title: Cardiac sympathetic activity pre and post resynchronization therapy evaluated by 123I-MIBG myocardial scintigraphy.
abstract: BACKGROUND
  Imaging with (123)I-metaiodobenzylguanidine (MIBG) is used for the assessment of cardiac sympathetic activity (CSA). We analyzed CSA before and after cardiac resynchronization therapy (CRT), and correlated these data with CRT response.
  
  
  RESULTS
  Thirty patients with chronic heart failure and classic indications for CRT were prospectively studied before and at least 3 months after CRT. The variables analyzed were: QRS width, left-ventricular ejection fraction (LVEF), left-ventricular end-diastolic diameter (LVEDD), heart/mediastinum MIBG uptake ratio (H/M), and washout rate (WR). After CRT, patients were divided into two groups: group 1 (21 patients), responders improving to functional class (FC) I or II; and group 2 (9 patients), nonresponders remaining in FC III or IV. After CRT, only group 1 showed favorable changes in QRS width (P =.003), LVEF (P =.01), LVEDD (P =.04), and H/M ratio (P =.003). The H/M ratio and WR were associated with CRT response (P =.005 and P =.04, respectively). The H/M ratio was the only independent predictor of CRT response (P =.01). Receiver operating characteristic curves showed that the optimal H/M ratio cutoff point was 1.36 (sensitivity, 75%; specificity, 71%).
  
  
  CONCLUSIONS
  Improvement in CSA correlated with a positive CRT response. Lower MIBG uptake before therapy was associated with CRT nonresponse. The H/M ratio could be helpful in selecting patients for CRT.
authors.affiliation: Department of Arrhythmia and Cardiac Stimulation, Heart Institute, InCor, University of São Paulo Medical School, São Paulo, Brazil. silvanadorio@uol.com.br
authors.forename: Silvana A D'Orio
authors.initials: SA
authors.lastname: Nishioka
authors.forename: Martino
authors.initials: M
authors.lastname: Martinelli Filho
authors.forename: Simone C Soares
authors.initials: SC
authors.lastname: Brandão
authors.forename: Maria Clementina
authors.initials: MC
authors.lastname: Giorgi
authors.forename: Marcelo L C
authors.initials: ML
authors.lastname: Vieira
authors.forename: Roberto
authors.initials: R
authors.lastname: Costa
authors.forename: Wilson
authors.initials: W
authors.lastname: Mathias
authors.forename: José Cláudio
authors.initials: JC
authors.lastname: Meneghetti
mesh_terms: D019797:3-Iodobenzylguanidine; D000328:Adult; D001342:Autonomic Nervous System Diseases / Q000150:complications / Q000000981:diagnostic imaging* / Q000628:therapy*; D002303:Cardiac Output, Low / Q000000981:diagnostic imaging* / Q000209:etiology / Q000517:prevention & control*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D011379:Prognosis; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine