Renal iodine123-metaiodobenzylguanidine scintigraphy relates to muscle sympathetic nervous activity in heart failure with reduced ejection fraction.

BACKGROUND

Renal denervation is effective for modulating augmented sympathetic nerve activity (SNA) in heart failure with reduced ejection fraction (HFrEF). We have demonstrated that renal iodine123-metaiodobenzylguanidine (123I-MIBG) scintigraphy is associated with muscle sympathetic nerve activity (MSNA) in patients with hypertension. However, it is unclear whether renal 123I-MIBG scintigraphy is useful for assessment of SNA in HFrEF.

METHODS

The study population consisted of 24 HFrEF patients and 11 healthy subjects as controls. Patients with HFrEF underwent 123I-MIBG scintigraphy and hemodynamics using a Swan-Ganz catheter (SGC). HFrEF was defined as echocardiography with left ventricular ejection fraction (LVEF) < 50%. MSNA was measured from the peroneal nerve for direct evaluation of SNA. Renal 123I-MIBG scintigraphy was performed simultaneously with cardiac scintigraphy. The early and delayed kidney-to-mediastinum ratio (K/M), early and delayed heart-to-mediastinum ratio (H/M), and washout rate (WR) were calculated.

RESULTS

LVEFs were 35% ± 11% in patients with HFrEF and 63% ± 10% in the controls (p < 0.01). The WR of cardiac 123I-MIBG showed no relation to MSNA, but was related to stroke volume (r = 0.45, p < 0.05). In contrast, the WR of renal 123I-MIBG scintigraphy (average of both sides) showed a strong correlation with MSNA (BI, r = 0.70, p < 0.01; BF, r = 0.66, p < 0.01); however, no significant correlations were detected between renal 123I-MIBG scintigraphy and SGC results.

CONCLUSIONS

The WR of renal 123I-MIBG scintigraphy may reflect MSNA. Further studies are needed to clarify the relationship between renal 123I-MIBG imaging and renal SNA.