Diurnal, weekly and seasonal variation of sudden death - Population-based analysis of 24 061 consecutive cases

Aims Several studies have reported circadian and seasonal variations in acu te cardiovascular disease. In addition, a weekly variation has been observe d in acute myocardial infarction. The aim of our study was to determine the circadian weekly, and seasonal variations of sudden death utilizing popula tion-based data. Methods and Results We analysed the emergency medical system data of Berlin (West) from 1987-1991 with respect to all consecutive sudden deaths in sub jects >18 years (n=24 061). There was a marked circadian variation of sudde n death, with a minimum between 0 and 6 h and a maximum between 6 and 12 h (P<0.0001) for every day of the week. A minimum of events occurred on Sunda ys (n=3143), and a maximum on Mondays (n=3721), corresponding to a relative increase of 18.3% (P<0.0001). The increase was more pronounced (23.6%) in patients less than or equal to 65 than in patients >65 (15.7%). In addition , we found a significant seasonal variation (P<0.0001) in events, with a ma ximum during winter (December to February, n = 6493), and a minimum during summer (June to August, n = 5472), corresponding to a relative difference o f 18.7%. The seasonal variation was more pronounced in patients >65 years. Conclusion The present analyses demonstrate marked variations in the occurr ence of sudden death with peaks during morning hours, on Mondays, and durin g winter months. The findings suggest that the onset of sudden death may be associated with endogenous rhythms and external factors including climatic conditions. (C) 2000 The European Society of Cardiology.