From a Static to a Dynamic Concept of Risk: the Orcadian Epidemiology of Cardiovascular Events

Abstract

A growing body of evidence substantiates that the occurrence of cardiovascular events is unevenly distributed in time, especially during the 24h. These temporal patterns are indicative of temporal variation in the (1) pathophysiological mechanisms that trigger cardiovascular events and (2) physiological status of the cardiovascular system, which combine to give rise to 24h and other periodicities in the susceptibility to disease. The classic assumption of epidemiologic studies is constancy (or homeostasis) in one's risk to disease during the 24h, as well as other, time domains. However, we propose a new concept, that of chronorisk since it takes into account the temporal variability in the pathophysiological mechanisms and their reciprocal temporal interactions that lead to day-night and other time-dependent patterns in cardiovascular events. This chronobiological approach, which is expected to contribute new insight into the prognostic and therapeutic assessment of cardiovascular events, is worthy of broader application in cardiovascular and other fields of medicine and warrants further investigation.

Key Words:

• Arrhythmia
• Blood pressure
• Orcadian Rhythm
• Hemorrhage
• Myocardial infarction
• Myocardial ischemia
• Risk factors
• Stroke
• Sudden cardiac death
• Thrombosis
• Time factors