QT interval prolongation in future SIDS victims: a polysomnographic study.
OBJECTIVE
Previous data have suggested that a prolonged QTc interval during the first days of life can be associated with some cases of sudden infant death syndrome (SIDS). Analysis of heart rate variability during sleep in future SIDS victims has shown findings compatible with an imbalance in autonomic tone. We hypothesized that some future SIDS infants could have longer QTc intervals during sleep, compared with healthy control infants, and that this difference would correlate with the autonomic imbalance already found in these infants.


METHODS
QTc intervals and a heart rate autoregressive power spectral analysis were calculated during the same periods in the polysomnographic sleep recordings of 18 infants who eventually died of SIDS and of 18 control infants. The control infants were matched for sex, gestational age, postnatal age, birth weight, and sleep position. The median postnatal age was 8 weeks.


RESULTS
Compared with control infants, future SIDS victims were characterized by having longer QTc intervals during total sleep (P = 0.019), rapid eye movement sleep (P = 0.045) and non-rapid eye movement sleep (P = 0.029). When the night was divided into 3 equal parts, this difference was always present but was most marked during the last part of the night. There was, respectively, a negative and a positive correlation between parasympathetic activity and sympathovagal balance and median and maximum QTc interval values.


CONCLUSIONS
Compared with QTc intervals in matched control infants, QTc intervals were increased in future SIDS victims. Such a prolongation could be related to the autonomic dysfunction already reported in these patients.
Franco
Patricia
P
Pediatric Sleep Unit, Hôpital M&re-Enfant & INSERM-U628, University Lyon, Lyon, France. pfranco@univ-lyon1.fr
Groswasser
José
J
Scaillet
Sonia
S
Lanquart
Jean-Pol
JP
Benatar
Abraham
A
Sastre
Jean-Pierre
JP
Chevalier
Philippe
P
Kugener
Béatrice
B
Kahn
André
A
Lin
Jian-Sheng
JS
D001341:Autonomic Nervous System / Q000503:physiopathology; D001530:Belgium; D004562:Electrocardiography; D005260:Female; D005583:Fourier Analysis; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007223:Infant; D008133:Long QT Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D017286:Polysomnography; D012307:Risk Factors; D012815:Signal Processing, Computer-Assisted; D013398:Sudden Infant Death / Q000175:diagnosis / Q000209:etiology*