Renal Function in Relation to Cardiac (123)I-MIBG Scintigraphy in Patients with Chronic Heart Failure

The aim of this study was to explore if estimates of renal function could explain variability of (123)I-metaiodobenzylguanidine ((123)I-MIBG) assessed myocardial sympathetic activity. Furthermore estimates of renal function were compared to (123)I-MIBG as predictors of cardiac death in chronic heart failure (CHF). Semi-quantitative parameters of (123)I-MIBG myocardial uptake and washout were calculated using early heart/mediastinum ratio (H/M), late H/M and washout. Renal function was calculated as estimated Creatinine Clearance (e-CC) and as estimated Glomerular Filtration Rate (e-GFR). Thirty-nine patients with CHF (24 males; age: 64.4 ± 10.5 years; NYHA II/III/IV: 17/20/2; LVEF: 24.0 ± 11.5%) were studied. Variability in any of the semi-quantitative (123)I-MIBG myocardial parameters could not be explained by e-CC or e-GFR. During follow-up (60 ± 37 months) there were 6 cardiac deaths. Cox proportional hazard regression analysis showed that late H/M was the only independent predictor for cardiac death (Chi-square 3.2, regression coefficient: -4.095; standard error: 2.063; hazard ratio: 0.17 [95% CI: 0.000-0.950]). Addition of estimates of renal function did not significantly change the Chi-square of the model. Semi-quantitative (123)I-MIBG myocardial parameters are independent of estimates of renal function. In addition, cardiac sympathetic innervation assessed by (123)I-MIBG scintigraphy seems to be superior to renal function in the prediction of cardiac death in CHF patients.