BACKGROUND: The study of QT dispersion (QTd) is of increasing clinical interest, but there are very few data in large healthy populations. Furthermore, there is still discussion on the extent to which QTd reflects dispersion of measurement. This study addresses these problems. METHODS AND RESULTS: Twelve-lead ECGs recorded on 1501 apparently healthy adults and 1784 healthy neonates, infants, and children were used to derive normal limits of QTd and QT intervals by use of a fully automated approach. No age gradient or sex differences in QTd were seen and it was found that an upper limit of 50 ms was highly specific. Three-orthogonal-lead ECGs (n=1220) from the Common Standards for Quantitative Electrocardiography database were used to generate derived 12-lead ECGs, which had a significant increase in QTd of 10.1+/-13.1 ms compared with the original orthogonal-lead ECG but a mean difference of only 1.63+/-12.2 ms compared with the original 12-lead ECGs. In a population of 361 patients with old myocardial infarction, there was a statistically significant increase in mean QTd compared with that of the adult normal group (32.7+/-10.0 versus 24.53+/-8.2 ms; P<0. 0001). An estimate of computer measurement error was also obtained by creating 2 sets of 1220 ECGs from the original set of 1220. The mean error (difference in QTd on a paired basis) was found to be 0. 28+/-9.7 ms. CONCLUSIONS: These data indicate that QTd is age and sex independent, has a highly specific upper normal limit of 50 ms, is significantly lower in the 3-orthogonal-lead than in the 12-lead ECG, and is longer in patients with a previous myocardial infarction than in normal subjects.
BACKGROUND: The study of QT dispersion (QTd) is of increasing clinical interest, but there are very few data in large healthy populations. Furthermore, there is still discussion on the extent to which QTd reflects dispersion of measurement. This study addresses these problems. METHODS AND RESULTS: Twelve-lead ECGs recorded on 1501 apparently healthy adults and 1784 healthy neonates, infants, and children were used to derive normal limits of QTd and QT intervals by use of a fully automated approach. No age gradient or sex differences in QTd were seen and it was found that an upper limit of 50 ms was highly specific. Three-orthogonal-lead ECGs (n=1220) from the Common Standards for Quantitative Electrocardiography database were used to generate derived 12-lead ECGs, which had a significant increase in QTd of 10.1+/-13.1 ms compared with the original orthogonal-lead ECG but a mean difference of only 1.63+/-12.2 ms compared with the original 12-lead ECGs. In a population of 361 patients with old myocardial infarction, there was a statistically significant increase in mean QTd compared with that of the adult normal group (32.7+/-10.0 versus 24.53+/-8.2 ms; P<0. 0001). An estimate of computer measurement error was also obtained by creating 2 sets of 1220 ECGs from the original set of 1220. The mean error (difference in QTd on a paired basis) was found to be 0. 28+/-9.7 ms. CONCLUSIONS: These data indicate that QTd is age and sex independent, has a highly specific upper normal limit of 50 ms, is significantly lower in the 3-orthogonal-lead than in the 12-lead ECG, and is longer in patients with a previous myocardial infarction than in normal subjects.
Authors: Kaspar Lund; Juha S Perkiömäki; Christian Brohet; Hanne Elming; Mohammed Zaïdi; Christian Torp-Pedersen; Heikki V Huikuri; Hans Nygaard; Anders Kirstein Pedersen Journal: Ann Noninvasive Electrocardiol Date: 2002-01 Impact factor: 1.468
Authors: Milos Kesek; Anders Englund; Tomas Jernberg; Bo Lagerqvist; Bertil Lindahl Journal: Ann Noninvasive Electrocardiol Date: 2003-01 Impact factor: 1.468
Authors: Maria Shkolnikova; Svetlana Shalnova; Vladimir M Shkolnikov; Victoria Metelskaya; Alexander Deev; Evgueni Andreev; Dmitri Jdanov; James W Vaupel Journal: BMC Public Health Date: 2009-08-13 Impact factor: 3.295