Abstract
Introduction
In heart failure (HF) a strict interaction exists between heart and kidney. Previous studies reported a significant impact of sympathetic overdrive, that causes beta-adrenoceptor desensitization, in both renal and heart failure progression. It can be hypothesized that renal failure might be associated with impaired sympathetic activity assessed directly at the myocardial level in patients affected by HF.
Purpose
Aim of the present observational study was to assess the relationship between renal dysfunction and cardiac sympathetic innervation in HF patients with mildly and severely reduced ejection fraction (HFrEF and HFmEF).
Methods
Two-hundred and sixty-three patients (84% males; 66±10.8 years) with mild-to-severe HF (EF 31±6.8%) underwent iodine-123 meta-iodobenzylguanidine (123I-MIBG) myocardial scintigraphy to assess sympathetic innervation, evaluating early and late heart to mediastinum (H/M) ratios and washout rate. All patients also underwent clinical evaluation and venous blood sample collection for the assessment of serum creatinine and consequently the estimation of glomerular filtration rate (eGFR) by EPI formula.
Results
A direct correlation was found between EPI-eGFR and late H/M (r=0,215; p<0.001) (figure 1), with an inverse correlation between NYHA class and late H/M (r=0,152; p=0.013), and a direct correlation between left ventricular EF and late H/M (r=0,348; p<0.001). These results were not confirmed for early H/M, nor washout rate. Dividing the population in reduced eGFR and normal eGFR (cut-off ≤60 ml/min/1,73m2), a statistical significant reduction of late H/M value was found in patients with reduced eGFR (late H/M = 1,49±0,21) compared with patients with preserved eGFR (late H/M = 1,56±0,26) (p=0.020). In a multivariate model, adjusting eGFR for NYHA class and left ventricular EF, reduced eGFR and left ventricular EF remained significant predictors of reduced late H/M (p=0.006 and p<0.001, respectively).
Figure 1. linear regression curve
Conclusions
Patients with impaired renal function and HF show impaired cardiac sympathetic activity compared to HF patients with preserved renal function, and reduced eGFR estimated by EPI formula is a significant predictor of reduced late H/M evaluated by 123I-MIBG. Thus, in future studies, the combination of these two parameters might provide addictive prognostic information in HF patients.
Imaging cardiac sympathetic innervation with MIBG: linear conversion of the heart-to-mediastinum ratio between different collimators
