[Circadian patterns of ischemic events]

These is evidence of circadian variations in the occurrence of ischemic events such as: silent myocardial ischemia, stable angina, instable angina, acute myocardial infarction, sustained ventricular tachycardia, cerebral infarction, transient ischemic attack (TIA) and sudden cardiac death. In the general population many cardiovascular disorders occur with the greatest frequency between 6 and 12 a.m. (i.e. after awakening). Blood pressure, too, follows a distinct circadian pattern. Factors affecting circadian variations in cardiovascular disorders include physiological determinants, such as heart rate, catecholamine release, and platelet aggregation-which themselves cyclically vary-, and exogenous factors such as mental stress, anxiety, and physical activity. In chronotherapy, circadian variations in disease states and in the pharmacodynamic properties of drugs are exploited to improve prevention and treatment. Characterization of diseases states with this approach allows more accurate determination of the times when patients are at highest risk and therefore in greatest need of preventive measures; it also provides a mechanism for designing optimal drug regimens. In this review we therefore describe recent findings about the effects of biorhythms on cardiovascular disorders and their implications for optimal drug therapy.