title: Circadian Dependence of Infarct Size and Acute Heart Failure in ST Elevation Myocardial Infarction.
abstract: OBJECTIVE
  There are conflicting data on the relationship between the time of symptom onset during the 24-hour cycle (circadian dependence) and infarct size in ST-elevation myocardial infarction (STEMI). Moreover, the impact of this circadian pattern of infarct size on clinical outcomes is unknown. We sought to study the circadian dependence of infarct size and its impact on clinical outcomes in STEMI.
  
  
  METHODS
  We studied 6,710 consecutive patients hospitalized for STEMI from 2006 to 2009 in a tropical climate with non-varying day-night cycles. We categorized the time of symptom onset into four 6-hour intervals: midnight-6:00 A.M., 6:00 A.M.-noon, noon-6:00 P.M. and 6:00 P.M.-midnight. We used peak creatine kinase as a surrogate marker of infarct size.
  
  
  RESULTS
  Midnight-6:00 A.M patients had the highest prevalence of diabetes mellitus (P = 0.03), more commonly presented with anterior MI (P = 0.03) and received percutaneous coronary intervention less frequently, as compared with other time intervals (P = 0.03). Adjusted mean peak creatine kinase was highest among midnight-6:00 A.M. patients and lowest among 6:00 A.M.-noon patients (2,590.8±2,839.1 IU/L and 2,336.3±2,386.6 IU/L, respectively, P = 0.04). Midnight-6:00 A.M patients were at greatest risk of acute heart failure (P<0.001), 30-day mortality (P = 0.03) and 1-year mortality (P = 0.03), while the converse was observed in 6:00 A.M.-noon patients. After adjusting for diabetes, infarct location and performance of percutaneous coronary intervention, circadian variations in acute heart failure incidence remained strongly significant (P = 0.001).
  
  
  CONCLUSIONS
  We observed a circadian peak and nadir in infarct size during STEMI onset from midnight-6:00A.M and 6:00A.M.-noon respectively. The peak and nadir incidence of acute heart failure paralleled this circadian pattern. Differences in diabetes prevalence, infarct location and mechanical reperfusion may account partly for the observed circadian pattern of infarct size and acute heart failure.
authors.affiliation: Cardiac Department, National University Heart Centre, National University Hospital, Singapore, Singapore.
authors.forename: Aruni
authors.initials: A
authors.lastname: Seneviratna
authors.affiliation: National Registry of Diseases Office, (R&SP), Health Promotion Board, Singapore, Singapore.
authors.forename: Gek Hsiang
authors.initials: GH
authors.lastname: Lim
authors.affiliation: National Registry of Diseases Office, (R&SP), Health Promotion Board, Singapore, Singapore.
authors.forename: Anju
authors.initials: A
authors.lastname: Devi
authors.affiliation: Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore; Hospital Israelita Albert Einstein, Sao Paolo, Brazil.
authors.forename: Leonardo P
authors.initials: LP
authors.lastname: Carvalho
authors.affiliation: Department of Cardiology, National Heart Centre, Singapore, Singapore.
authors.forename: Terrance
authors.initials: T
authors.lastname: Chua
authors.affiliation: Department of Cardiology, National Heart Centre, Singapore, Singapore.
authors.forename: Tian-Hai
authors.initials: TH
authors.lastname: Koh
authors.affiliation: Cardiac Department, National University Heart Centre, National University Hospital, Singapore, Singapore.
authors.forename: Huay-Cheem
authors.initials: HC
authors.lastname: Tan
authors.affiliation: Department of Cardiology, Tan Tock Seng Hospital, Singapore, Singapore.
authors.forename: David
authors.initials: D
authors.lastname: Foo
authors.affiliation: Department of Cardiology, Changi General Hospital, Singapore, Singapore.
authors.forename: Khim-Leng
authors.initials: KL
authors.lastname: Tong
authors.affiliation: Department of Cardiology, Khoo Teck Puat Hospital, Singapore, Singapore.
authors.forename: Hean-Yee
authors.initials: HY
authors.lastname: Ong
authors.affiliation: Cardiac Department, National University Heart Centre, National University Hospital, Singapore, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: A Mark
authors.initials: AM
authors.lastname: Richards
authors.affiliation: National Registry of Diseases Office, (R&SP), Health Promotion Board, Singapore, Singapore.
authors.forename: Chow Khuan
authors.initials: CK
authors.lastname: Yew
authors.affiliation: Cardiac Department, National University Heart Centre, National University Hospital, Singapore, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Mark Y
authors.initials: MY
authors.lastname: Chan
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D002940:Circadian Rhythm; D052279:Creatine Kinase, MB Form / Q000097:blood; D048909:Diabetes Complications; D003920:Diabetes Mellitus / Q000097:blood / Q000175:diagnosis / Q000401:mortality; D005260:Female; D006333:Heart Failure / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000401:mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000401:mortality; D062645:Percutaneous Coronary Intervention; D017440:Photoperiod; D012189:Retrospective Studies; D012720:Severity of Illness Index; D016019:Survival Analysis; D013997:Time Factors; D014329:Tropical Climate
chemical_list: D015415:Biomarkers; D052279:Creatine Kinase, MB Form