1. An ECG system for monitoring QT interval information comprising: a source of ECG signal information; a QT interval processor responsive to ECG signal information which operates to periodically produce QT interval information; a storage device responsive to the QT interval processor which stores QT interval information as a function of time; a trend processor, responsive to QT interval information which operates to calculate a trend of QT information over a period of time, wherein the QT interval information which is trended further includes one or more of the QT interval, QTc values, and dQTc values; a QT interval correction processor which produces the QTc values corrected for a patient heart rate; a QT interval variation processor which produces dQTc values relative to a baseline QTc value; a display responsive to the trend processor and operable to display a trend of QT information over the period of time; and a user control operable to select the period of time over which the trend of QT information is displayed.