Abstract 13906: Accentuated Morning Peak in Circadian Patterns of Acute Myocardial Infarction Onset in Patients with Increased Serum Triglyceride Levels
Background: It is well known that onset of acute myocardial infarction (AMI) shows characteristic circadian variations involving a definite morning peak and an indefinite nighttime peak. However, it is also reported that the bimodal peaks of AMI onset vary among subpopulations according to age, gender, and socioeconomic environments.
Methods: We investigated the factors that could affect circadian patterns of AMI onset in 7755 consecutive patients registered to the Osaka Acute Coronary Insufficiency Study (OACIS) between 1998 and 2009, whose time of AMI onset was definitely identified. A mixture of two von Mises distributions (VMD) was used to examine whether the pattern of AMI onset is unimodal or bimodal. The goodness of fit of VMD was assessed by likelihood ratio test and Akaike Information Criterion.
Results: Overall population had a circadian pattern of AMI onset with two peaks; a sharp morning peak (9:01 AM; 95%CI: 8:53-9:08 AM) and a less sharp nighttime peak (8:11 PM; 95%CI: 7:48-8:34 PM) (Figure, p<0.001). Serum triglyceride(TG) levels, smoking, age, initial TIMI flow, gender, working status had a statistically significant association with circadian patterns of AMI onset (p<0.001, p<0.001, p<0.001, p<0.001, p=0.010, p=0.048, respectively). Among them, serum TG levels had the largest influence on circadian pattern of AMI onset, whereas both HDL- and LDL-cholesterol levels did not. Population with TG≧150mg/dl had only one morning peak (8:47 AM; 95%CI: 8:36-8:58 AM) in circadian pattern of AMI onset (Figure), although all other subgroups had two peaks.
Conclusions: Circadian pattern of AMI onset had two peaks. Interestingly, serum TG levels might have strong relation with the morning peak of AMI onset rather than other factors, suggesting that individual life style could affect the onset pattern of AMI. Although confirmation in other cohorts is required, this finding may help identify triggers of AMI onset and guide subjects to prevent an onset of AMI.
- © 2012 by American Heart Association, Inc.