Document Detail

Circadian variation of ambulatory myocardial ischemia. Triggering by daily activities and evidence for an endogenous circadian component.
MedLine Citation:
PMID:  8641025     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The morning peak in myocardial ischemia has been related to diurnal variations in physical and mental activities and to postural changes upon awakening. This study assesses (1) the effects of exogenous activity triggers at different times of the day and (2) the contribution of an endogenous (ie, activity- and posture-independent) circadian vulnerability for ambulatory ischemia.
METHODS AND RESULTS: Sixty-three stable coronary artery disease patients underwent ambulatory ECG monitoring and completed a structured diary assessing physical and mental activities. During 2519 hours of observation, a morning increase in ischemia coincided with increases in physical and mental activities, and an evening decrease in ischemia coincided with a decline in activities. During the morning, ischemic versus ischemia-free periods were more likely to occur with high levels of physical activity (P < .001). High physical activity triggered ischemia to a lesser but still significant extent (P < .05) in the afternoon but not in the evening (P = NS). High levels of mental activity triggered ischemia significantly during the morning (P < .04) and evening (P < .04) but not in the afternoon. When a residualized score procedure was used to correct ischemic time for each patient's simultaneously measured activities, for hourly heart rates, or for activity-related heart rate fluctuations, the circadian variation in ischemia was still observed (P < .001), with a peak at 6 AM. A significant increase in ischemia occurred immediately after awakening (P < .05), but activity-adjusted increases in morning ischemia persisted (P < .05) for 2 hours after awakening.
CONCLUSIONS: Exogenous factors (physical and mental activities) are most potent as triggers of ischemia during the morning hours, and the postural change after awakening contributes to the morning increase in ischemia. There is also evidence for an endogenous, activity-independent circadian influence on ischemic susceptibility that is independent of exogenous factors and that sustains the increase in ischemia upon awakening.
D S Krantz; W J Kop; F H Gabbay; A Rozanski; M Barnard; J Klein; Y Pardo; J S Gottdiener
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Circulation     Volume:  93     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  1996 Apr 
Date Detail:
Created Date:  1996-07-17     Completed Date:  1996-07-17     Revised Date:  2014-07-29    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1364-71     Citation Subset:  AIM; IM    
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MeSH Terms
Activities of Daily Living
Circadian Rhythm*
Electrocardiography, Ambulatory
Middle Aged
Motor Activity / physiology*
Myocardial Infarction / epidemiology*,  etiology,  physiopathology
Myocardial Ischemia / complications,  physiopathology
Records as Topic
Wakefulness / physiology
Grant Support

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