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

We studied myocardial accumulation and clearance of [I-123]metaiodoben zylguanidine (MIBG) along with measurements of plasma norepinephrine c oncentrations. Methods: Myocardial imaging with MIBG and plasma norepi nephrine concentration measurements were performed in 21 patients with chronic renal failure on dialysis and 11 control subjects. Dynamic ac quisitions, begun immediately after MIBG injection, and planar images 15 and 150 min after injection were used to measure early and late myo cardial uptake and clearance rates of MIBG from the heart. Results: Ea rly 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 th ree subgroups: those without left ventricular hypertrophy and dysfunct ion (n = 10), with hypertrophy (n = 4) and with dysfunction (n = 7). A mong controls and the three patient subgroups, MIBG clearance was sign ificantly higher in all the subgroups and also was significantly highe r in patients with dysfunction than in those without hypertrophy and d ysfunction. Plasma norepinephrine levels were significantly higher in patients than in controls and correlated significantly with the cleara nce rate. Conclusion: MIBG clearance from the heart was rapid in patie nts with chronic renal failure on dialysis, particularly those with le ft ventricular dysfunction or hypertrophy, suggesting cardiac sympathe tic overactivity in these patients.