An improved method to correct the QT interval of the electrocardiogram for changes in heart rate.

The adequacy of the Bazett formula to correct for heart rate-induced changes in the QT interval of the electrocardiogram has been frequently questioned. In the present study, a simple linear equation was derived, which in anesthetized dogs corrects more adequately for changes in heart rate than the Bazett formula. Regression analysis of experimental data yielded the following equation: QTc = QT - 0.087 (RR - 1000) = QT - 87 (60/HR - 1). The reliability of this equation was investigated in experiments on anesthetized dogs with different cardioactive drugs with a known mechanism of action.