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Recent heart rate history affects QT interval duration in atrial fibrillation.

ABSTRACT: QT interval prolongation is associated with a risk of polymorphic ventricular tachycardia. QT interval shortens with increasing heart rate and correction for this effect is necessary for meaningful QT interval assessment. We aim to improve current methods of correcting the QT interval during atrial fibrillation (AF). Digitized Holter recordings were analyzed from patients with AF. Models of QT interval dependence on RR intervals were tested by sorting the beats into 20 bins based on corrected RR interval and assessing ST-T variability within the bins. Signal-averaging within bins was performed to determine QT/RR dependence. Data from 30 patients (29 men, 69.3±7.3 years) were evaluated. QT behavior in AF is well described by a linear function (slope ~0.19) of steady-state corrected RR interval. Corrected RR is calculated as a combination of an exponential weight function with time-constant of 2 minutes and a smaller "immediate response" component (weight ~ 0.18). This model performs significantly (p<0.0001) better than models based on instantaneous RR interval only including Bazett and Fridericia. It also outperforms models based on shorter time-constants and other previously proposed models. This model may improve detection of repolarization delay in AF. QT response to heart rate changes in AF is similar to previously published QT dynamics during atrial pacing and in sinus rhythm.

SUBMITTER: Riad FS

PROVIDER: S-EPMC5342318 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Recent heart rate history affects QT interval duration in atrial fibrillation.

Riad Fady S FS Razak Eathar E Saba Samir S Shalaby Alaa A Nemec Jan J

PloS one 20170308 3

QT interval prolongation is associated with a risk of polymorphic ventricular tachycardia. QT interval shortens with increasing heart rate and correction for this effect is necessary for meaningful QT interval assessment. We aim to improve current methods of correcting the QT interval during atrial fibrillation (AF). Digitized Holter recordings were analyzed from patients with AF. Models of QT interval dependence on RR intervals were tested by sorting the beats into 20 bins based on corrected RR ...[more]

PMID: 28273109

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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.

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Recent heart rate history affects QT interval duration in atrial fibrillation.

Publications

Recent heart rate history affects QT interval duration in atrial fibrillation.

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