Abstract 11430: Lower Framingham Risk Score and Less Calcium Channel Blocker Use are Associated with Morning Peak in the Circadian Variation of Acute Coronary Syndrome Onset
Introduction A circadian variation in the frequency of the onset of acute coronary syndrome (ACS) has been well described. However, there are few studies analyzing the influences of coronary risk factors and anti-hypertensive medications on the circadian variation of ACS.
Hypothesis We assessed the hypothesis that coronary risk factors and anti-hypertensive medications could be associated with circadian variation of ACS.
Methods and Results Five hundred and sixty patients were admitted to Miyazaki Prefectural Nobeoka Hospital, Japan with ACS from April 2008 to March 2010. Among them, the onset time of ACS was identified in 476 patients [age; 70.6±11.5, male; 68%, hypertension (HT); 83%, diabetes mellitus (DM); 32%, current smoking (cSM); 33%, Framingham risk score (FRS); 9.02±3.22]. The hourly circadian variation of ACS onset showed 2 peaks around 09:00 and 22:00. When we divided 24 hours into six-4hours each, there were significant differences in the distribution of patients among the time periods (p<0.01). One-sided binominal test showed one peak of the number of patients in the morning period: between 8:00 and 12:00 (119/ 476, 25%, p<0.01) and the patients included in the morning peak period were characterized by less obese, non-HT, non-DM, and non-cSM. FRS and the frequency of HT and cSM were significantly lower in the morning peak group than others (FRS; 8.31±3.38 vs. 9.25±3.14, p<0.01, HT; 72% vs. 87%, p<0.01, cSM; 23% vs. 36%, p=0.01). Multivariate logistic regression analysis revealed HT and cSM were independent variables associated with the morning peak of ACS [odds ratio (OR); 0.38 (95% confidence interval); 95%-CI 0.226-0.630, p<0.001, OR; 0.50 95%-CI; 0.310-0.819, p=0.006]. Logistic regression analysis revealed that FRS was significantly associated with the morning peak (OR; 0.91, 95%-CI; 0.849-0.975, p<0.01). Among anti-hypertensive medications, calcium channel blocker (CCB) use, but not β-blocker, was independently associated with the morning peak of ACS (OR; 0.56, 95%-CI; 0.353-0.901, p=0.02).
Conclusion Lower FRS, non-HT, non-cSM and less CCB use are associated with the morning peak in the circadian variation of ACS onset. Morning incidence of ACS might be affected by unknown pathogenesis rather than classical coronary risk factors.
- © 2012 by American Heart Association, Inc.