ENHANCED CARDIAC CLEARANCE OF IODINE-123-MIBG IN CHRONIC-RENAL-FAILURE

We studied myocardial accumulation and clearance of [I-123]metaiodobenzylguanidine (MIBG) along with measurements of plasma norepinephrine concentrations. Methods: Myocardial imaging with MIBG and plasma norepinephrine concentration measurements were performed in 21 patients with chronic renal failure on dialysis and 11 control subjects. Dynamic acquisitions, begun immediately after MIBG injection, and planar images 15 and 150 min after injection were used to measure early and late myocardial uptake and clearance rates of MIBG from the heart. Results: Early and late MIBG uptake was not significantly different from that in controls but MIBG clearance was significantly more rapid in controls. Based on echocardiographic findings, the patients were divided into three subgroups: those without left ventricular hypertrophy and dysfunction (n = 10), with hypertrophy (n = 4) and with dysfunction (n = 7). Among controls and the three patient subgroups, MIBG clearance was significantly higher in all the subgroups and also was significantly higher in patients with dysfunction than in those without hypertrophy and dysfunction. Plasma norepinephrine levels were significantly higher in patients than in controls and correlated significantly with the clearance rate. Conclusion: MIBG clearance from the heart was rapid in patients with chronic renal failure on dialysis, particularly those with left ventricular dysfunction or hypertrophy, suggesting cardiac sympathetic overactivity in these patients.