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Comparison of formulas for calculation of the corrected QT interval in infants and young children.

ABSTRACT: To compare 4 heart rate correction formulas for calculation of the rate corrected QT (QTc) interval among infants and young children.R-R and QT intervals were measured from digital electrocardiograms. QTc were calculated with the Bazett, Fridericia, Hodges, and Framingham formulas. QTc vs R-R graphs were plotted, and slopes of the regression lines compared. Slopes of QTc-R-R regression lines close to zero indicate consistent QT corrections over the range of heart rates.We reviewed electrocardiograms from 702 children, with 233 (33%) <1 year of age and 567 (81%) <2 years. The average heart rate was 122 ± 20 bpm (median 121 bpm). The slopes of the QTc-R-R regression lines for the 4 correction formulas were -0.019 (Bazett); 0.1028 (Fridericia); -0.1241 (Hodges); and 0.2748 (Framingham). With the Bazett formula, a QTc >460 ms was 2 SDs above the mean, compared with "prolonged" QTc values of 414, 443, and 353 ms for the Fridericia, Hodges, and Framingham formulas, respectively.The Bazett formula calculated the most consistent QTc; 460 ms is the best threshold for prolonged QTc. The study supports continued use of the Bazett formula for infants and children and differs from the use of the Fridericia correction during clinical trials of new medications.

SUBMITTER: Phan DQ

PROVIDER: S-EPMC4380641 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

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Comparison of formulas for calculation of the corrected QT interval in infants and young children.

Phan Derek Q DQ Silka Michael J MJ Lan Yueh-Tze YT Chang Ruey-Kang R RK

The Journal of pediatrics 20150131 4

<h4>Objective</h4>To compare 4 heart rate correction formulas for calculation of the rate corrected QT (QTc) interval among infants and young children.<h4>Study design</h4>R-R and QT intervals were measured from digital electrocardiograms. QTc were calculated with the Bazett, Fridericia, Hodges, and Framingham formulas. QTc vs R-R graphs were plotted, and slopes of the regression lines compared. Slopes of QTc-R-R regression lines close to zero indicate consistent QT corrections over the range of ...[more]

PMID: 25648293

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Project description:INTRODUCTION: In this study, we investigated the outcomes for patients with intentional organophosphate poisoning. Previous reports indicate that in contrast to normal heart rate-corrected QT intervals (QTc), QTc prolongation might be indicative of a poor prognosis for patients exposed to organophosphates. METHODS: We analyzed the records of 118 patients who were referred to Chang Gung Memorial Hospital for management of organophosphate poisoning between 2000 and 2011. Patients were grouped according to their initial QTc interval, i.e., normal (<0.44 s) or prolonged (>0.44 s). Demographic, clinical, laboratory, and mortality data were obtained for analysis. RESULTS: The incidence of hypotension in patients with prolonged QTc intervals was higher than that in the patients with normal QTc intervals (P?=?0.019). By the end of the study, 18 of 118 (15.2%) patients had died, including 3 of 75 (4.0%) patients with normal QTc intervals and 15 of 43 (34.9%) patients with prolonged QTc intervals. Using multivariate-Cox-regression analysis, we found that hypotension (OR?=?10.930, 95% CI?=?2.961-40.345, P?=?0.000), respiratory failure (OR?=?4.867, 95% CI?=?1.062-22.301, P?=?0.042), coma (OR?=?3.482, 95% CI?=?1.184-10.238, P?=?0.023), and QTc prolongation (OR?=?7.459, 95% CI?=?2.053-27.099, P?=?0.002) were significant risk factors for mortality. Furthermore, it was revealed that non-survivors not only had longer QTc interval (503.00±41.56 versus 432.71±51.21 ms, P?=?0.002), but also suffered higher incidences of hypotension (83.3 versus 12.0%, P?=?0.000), shortness of breath (64 versus 94.4%, P?=?0.010), bronchorrhea (55 versus 94.4%, P?=?0.002), bronchospasm (50.0 versus 94.4%, P?=?0.000), respiratory failure (94.4 versus 43.0%, P?=?0.000) and coma (66.7 versus 11.0%, P?=?0.000) than survivors. Finally, Kaplan-Meier analysis demonstrated that cumulative mortality was higher among patients with prolonged QTc intervals than among those with normal QTc intervals (Log-rank test, Chi-square test?=?20.36, P<0.001). CONCLUSIONS: QTc interval helps predict mortality after intentional organophosphate poisoning.

Dataset Information

Comparison of formulas for calculation of the corrected QT interval in infants and young children.

Publications

Comparison of formulas for calculation of the corrected QT interval in infants and young children.

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