The heart rate-corrected QT interval (QTc) is the traditional measurement for assessing the duration of ventricular repolarization.
However when QRS duration is increased (which contributes to QT prolongation), the utility of QTc is limited. In these cases, it has been proposed that the JT interval is a more appropriate measure of ventricular repolarization than the QT. JTc is defined as the corrected JT interval. It is calculated as QTc minus QRS Duration (JTc = QTc - QRS duration).
NOTE: QTc is the QT interval corrected for Heart Rate, and there are various proposed methods to include the RR interval to calculate QTc. Common methods of calculating QTc use Fridericia or Bazett formulas (included in the ECG Analysis Module).