Myocardial sympathetic innervation does not predict short-term cardiac events in patients with dilated cardiomyopathy: A study with I-123 MIBG SPECT

17 Objectives : In order to investigate whether the myocardial sympathetic activity has a prognostic significance in dilated cardiomyopathy (DCMP), we evaluated myocardial sympathetic innervation in patients with DCMP using I-123 metaiodobenzylguanidine (MIBG) SPECT and compared with disease progression. Methods : I-123 MIBG SPECT was performed in 17 patients (age, 63.5±10.7 y; M/F = 11/6,) with DCMP (15 idiopathic and 2 ischemic). Both planar and SPECT myocardial images were acquired 15 min and 4 h after injection of 185 MBq I-123 MIBG. Heart-to-mediastium ratio (H/M) and washout rate (WR) were calculated on planar images. On SPECT images, total uptake score (TUS), defined as sum of myocardial segment uptake scores using a 20-segment and 3-point scale model, was calculated. Disease progression was defined as a decline of ejection fraction > 5% and/or hospitalization due to aggravation of dyspnea. The median follow-up period was 14.0 mo. Results : There was a significant inverse correlation between WR and TUS at 4 h (r = -0.705, P < 0.01). Five (29.4%) of the 17 patients had a disease progression during the median follow-up period of 13.1 mo. Cox proportion hazard regression analysis revealed no significant parameters for disease progression among variables including H/M, WR, TUS, and deltaTUS between 15 min and 4 h. Conclusions : These data indicate that the myocardial sympathetic activity measured by I-123 MIBG SPECT dose not predict short-term disease progression in patients with DCMP.