title: Circadian variation in acute myocardial infarct size assessed by cardiovascular magnetic resonance in reperfused STEMI patients.
abstract: OBJECTIVE
  Clinical studies using serum cardiac biomarkers to investigate a circadian variation in acute myocardial infarct (MI) size in ST-segment elevation myocardial infarction (STEMI) patients reperfused by primary percutaneous coronary intervention (PPCI) have produced mixed results. We aimed to investigate this phenomenon using acute MI size measured by cardiovascular magnetic resonance (CMR).
  
  
  METHODS
  Patient-level data was obtained from 4 randomized controlled trials investigating the MI-limiting effects of cardioprotective therapies in this pooled analysis. The primary analysis was performed in those patients with no pre-infarct angina; duration of ischemia >60min and <360min; Thrombolysis In Myocardial Infarction (TIMI) flow pre-PPCI ≤1; TIMI flow post-PPCI 3; and no collateral flow.
  
  
  RESULTS
  169 out of 376 patients with CMR data met the inclusion criteria for the primary analysis. A 24-hour circadian variation in acute MI size as a % of the area-at-risk (%AAR), after adjusting for confounders, was observed with a peak and nadir MI size in patients with symptom onset between 00:00 and 01:00 and between 12:00 and 13:00 respectively (difference from the average MI size 5.2%, 95%CI 1.1-9.4%; p=0.013). This was associated with a non-significant circadian variation in left ventricular ejection fraction (LVEF) (difference from the average LVEF 5.9%, 95%CI -0.6-2.2%, p=0.073). There was no circadian variation in MI size or LVEF in the whole cohort.
  
  
  CONCLUSIONS
  We report a circadian variation in acute MI size assessed by CMR in a subset of STEMI patients treated by PPCI, with the largest and smallest MI size occurring in patients with symptom onset between 00:00 and 01:00 and between 12:00 and 13:00 respectively.
authors.affiliation: The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, UK; The National Institute of Health Research University College London Hospitals Biomedical Research Centre, UK; National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore.
authors.forename: Heerajnarain
authors.initials: H
authors.lastname: Bulluck
authors.affiliation: London School Hygiene and Tropical Medicine, London, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Nicholas
authors.affiliation: Struttura Complessa Cardiologia, Fondazione Istituto Di Ricovero e Cura a Carattere Scientifico (IRCCS) Policlinico San Matteo, Pavia, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Crimi
authors.affiliation: The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, UK.
authors.forename: Steven K
authors.initials: SK
authors.lastname: White
authors.affiliation: Royal Devon and Exeter Hospital NHS Foundation Trust, Exeter, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Ludman
authors.affiliation: Struttura Complessa Cardiologia, Fondazione Istituto Di Ricovero e Cura a Carattere Scientifico (IRCCS) Policlinico San Matteo, Pavia, Italy; Struttura Complessa Cardiologia, Azienda Ospedaliera SS: Antonio e Biagio, Alessandria, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Pica
authors.affiliation: Struttura Complessa Cardiologia, Fondazione Istituto Di Ricovero e Cura a Carattere Scientifico (IRCCS) Policlinico San Matteo, Pavia, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Raineri
authors.affiliation: Institute of Biochemistry, Medical School, Justus-Liebig-University, Giessen, Germany; National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore; Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore, Singapore.
authors.forename: Hector A
authors.initials: HA
authors.lastname: Cabrera-Fuentes
authors.affiliation: The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, UK.
authors.forename: Derek
authors.initials: D
authors.lastname: Yellon
authors.affiliation: Cardiology Department, Vall d'Hebron Hospital, Universitat Autónoma de Barcelona, Barcelona, Spain.
authors.forename: Jose
authors.initials: J
authors.lastname: Rodriguez-Palomares
authors.affiliation: Cardiology Department, Vall d'Hebron Hospital, Universitat Autónoma de Barcelona, Barcelona, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Garcia-Dorado
authors.affiliation: The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, UK; The National Institute of Health Research University College London Hospitals Biomedical Research Centre, UK; National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore; Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore, Singapore. Electronic address: derek.hausenloy@duke-nus.edu.sg.
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Hausenloy
mesh_terms: D002940:Circadian Rhythm; D003326:Coronary Circulation / Q000502:physiology*; D018450:Disease Progression; D004562:Electrocardiography; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D062645:Percutaneous Coronary Intervention; D000072657:ST Elevation Myocardial Infarction / Q000097:blood / Q000175:diagnosis* / Q000601:surgery; D012720:Severity of Illness Index; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: Cardiovascular magnetic resonance; Circadian rhythm; Myocardial infarct size; ST-segment elevation myocardial infarction