title: Microvascular ischemia in hypertrophic cardiomyopathy: new insights from high-resolution combined quantification of perfusion and late gadolinium enhancement.
abstract: BACKGROUND
  Microvascular ischemia is one of the hallmarks of hypertrophic cardiomyopathy (HCM) and has been associated with poor outcome. However, myocardial fibrosis, seen on cardiovascular magnetic resonance (CMR) as late gadolinium enhancement (LGE), can be responsible for rest perfusion defects in up to 30% of patients with HCM, potentially leading to an overestimation of the ischemic burden. We investigated the effect of left ventricle (LV) scar on the total LV ischemic burden using novel high-resolution perfusion analysis techniques in conjunction with LGE quantification.
  
  
  METHODS
  30 patients with HCM and unobstructed epicardial coronary arteries underwent CMR with Fermi constrained quantitative perfusion analysis on segmental and high-resolution data. The latter were corrected for the presence of fibrosis on a pixel-by-pixel basis.
  
  
  RESULTS
  High-resolution quantification proved more sensitive for the detection of microvascular ischemia in comparison to segmental analysis. Areas of LGE were associated with significant reduction of myocardial perfusion reserve (MPR) leading to an overestimation of the total ischemic burden on non-corrected perfusion maps. Using a threshold MPR of 1.5, the presence of LGE caused an overestimation of the ischemic burden of 28%. The ischemic burden was more severe in patients with fibrosis, also after correction of the perfusion maps, in keeping with more severe disease in this subgroup.
  
  
  CONCLUSIONS
  LGE is an important confounder in the assessment of the ischemic burden in patients with HCM. High-resolution quantitative analysis with LGE correction enables the independent evaluation of microvascular ischemia and fibrosis and should be used when evaluating patients with HCM.
authors.affiliation: Division of Imaging Sciences, King's College London, Wellcome Trust/EPSRC Medical Engineering Centre, St Thomas' Hospital, London, UK. adriana.villa@kcl.ac.uk.
authors.forename: Adriana D M
authors.initials: AD
authors.lastname: Villa
authors.affiliation: Division of Imaging Sciences, King's College London, Wellcome Trust/EPSRC Medical Engineering Centre, St Thomas' Hospital, London, UK. eva.sammut@kcl.ac.uk.
authors.forename: Eva
authors.initials: E
authors.lastname: Sammut
authors.affiliation: Division of Imaging Sciences, King's College London, Wellcome Trust/EPSRC Medical Engineering Centre, St Thomas' Hospital, London, UK. niloufar.zarinabad@kcl.ac.uk.
authors.forename: Niloufar
authors.initials: N
authors.lastname: Zarinabad
authors.affiliation: Cardiology Department, St Thomas' Hospital, London, UK. gerry.carr-white@gstt.nhs.uk.
authors.forename: Gerald
authors.initials: G
authors.lastname: Carr-White
authors.affiliation: Division of Imaging Sciences, King's College London, Wellcome Trust/EPSRC Medical Engineering Centre, St Thomas' Hospital, London, UK. jack.lee@kcl.ac.uk.
authors.forename: Jack
authors.initials: J
authors.lastname: Lee
authors.affiliation: Hospital Center Vila Nova Gaia, Porto, Portugal. bettencourt.n@gmail.com.
authors.forename: Nuno
authors.initials: N
authors.lastname: Bettencourt
authors.affiliation: Division of Imaging Sciences, King's College London, Wellcome Trust/EPSRC Medical Engineering Centre, St Thomas' Hospital, London, UK. reza.razavi@kcl.ac.uk.
authors.forename: Reza
authors.initials: R
authors.lastname: Razavi
authors.affiliation: DZHK Centre for Cardiovascular Imaging, University Hospital Frankfurt / Main, Frankfurt am Main, Germany. eike.nagel@cardiac-imaging.org.
authors.forename: Eike
authors.initials: E
authors.lastname: Nagel
authors.affiliation: Division of Imaging Sciences, King's College London, Wellcome Trust/EPSRC Medical Engineering Centre, St Thomas' Hospital, London, UK. amedeo.chiribiri@kcl.ac.uk.|Division of Imaging Sciences and Biomedical Engineering, King's College London, The Rayne Institute - 4th Floor Lambeth Wing, St Thomas' Hospital, SE1 7EH, London, UK. amedeo.chiribiri@kcl.ac.uk.
authors.forename: Amedeo
authors.initials: A
authors.lastname: Chiribiri
mesh_terms: D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D002921:Cicatrix / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D003287:Contrast Media; D003326:Coronary Circulation; D005240:Feasibility Studies; D005260:Female; D005355:Fibrosis; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D009206:Myocardium / Q000473:pathology*; D009942:Organometallic Compounds; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol