title: Myocardial Infarct Size by CMR in Clinical Cardioprotection Studies: Insights From Randomized Controlled Trials.
abstract: The aim of this study was to review randomized controlled trials (RCTs) using cardiac magnetic resonance (CMR) to assess myocardial infarct (MI) size in reperfused patients with ST-segment elevation myocardial infarction (STEMI).
  
  
  
  There is limited guidance on the use of CMR in clinical cardioprotection RCTs in patients with STEMI treated by primary percutaneous coronary intervention.
  
  
  
  All RCTs in which CMR was used to quantify MI size in patients with STEMI treated with primary percutaneous coronary intervention were identified and reviewed.
  
  
  
  Sixty-two RCTs (10,570 patients, January 2006 to November 2016) were included. One-third did not report CMR vendor or scanner strength, the contrast agent and dose used, and the MI size quantification technique. Gadopentetate dimeglumine was most commonly used, followed by gadoterate meglumine and gadobutrol at 0.20 mmol/kg each, with late gadolinium enhancement acquired at 10 min; in most RCTs, MI size was quantified manually, followed by the 5 standard deviation threshold; dropout rates were 9% for acute CMR only and 16% for paired acute and follow-up scans. Weighted mean acute and chronic MI sizes (≤12 h, initial TIMI [Thrombolysis in Myocardial Infarction] flow grade 0 to 3) from the control arms were 21 ± 14% and 15 ± 11% of the left ventricle, respectively, and could be used for future sample-size calculations. Pre-selecting patients most likely to benefit from the cardioprotective therapy (≤6 h, initial TIMI flow grade 0 or 1) reduced sample size by one-third. Other suggested recommendations for standardizing CMR in future RCTs included gadobutrol at 0.15 mmol/kg with late gadolinium enhancement at 15 min, manual or 6-SD threshold for MI quantification, performing acute CMR at 3 to 5 days and follow-up CMR at 6 months, and adequate reporting of the acquisition and analysis of CMR.
  
  
  
  There is significant heterogeneity in RCT design using CMR in patients with STEMI. The authors provide recommendations for standardizing the assessment of MI size using CMR in future clinical cardioprotection RCTs.
authors.affiliation: The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, United Kingdom; The National Institute of Health Research University College London Hospitals Biomedical Research Center, London, United Kingdom; National Heart Research Institute Singapore, National Heart Center Singapore, Singapore, Singapore.
authors.forename: Heerajnarain
authors.initials: H
authors.lastname: Bulluck
authors.affiliation: The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, United Kingdom.
authors.forename: Matthew
authors.initials: M
authors.lastname: Hammond-Haley
authors.affiliation: The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, United Kingdom.
authors.forename: Shane
authors.initials: S
authors.lastname: Weinmann
authors.affiliation: The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, United Kingdom.
authors.forename: Roberto
authors.initials: R
authors.lastname: Martinez-Macias
authors.affiliation: The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, United Kingdom; The National Institute of Health Research University College London Hospitals Biomedical Research Center, London, United Kingdom; National Heart Research Institute Singapore, National Heart Center Singapore, Singapore, Singapore; Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore, Singapore, Singapore. Electronic address: derek.hausenloy@duke-nus.edu.sg.
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Hausenloy
mesh_terms: D003287:Contrast Media / Q000008:administration & dosage; D019317:Evidence-Based Medicine; D005682:Gadolinium / Q000008:administration & dosage; D006801:Humans; D008279:Magnetic Resonance Imaging; D015425:Myocardial Reperfusion / Q000009:adverse effects / Q000401:mortality; D009206:Myocardium / Q000473:pathology*; D011237:Predictive Value of Tests; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D012107:Research Design; D000072657:ST Elevation Myocardial Infarction / Q000000981:diagnostic imaging* / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media; D005682:Gadolinium
keywords: ST-segment elevation myocardial infarction; cardiovascular magnetic resonance; myocardial infarct size; primary percutaneous coronary intervention; randomized controlled trial; sample size