title: Blunted myocardial oxygenation response during vasodilator stress in patients with hypertrophic cardiomyopathy.
abstract: OBJECTIVE
  This study sought to assess myocardial perfusion and tissue oxygenation during vasodilator stress in patients with overt hypertrophic cardiomyopathy (HCM), as well as in HCM mutation carriers without left ventricular (LV) hypertrophy, and to compare findings to those in athletes with comparable hypertrophy and normal controls.
  
  
  BACKGROUND
  Myocardial perfusion under vasodilator stress is impaired in patients with HCM. Whether this is associated with impaired myocardial oxygenation and tissue ischemia is unknown. Furthermore, it is not known whether perfusion and oxygenation are impaired in HCM mutation carriers without left ventricular hypertrophy (LVH).
  
  
  METHODS
  A total of 27 patients with overt HCM, 10 HCM mutation carriers without LVH, 11 athletes, and 20 healthy controls underwent cardiovascular magnetic resonance (CMR) scanning at 3-T. Myocardial function, perfusion (perfusion reserve index [MPRI]), and oxygenation (blood-oxygen level dependent signal intensity [SI] change) under adenosine stress were assessed.
  
  
  RESULTS
  MPRI was significantly reduced in HCM (1.3 ± 0.1) compared to controls (1.8 ± 0.1, p < 0.001) and athletes (2.0 ± 0.1, p < 0.001), but remained normal in HCM mutation carriers without LVH (1.7 ± 0.1; p = 0.61 vs. controls, p = 0.02 vs. overt HCM). Oxygenation response was attenuated in overt HCM (SI change 6.9 ± 1.4%) compared to controls (18.9 ± 1.4%, p < 0.0001) and athletes (18.7 ± 2.0%, p < 0.001). Interestingly, HCM mutation carriers without LVH also showed an impaired oxygenation response to adenosine (10.4 ± 2.0%; p = 0.001 vs. controls, p = 0.16 vs. overt HCM, p = 0.003 vs. athletes).
  
  
  CONCLUSIONS
  In overt HCM, both perfusion and oxygenation are impaired during vasodilator stress. However, in HCM mutation carriers without LVH, only oxygenation is impaired. In athletes, stress perfusion and oxygenation are normal. CMR assessment of myocardial oxygenation has the potential to become a novel risk factor in HCM.
authors.affiliation: University of Oxford Centre for Clinical Magnetic Resonance Research, Department of Cardiovascular Medicine, John Radcliffe Hospital, Oxford, United Kingdom. theo.karamitsos@cardiov.ox.ac.uk
authors.forename: Theodoros D
authors.initials: TD
authors.lastname: Karamitsos
authors.forename: Sairia
authors.initials: S
authors.lastname: Dass
authors.forename: Joseph
authors.initials: J
authors.lastname: Suttie
authors.forename: Emily
authors.initials: E
authors.lastname: Sever
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Birks
authors.forename: Cameron J
authors.initials: CJ
authors.lastname: Holloway
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Robson
authors.forename: Michael
authors.initials: M
authors.lastname: Jerosch-Herold
authors.forename: Hugh
authors.initials: H
authors.lastname: Watkins
authors.forename: Stefan
authors.initials: S
authors.lastname: Neubauer
mesh_terms: D000241:Adenosine; D000328:Adult; D002312:Cardiomyopathy, Hypertrophic / Q000378:metabolism* / Q000503:physiopathology*; D003326:Coronary Circulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption; D014665:Vasodilator Agents
chemical_list: D014665:Vasodilator Agents; D000241:Adenosine