart. 1920;7: 353–370.
Pentti M Rautaharju, Jay W Mason, Toshio Akiyama. New age- and sex-specific criteria for QT prolongation based on rate correction formulas that minimize bias at the upper normal limits. Int J Cardiol. 2014 Jul 1;174(3):535-40.
Dmitrienke AA, Sides GD, Winters KJ, et al. Electrocardiogram reference ranges derived from a standardized clinical trial population. Drug Inf J. 2005;39:395–405.
J Karjalainen, M Viitasalo, M Mänttäri, V Manninen. Relation between QT intervals and heart rates from 40 to 120 beats/min in rest electrocardiograms of men and a simple method to adjust QT interval values. J Am Coll Cardiol. 1994 Jun;23(7):1547-53.