title: Ventricular repolarization dynamics during different sleep stages in the subacute phase of myocardial infarction.
abstract: BACKGROUND
  Ventricular arrhythmias after myocardial infarction (MI) are often nocturnal. However, the arrhythmogenic effects of sleep after MI are unknown. We examined the effects of sleep stages on QT dynamicity and tested the hypothesis of a differential effect of sleep stage on the QT/RR relationship after recent MI, versus in healthy controls (HC).
  
  
  METHODS
  Polysomnography and electrocardiograms were simultaneously recorded in 21 men in the subacute phase of a first uncomplicated MI, and in 10 age-matched, male HC. QT dynamicity (QT/RR slope) and parameters of QT interval were measured during wakefulness, stages 1-4 of nonrapid eye movement (non-REM) sleep, and REM sleep.
  
  
  RESULTS
  Mean QT and RR intervals increased through all sleep stages in both MI survivors and HC. The Bazett-corrected QT interval remained stable from wakefulness throughout all sleep stages. QT/RR slopes remained stable from wakefulness to stage 3 in both groups. However, unlike in MI survivors, the QT/RR slopes decreased and remained significantly lower during deep sleep and REM sleep in HC.
  
  
  CONCLUSIONS
  An abnormal QT/RR relationship in deep sleep and REM sleep was observed after a recent MI, reflecting an insufficient shortening of ventricular repolarization with increasing heart rates, which might have important implications in the nocturnal distribution of ventricular arrhythmias after MI.
authors.affiliation: Medizinische Klinik II, Universitätsklinikum Schleswig-Holstein Campus Lübeck, Lübeck, Germany. Bonnemei@medinf.mu-luebeck.de
authors.forename: Hendrik
authors.initials: H
authors.lastname: Bonnemeier
authors.forename: Jana K
authors.initials: JK
authors.lastname: Nötges
authors.forename: Benina
authors.initials: B
authors.lastname: Majunke
authors.forename: Alan
authors.initials: A
authors.lastname: Strassburg
authors.forename: Jasmin
authors.initials: J
authors.lastname: Ortak
authors.forename: Henning
authors.initials: H
authors.lastname: Kothe
authors.forename: Gunther
authors.initials: G
authors.lastname: Weitz
authors.forename: Heribert
authors.initials: H
authors.lastname: Schunkert
mesh_terms: D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D016022:Case-Control Studies; D004562:Electrocardiography; D006339:Heart Rate; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology*; D017286:Polysomnography; D012894:Sleep Stages / Q000502:physiology*