AIMS: The @entity1162 is mainly defined by QT interval prolongation (QTc > 0.44s). However, data obtained in genotyped @entity1 showed that resting QTc measurement alone may be inaccurate for ascertaining the phenotype. The aim of this study was to evaluate the diagnostic performance of QT interval rate-dependence in untreated chromosome 11-linked @entity1 . METHODS: The study population consisted of 25 untreated long QT @entity1 linked to chromosome 11 and 25 age- and gender-matched controls. QTc intervals were measured on 12-lead resting ECG recordings. From 24-h Holter recordings, the slope of the relationship between ventricular repolarization and heart rate was studied separately day and night to assess neural modulation. Mean heart rates and rate-dependences of QT and Q-maximum of T (QTm) intervals were compared between long QT @entity1 and controls for both time periods. RESULTS: In both groups, the rate-dependences were modulated by day-night influences. When compared to controls, long QT @entity1 showed a significant increase at night in QT/RR slopes (0.158 +/- 0.05 vs 0.117 +/- 0.03, P = 0.002) and QTm/RR slopes (0.163 +/- 0.05 vs 0.116 +/- 0.04, P = 0.0006). Multivariate analysis, adjusting QTc interval on age and gender, discriminated between long QT @entity1 and controls with a 76% sensitivity and a 84% specificity. A 96% sensitivity and a 96% specificity were reached by taking into account the QTm/RR slope at night, the QTc interval and the mean heart rate during the day. CONCLUSION: QT interval variables obtained from 24-h ECG recordings improve @entity1162 diagnosis by showing an increased nocturnal ventricular repolarization rate-dependence in genotyped chromosome 11-linked @entity1 .

Diagnostic performance of QT interval variables from 24-h electrocardiography in the XXXX .

@entity1 :: ('9606', 'Species') :: ['patients'] @entity1162 :: ('MESH:D008133', 'Disease') :: ['long QT syndrome']
@entity1162 :: (MESH:D008133,Disease) :: ['long QT syndrome']
