title: Incidence of stunned, hibernating and scarred myocardium in ischaemic cardiomyopathy.
abstract: OBJECTIVE
  Different criteria to identify residual viability in chronically dysfunctioning myocardium in patients with coronary artery disease (CAD) can be derived by the combined assessment of myocardial blood flow (MBF) and glucose utilisation (MRG) using positron emission tomography (PET). The aim of this study was to evaluate, in a large number of patients, the prevalence of these different patterns by purely quantitative means.
  
  
  METHODS
  One hundred and sixteen consecutive patients with ischaemic cardiomyopathy (LVEF < or =40%) underwent resting 2D echocardiography to assess regional contractile function (16-segment model). PET with 15O-labelled water (H2 15O) and 18F-fluorodeoxyglucose (FDG) was used to quantify MBF and MRG during hyperinsulinaemic euglycaemic clamp. Dysfunctional segments with normal MBF (> or =0.6 ml min(-1) g(-1)) were classified as stunned, and segments with reduced MBF (<0.6 ml min(-1) g(-1)) as hibernating if MRG was > or =0.25 micromol min(-1) g(-1). Segments with reduced MBF and MRG <0.20 micromol min(-1) g(-1) were classified as transmural scars and segments with reduced MBF and MRG between 0.20 and 0.25 micromol min(-1) g(-1) as non-transmural scars.
  
  
  RESULTS
  Eight hundred and thirty-four (46%) segments were dysfunctional. Of these, 601 (72%) were chronically stunned, with 368 (61%) having normal MRG (0.47+/-0.20 micromol min(-1) g(-1)) and 233 (39%) reduced MRG (0.16+/-0.05 micromol min(-1) g(-1)). Seventy-four (9%) segments with reduced MBF had preserved MRG (0.40+/-0.18 micromol min(-1) g(-1)) and were classified as hibernating myocardium. In addition, 15% of segments were classified as transmural and 4% as non-transmural scar. The mean MBF was highest in stunned myocardium (0.95+/-0.32 ml min(-1) g(-1)), intermediate in hibernating myocardium and non-transmural scars (0.47+/-0.09 ml min(-1) g(-1) and 0.48+/-0.08 ml min(-1) g(-1), respectively), and lowest in transmural scars (0.40+/-0.14 ml min(-1) g(-1), P<0.01). MRG was comparable in hibernating and stunned myocardium with preserved MRG (0.40+/-0.19 micromol min(-1) g(-1) vs 0.46+/-0.20 micromol min(-1) g(-1), NS), and lowest in stunned myocardium with reduced MRG and transmural scars.
  
  
  CONCLUSIONS
  Chronic stunning is more prevalent than expected. The degree of MRG reduction in stunned myocardium may disclose segments at higher risk of permanent damage.
authors.affiliation: Medical Research Council Clinical Sciences Centre, Hammersmith Hospital, Imperial College, London, UK.
authors.forename: Miguel
authors.initials: M
authors.lastname: Hernandez-Pampaloni
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: Bax
authors.forename: Koichi
authors.initials: K
authors.lastname: Morita
authors.forename: David P
authors.initials: DP
authors.lastname: Dutka
authors.forename: Paolo G
authors.initials: PG
authors.lastname: Camici
mesh_terms: D009202:Cardiomyopathies / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D002908:Chronic Disease; D015897:Comorbidity; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000145:classification / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D017682:Myocardial Stunning / Q000000981:diagnostic imaging / Q000453:epidemiology; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data; D015995:Prevalence; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D006113:United Kingdom / Q000453:epidemiology; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000453:epidemiology*