The QT variability index and cardiac autonomic modulation: perspectives from apparently healthy @entity1 with XXXX .

@entity1 @entity1688 @entity1162 @entity1566 @entity451 @entity258 @entity65
OBJECTIVE: To describe the effect of @entity1566 ( @entity1566 ) on the QT variability index (QTVI). METHODS: Digital electrocardiograms from 113 age-matched @entity1 (40 with @entity1688 , 26 with high @entity451 , 17 @entity258 and 31 controls) were analyzed. RR interval, heart rate (HR) variability [total power (TP(RR)), low frequency (LF(RR)) and high frequency (HF(RR))], QT interval duration, Bazett HR-corrected QT (QTc), @entity1162 ( @entity1162 ) and QTVI were compared. RESULTS: Significant group main effects were present for RR, QTc, TP(RR) and LF(RR), but not QT duration, @entity1162 or HF(RR). Post hoc comparisons revealed the following: (1) longer RR in controls versus subjects with high @entity451 and @entity258 , and in subjects with @entity1688 versus high @entity451 and @entity258 ; (2) QTc was longer in subjects with @entity258 versus controls and shorter in subjects with @entity1688 versus high @entity451 , and (3) TP(RR) and LF(RR) were different in controls and subjects with high @entity451 compared to those with @entity258 . QTVI was significantly elevated in all @entity1566 groups compared to controls. Significant negative correlations between QTVI and HF(RR) were observed in all @entity1566 groups, and TP(RR) and LF(RR) in subjects with @entity1688 and high @entity451 only. Age was negatively correlated in controls. CONCLUSIONS: QTVI is negatively affected in otherwise healthy @entity1566 @entity1 compared to age-matched controls. This observation appears to reflect the attenuation of vagal modulation, sympathetic impairment above the sixth thoracic vertebra and/or a heightened degree of @entity65 risk.
