Pacing and clinical electrophysiology : PACE
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Pacing Clin Electrophysiol · Sep 1999
Comparative StudyComparison of formulae for heart rate correction of QT interval in exercise electrocardiograms.
The study investigated the differences in five different formulae for heart rate correction of the QT interval in serial electrocardiograms recorded in healthy subjects subjected to graded exercise. Twenty-one healthy subjects (aged 37+/-10 years, 15 male) were subjected to graded physical exercise on a braked bicycle ergometer until the heart rate reached 120 beats/min. Digital electrocardiograms (ECG) were recorded on baseline and every 30 seconds during the exercise. ⋯ The differences obtained with the Fridericia formula were not statistically significant. The study shows that the practical meaning of QT, interval measurements depends on the correction formula used. In studies investigating repolarization changes (e.g., due to a new drug), the use of an ad-hoc selected heart rate correction formula is highly inappropriate because it may bias the results in either direction.