title: Sustained ventricular tachycardia is associated with regional myocardial sympathetic denervation assessed with 123I-metaiodobenzylguanidine in chronic Chagas cardiomyopathy.
abstract: Cardiac sympathetic denervation and ventricular arrhythmia are frequently observed in chronic Chagas cardiomyopathy (CCC). This study quantitatively evaluated the association between cardiac sympathetic denervation and sustained ventricular tachycardia (SVT) in patients with CCC.
  
  
  METHODS
  We prospectively investigated patients with CCC and left ventricular ejection fraction (LVEF) greater than 35% with SVT (SVT group: n = 15; mean age ± SD, 61 ± 8 y; LVEF, 51% ± 8%) and patients without SVT (non-SVT group: n = 11; mean age ± SD, 55 ± 10 y; LVEF, 57% ± 10%). Patients underwent myocardial scintigraphy with (123)I-metaiodobenzylguanidine ((123)I-MIBG) for the evaluation of sympathetic innervation and resting perfusion with (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) for the evaluation of myocardial viability. A visual semiquantitative score was attributed for regional uptake of each radiotracer using a 17-segment left ventricular segmentation model (0, normal; 4, absence of uptake). A mismatch defect was defined as occurring in segments with a (99m)Tc-MIBI uptake score of 0 or 1 and a (123)I-MIBG score of 2 or more.
  
  
  RESULTS
  Compared with the non-SVT group, the SVT group had a similar (99m)Tc-MIBI summed score (6.9 ± 7.5 vs. 4.4 ± 5.2, respectively, P = 0.69) but a higher (123)I-MIBG summed score (10.9 ± 7.8 vs. 22.4 ± 9.5, respectively, P = 0.007) and a higher number of mismatch defects per patient (2.0 ± 2.2 vs. 7.1 ± 2.0, respectively, P < 0.0001). The presence of more than 3 mismatch defects was strongly associated with the presence of SVT (93% sensitivity, 82% specificity; P = 0.0002).
  
  
  CONCLUSIONS
  In CCC, the amount of sympathetically denervated viable myocardium is associated with the occurrence of SVT. Myocardial sympathetic denervation may participate in triggering malignant ventricular arrhythmia in CCC patients with relatively well-preserved ventricular function.
authors: Division of Cardiology, Department of Internal Medicine, University Hospital, Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors: Carlos H
authors: CH
authors: Miranda
authors: Alexandre B
authors: AB
authors: Figueiredo
authors: Benedito C
authors: BC
authors: Maciel
authors: José Antônio
authors: JA
authors: Marin-Neto
authors: Marcus Vinícius
authors: MV
authors: Simões
mesh_terms: D019797:3-Iodobenzylguanidine; D000368:Aged; D014355:Chagas Disease / Q000000981:diagnostic imaging* / Q000473:pathology*; D003324:Coronary Artery Disease / Q000150:complications / Q000000981:diagnostic imaging; D003326:Coronary Circulation / Q000502:physiology; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D013562:Sympathectomy; D013564:Sympathetic Nervous System / Q000000981:diagnostic imaging* / Q000503:physiopathology; D017180:Tachycardia, Ventricular / Q000209:etiology*
chemical_list: D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine