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Circadian variation in cardiovascular events
1Adelaide and Meath Hospitals, Dublin, Ireland.
Insights
Cardiovascular events like heart attacks and strokes occur more frequently in the morning. Circadian rhythms influence these risks, highlighting the need for morning protection against cardiovascular disease.
Area of Science:
- Cardiology
- Chronobiology
- Physiology
Background:
- Prospective studies reveal a higher incidence of acute myocardial infarction, transient myocardial ischemia, unstable angina, sudden cardiac death, complex ventricular arrhythmias, and strokes during morning waking hours.
- Physiologic responses, including surges in blood pressure, heart rate, and catecholamine release upon waking, contribute to this circadian pattern of cardiovascular events.
Purpose of the Study:
- To investigate the temporal patterns of cardiovascular events.
- To understand the physiological mechanisms underlying the diurnal variation in cardiovascular disease.
- To inform clinical strategies for managing cardiovascular risk.
Main Methods:
- Analysis of prospective study data on cardiovascular event timing.
- Review of physiological studies on daily variations in cardiovascular parameters.
- Correlation of circadian rhythms with the incidence of cardiovascular events.
Main Results:
- A significantly greater incidence of acute myocardial infarction and other major cardiovascular events (e.g., stroke, sudden cardiac death) is observed in the morning hours.
- Physiological factors such as increased blood pressure, heart rate, and catecholamine release upon waking are associated with this morning peak in risk.
- Delaying daily activities does not eliminate but rather shifts the timing of cardiovascular risk.
Conclusions:
- Circadian variation significantly influences the timing of cardiovascular events, with a notable peak in the morning.
- Clinical strategies must incorporate protective measures for the morning hours to effectively manage cardiovascular disease risk.
- The use of long-acting therapeutic agents is an emerging approach to provide continuous protection, addressing the morning risk period.
Abstract:
Prospective studies have shown not only that there is a greater incidence of acute myocardial infarction during the morning waking hours but also that transient myocardial ischemia, unstable angina, sudden cardiac death, complex ventricular arrhythmieas, and strokes have a greater incidence at a similar time. Studies of the physiologic responses that occur throughout the day have shed much light on why such a pattern in the timing of cardiovascular events is seen. It has been shown, for example, that blood pressure and heart rate surge on waking and at the start of daily activities, as does release of catecholamine. It appears that delaying the time of arising and of commencing activities simply shifts the risk of cardiovascular events rather than negating it. The most important clinical message obtained from the study of circadian variation in cardiovascular disease is that protection should be offered to cover the morning waking hours in addition to other times of the day. This need is being addressed with the increasing use of long-acting therapeutic agents.