title: Iodine-123 metaiodobenzylguanidine scintigraphic assessment of myocardial sympathetic innervation in patients with familial amyloid polyneuropathy.
abstract: OBJECTIVE
  This study attempted to assess myocardial sympathetic innervation using iodine-123 (I-123) metaidobenzylguanidine (MIBG) imaging in patients with familial amyloid polyneuropathy.
  
  
  BACKGROUND
  Signs and symptoms of cardiac autonomic dysfunction are commonly seen in patients with cardiac amyloidosis. However, the incidence and magnitude of abnormalities in myocardial sympathetic nerve function by means of I-123 MIBG imaging and their relation to clinical findings, cardiac function and the results of thallium-201 (Tl-201) and technetium-99m pyrophosphate (Tc-99m PYP) myocardial scanning have not yet been clarified.
  
  
  METHODS
  We performed M-mode, two-dimensional and Doppler echocardiography and I-123 MIBG, Tl-201 and Tc-99m PYP imaging of the heart in 12 patients with familial amyloid polyneuropathy and biopsy-proved cardiac amyloidosis.
  
  
  RESULTS
  Ten of 12 patients had no clinical evidence of overt heart disease, but left ventricular (LV) wall thickening was observed in 4 of these 10. Left ventricular percent fractional shortening and Doppler transmitral flow velocity patterns were found to be normal in all 12 patients. Eight of 12 patients showed no myocardial MIBG accumulation, with limited uptake in the remaining 4 demonstrated only in the LV anterior wall. Diffuse but mild myocardial uptake of Tc-99m PYP occurred in only 4 of 12 patients, and all 12 had normal results on Tl-201 myocardial scanning. Complete defects on myocardial MIBG scans were found in five of eight patients with negative findings on Tc-99m PYP myocardial scanning. The incidence and magnitude of myocardial uptake of MIBG were independent of clinical findings, extent of endomyocardial amyloid deposition, electrocardiographic QRS voltage and ventricular wall thickness.
  
  
  CONCLUSIONS
  Patients with familial amyloid polyneuropathy show a high incidence of myocardial adrenergic denervation with viable myocardium that can be identified very early in cardiac amyloidosis, before the development of clinically apparent heart disease, ventricular wall thickening, significant LV systolic and diastolic dysfunction and positive findings on Tc-99m PYP myocardial scanning.
authors.affiliation: First Department of Internal Medicine, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Tanaka
authors.forename: M
authors.initials: M
authors.lastname: Hongo
authors.forename: O
authors.initials: O
authors.lastname: Kinoshita
authors.forename: Y
authors.initials: Y
authors.lastname: Takabayashi
authors.forename: T
authors.initials: T
authors.lastname: Fujii
authors.forename: Y
authors.initials: Y
authors.lastname: Yazaki
authors.forename: M
authors.initials: M
authors.lastname: Isobe
authors.forename: M
authors.initials: M
authors.lastname: Sekiguchi
mesh_terms: D019797:3-Iodobenzylguanidine; D000328:Adult; D017772:Amyloid Neuropathies / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001342:Autonomic Nervous System Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D009202:Cardiomyopathies / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003287:Contrast Media; D004452:Echocardiography; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging* / Q000294:innervation; D006801:Humans; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D008297:Male; D011877:Radionuclide Imaging; D016698:Technetium Tc 99m Pyrophosphate; D013794:Thallium Radioisotopes
chemical_list: D003287:Contrast Media; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D013794:Thallium Radioisotopes; D019797:3-Iodobenzylguanidine; D016698:Technetium Tc 99m Pyrophosphate