Ventricular repolarization dynamics during different sleep stages in the subacute phase of myocardial infarction.
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.
Bonnemeier
Hendrik
H
Medizinische Klinik II, Universitätsklinikum Schleswig-Holstein Campus Lübeck, Lübeck, Germany. Bonnemei@medinf.mu-luebeck.de
Nötges
Jana K
JK
Majunke
Benina
B
Strassburg
Alan
A
Ortak
Jasmin
J
Kothe
Henning
H
Weitz
Gunther
G
Schunkert
Heribert
H
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*