title: Assessment of the longitudinal changes in infarct heterogeneity post myocardial infarction.
abstract: Infarct heterogeneity, as assessed by determination of the peri-infarct zone (PIZ) by cardiac magnetic resonance imaging, has been shown to be an independent predictor for the development of cardiac arrhythmias and mortality post myocardial infarction (MI). The temporal evolution of the PIZ post MI is currently unknown. Thus, the main objective of our study was to describe the temporal evolution of the PIZ over a 6 month time period in contemporarily managed ST elevation myocardial infarction (STEMI) patients. Further, given the poor prognosis associated with microvascular obstruction (MVO) post STEMI, we sought to compare the temporal evolution of the PIZ in patients with and without MVO. We hypothesized that patients with MVO would show a relative persistence of PIZ over time when compared to those without MVO.
  
  
  
  Twenty-one patients post primary percutaneous coronary intervention were enrolled and treated with evidence based therapy. Each patient had three cardiac MRI scans at 48 h, 3 weeks and 6 months post infarction. Repeated Measures Analysis of Variance (ANOVA) was used to assess the evolution of core infarct size and peri-infarct zone size across the three time frames.
  
  
  
  The patients in this study were predominantly male, with ~40 % LAD territory infarction and a mean LVEF of 46 ± 7 %. Core infarct size and PIZ size both decreased significantly across the three time frames. The presence of microvascular obstruction (MVO), a known adverse prognostic factor, influenced PIZ size. Both patients with and without MVO had a significant reduction in core infarct size over time. Patients with MVO did not have a significant change in PIZ size over time (11.9 ± 6.8 %, 12.2 ± 7.5 %, 10.7 ± 6.6 % p = 0.77). In contrast, non-MVO patients did have a significant decrease in PIZ size over time (7.0 ± 5.5 %, 7.1 ± 6.5 %, 2.7 ± 2.6 %, p = 0.01).
  
  
  
  Peri-infarct zone size, like core infarct size, varies depending upon the timing of measurement. Patients with MVO displayed a persistence of the PIZ over time.
authors.affiliation: Sunnybrook Research Institute, Schulich Heart Program, Sunnybrook Health Sciences Centre and the University of Toronto, 2075 Bayview Avenue, room M 315b, Toronto, ON, M4N-3M5, Canada. idan.roifman@utoronto.ca.
authors.forename: Idan
authors.initials: I
authors.lastname: Roifman
authors.affiliation: Sunnybrook Research Institute, Schulich Heart Program, Sunnybrook Health Sciences Centre and the University of Toronto, 2075 Bayview Avenue, room M 315b, Toronto, ON, M4N-3M5, Canada.|Physical Sciences Platform, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre and the University of Toronto, Toronto, ON, Canada.|Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
authors.forename: Nilesh R
authors.initials: NR
authors.lastname: Ghugre
authors.affiliation: Sunnybrook Research Institute, Schulich Heart Program, Sunnybrook Health Sciences Centre and the University of Toronto, 2075 Bayview Avenue, room M 315b, Toronto, ON, M4N-3M5, Canada.
authors.forename: Tasnim
authors.initials: T
authors.lastname: Vira
authors.affiliation: Sunnybrook Research Institute, Schulich Heart Program, Sunnybrook Health Sciences Centre and the University of Toronto, 2075 Bayview Avenue, room M 315b, Toronto, ON, M4N-3M5, Canada.
authors.forename: Mohammad I
authors.initials: MI
authors.lastname: Zia
authors.affiliation: Sunnybrook Research Institute, Schulich Heart Program, Sunnybrook Health Sciences Centre and the University of Toronto, 2075 Bayview Avenue, room M 315b, Toronto, ON, M4N-3M5, Canada.|Division of Cardiothoracic Imaging, Department of Medical Imaging, Sunnybrook Health Sciences Centre and the University of Toronto, Toronto, ON, Canada.
authors.forename: Anna
authors.initials: A
authors.lastname: Zavodni
authors.affiliation: Sunnybrook Research Institute, Schulich Heart Program, Sunnybrook Health Sciences Centre and the University of Toronto, 2075 Bayview Avenue, room M 315b, Toronto, ON, M4N-3M5, Canada.|Physical Sciences Platform, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre and the University of Toronto, Toronto, ON, Canada.|Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
authors.forename: Mihaela
authors.initials: M
authors.lastname: Pop
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, The University of Toronto, Toronto, ON, Canada.
authors.forename: Kim A
authors.initials: KA
authors.lastname: Connelly
authors.affiliation: Sunnybrook Research Institute, Schulich Heart Program, Sunnybrook Health Sciences Centre and the University of Toronto, 2075 Bayview Avenue, room M 315b, Toronto, ON, M4N-3M5, Canada.|Physical Sciences Platform, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre and the University of Toronto, Toronto, ON, Canada.|Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
authors.forename: Graham A
authors.initials: GA
authors.lastname: Wright
mesh_terms: D003326:Coronary Circulation / Q000502:physiology*; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology*; D062645:Percutaneous Coronary Intervention; D011446:Prospective Studies; D000072657:ST Elevation Myocardial Infarction / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D012720:Severity of Illness Index; D013997:Time Factors
keywords: Cardiac magnetic resonance imaging; Gray zone/Peri-infarct zone; Infarct heterogeneity; ST elevation myocardial infarction (STEMI)