[Circadian variation of sudden cardiac death in young people with and without coronary disease].

Sudden cardiac death is not well known and provoking factors are yet mainly unknown. To clarify whether sudden cardiac death has a circadian rhythm in young people we have studied 40 patients < 45 years who died in Brescia between 1984 and 1993 of sudden cardiac death showing at autopsy features of coronary artery disease (CAD) and 12 patients aged < 30 years who died of sudden cardiac death without autoptic features of CAD. We observed a circadian rhythm in the hours of the morning in the two groups, more evident in patients without CAD. In patients with autoptic features of CAD, we also observed a higher rate of events during the winter months. We would like to stress the importance of the adrenergic system as a trigger able to produce the event. We believe that the role of the sympathetic nervous system is more important than other risk factors (for example platelet aggregability and blood viscosity) to precipitate sudden cardiac death, mainly because the circadian rhythm was more evident in patients without CAD. An increase of the data-base and a more detailed analysis of subgroups is necessary if we concretely want to prevent sudden cardiac death fitting antiarrhythmic therapy with circadian distribution of major events. We underline the practical impact of "chronorisk" together with the other cardiovascular risk factors.