Cardiac sympathetic activity pre and post resynchronization therapy evaluated by 123I-MIBG myocardial scintigraphy.
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.
Nishioka
Silvana A D'Orio
SA
Department of Arrhythmia and Cardiac Stimulation, Heart Institute, InCor, University of São Paulo Medical School, São Paulo, Brazil. silvanadorio@uol.com.br
Martinelli Filho
Martino
M
Brandão
Simone C Soares
SC
Giorgi
Maria Clementina
MC
Vieira
Marcelo L C
ML
Costa
Roberto
R
Mathias
Wilson
W
Meneghetti
José Cláudio
JC
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
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine