Sympathetic reinnervation 1 year after heart transplantation, assessed using iodine-123 metaiodobenzylguanidine imaging.

Complete allograft denervation occurs during heart transplantation (HT). Partial ventricular sympathetic reinnervation that may develop after transplantation can be measured using iodine-123 meta iodobenzylguanidine (MIBG) uptake. Previous studies have suggested that reinnervation is likely to be a slow process, only occurring after 1 year posttransplantation. However, the reinnervation prevalence at 1 year after HT remains unknown. This study sought to determine sympathetic reinnervation measured by MIBG at 12 months after surgery. We performed serial cardiac MIBG imaging in 45 cardiac transplant recipients, including 32 males and 13 females, early (2 months) and late (12 months) after the operation. The intensity of myocardial MIBG uptaken was quantified by heart-to-mediastinum ratios (HMR). Reinnervation was considered when the HMR was >1.3. HMR was significantly higher at 12 months: 1.16 ± 0.10 at 2 vs 1.30 ± 0.15 at 12 months (P < .001). Eighteen (40%) of 45 subjects developed visible cardiac MIBG uptake at 1 year after transplantation with HMR >1.3. In conclusion, partial sympathetic reinnervation increases with time after HT; it was seen in 40% of patients at 1 year after the operation.