We investigated whether automatic QT dispersion measurements are more discriminating than manual measurement in three clinical groups: myocardial infarction; arrhythmia; normals. Four automatic techniques of QT interval measurement, based on models of T wave shape, were used: i) intersection of maximum slope of T wave with baseline (QTsi), ii) intersection of linear best fit over the region 30% to 70% of peak T wave amplitude with baseline (QT30/70), iii) intersection of linear best fit over the region 10% to 30% of peak T wave amplitude (QT10/30) with baseline, and iv) minimum/maximum of 2nd order polynomial best fit over a 0.1 s interval commencing at 50% peak amplitude (QT2nd).
There were no significant differences between dispersion in the groups when measured manually. There were significant differences between normal and infarct groups for all automatic techniques (p < 0.05), and between normal and arrhythmia groups for QT30/70 and QT2nd (p<0.05). Automatic techniques were better able to discriminate between normal and cardiac patient groups.
Langley P, Murray A. Comparison of manual and automatic QT dispersion measurements in clinical groups. Computers in Cardiology 2001;28:645-8.
Dr. Philip Langley, Freeman Unit, Newcastle upon Tyne. Tel: +44 (0)191-223-6161.
Regional Medical Physics Department, Freeman Hospital, Newcastle upon Tyne, NE7 7DN, UK.
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