Related Experiment Videos
Circadian variation in the frequency of onset of acute myocardial infarction
Insights
Myocardial infarction (heart attack) shows a distinct daily pattern, peaking in the morning hours. This circadian rhythm in heart attack onset may be linked to thrombosis tendencies and is absent in patients on beta-blockers.
Area of Science:
- Cardiology
- Chronobiology
- Thrombosis Research
Background:
- Myocardial infarction (heart attack) is a leading cause of mortality worldwide.
- Understanding the temporal patterns of heart attack onset is crucial for prevention and treatment strategies.
- Previous studies suggest potential daily variations in cardiovascular events, but robust data on myocardial infarction timing is needed.
Purpose of the Study:
- To investigate whether the onset of myocardial infarction (heart attack) occurs randomly throughout the day.
- To identify a potential circadian rhythm in the frequency of myocardial infarction events.
- To explore the influence of beta-adrenergic blocking agents on this circadian pattern.
Main Methods:
- Analysis of the time of pain onset in 2999 patients admitted with myocardial infarction.
- Objective timing of myocardial infarction onset using plasma creatine kinase MB (CK-MB) levels in 703 patients.
- Comparison of circadian rhythmicity between patients receiving and not receiving beta-adrenergic blocking agents.
Main Results:
- A significant circadian rhythm in myocardial infarction onset was detected, with a peak frequency between 6 a.m. and noon.
- Objective CK-MB-estimated timing confirmed this circadian rhythm, showing a three-fold increase in onset frequency at the peak (9 a.m.) compared to the trough (11 p.m.).
- The circadian rhythm of myocardial infarction onset was absent in patients pre-treated with beta-adrenergic blocking agents but present in those without such therapy.
Conclusions:
- Myocardial infarction (heart attack) onset exhibits a marked circadian rhythm, suggesting non-random daily occurrence.
- The observed circadian timing may be related to daily variations in thrombotic tendency.
- Identifying and modifying the underlying rhythmic processes could offer new avenues for preventing myocardial infarction.
Abstract:
To determine whether the onset of myocardial infarction occurs randomly throughout the day, we analyzed the time of onset of pain in 2999 patients admitted with myocardial infarction. A marked circadian rhythm in the frequency of onset was detected, with a peak from 6 a.m. to noon (P less than 0.01). In 703 of the patients, the time of the first elevation in the plasma creatine kinase MB (CK-MB) level could be used to time the onset of myocardial infarction objectively. CK-MB-estimated timing confirmed the existence of a circadian rhythm, with a three-fold increase in the frequency of onset of myocardial infarction at peak (9 a.m.) as compared with trough (11 p.m.) periods. The circadian rhythm was not detected in patients receiving beta-adrenergic blocking agents before myocardial infarction but was present in those not receiving such therapy. If coronary arteries become vulnerable to occlusion when the intima covering an atherosclerotic plaque is disrupted, the circadian timing of myocardial infarction may result from a variation in the tendency to thrombosis. If the rhythmic processes that drive the circadian rhythm of myocardial-infarction onset can be identified, their modification may delay or prevent the occurrence of infarction.