title: Changes in cardiac sympathetic nerve innervation and activity in pathophysiologic transition from typical to end-stage hypertrophic cardiomyopathy.
abstract: Left ventricular (LV) systolic function in hypertrophic cardiomyopathy (HCM) is usually normal. Late in the disease, however, LV systolic dysfunction and dilatation are recognized. Although abnormalities in cardiac sympathetic nerve activity in patients with HCM have been demonstrated using (123)I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy, the changes of cardiac sympathetic nerve activity throughout the clinical course from typical to end-stage HCM are unclear. The objective of this study was to evaluate the relationship between abnormalities on (123)I-MIBG myocardial scintigraphy and pathophysiologic changes in patients with HCM.
  
  
  METHODS
  We performed (123)I-MIBG scintigraphy on 46 patients with HCM and 18 age-matched control subjects. The patients were categorized into 3 groups: 28 patients with normal LV systolic function (group A), 9 patients with LV systolic dysfunction (group B), and 9 patients with LV systolic dysfunction and dilatation (group C). With planar (123)I-MIBG imaging, the heart-to-mediastinum ratio for early and delayed acquisitions and the washout rate were calculated. With SPECT, polar maps of the LV myocardium were divided into 20 segments. The regional uptake and washout rate were calculated from semiquantitative 20-segment bull's-eye analysis.
  
  
  RESULTS
  The early uptake was significantly lower in group C than in the control group (P < 0.01). The washout rate was progressively higher in group A, group B, and group C (P < 0.01). Reduced regional early uptake was found in 2.9 +/- 3.4 (group A), 4.1 +/- 4.7 (group B), and 7.4 +/- 4.3 (group C) segments, respectively. In group C, regional early uptake was significantly reduced, predominantly in the interventricular septal wall, and regional washout rate was increased in the apex and lateral wall.
  
  
  CONCLUSIONS
  These results suggest that cardiac sympathetic nerve abnormalities in patients with HCM may advance with development of LV systolic dysfunction and dilatation and that (123)I-MIBG myocardial scintigraphy may be a useful tool for the evaluation of pathophysiologic changes in HCM.
authors.affiliation: Molecular Genetics of Cardiovascular Disorders, Division of Cardiovascular Medicine, Kanazawa University, Kanazawa, Japan. yonken1@med.kanazawa-u.ac.jp
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Terai
authors.forename: Masami
authors.initials: M
authors.lastname: Shimizu
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Ino
authors.forename: Masato
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Katsuharu
authors.initials: K
authors.lastname: Uchiyama
authors.forename: Kotaro
authors.initials: K
authors.lastname: Oe
authors.forename: Kenichi
authors.initials: K
authors.lastname: Nakajima
authors.forename: Junichi
authors.initials: J
authors.lastname: Taki
authors.forename: Masaya
authors.initials: M
authors.lastname: Kawano
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mabuchi
mesh_terms: D019797:3-Iodobenzylguanidine / Q000493:pharmacokinetics*; D000328:Adult; D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications / Q000000981:diagnostic imaging* / Q000378:metabolism; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000294:innervation* / Q000378:metabolism; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D013564:Sympathetic Nervous System / Q000000981:diagnostic imaging* / Q000378:metabolism; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology / Q000378:metabolism
chemical_list: D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine