Impact of aging on cardiac sympathetic innervation measured by I-mIBG imaging in patients with systolic heart failure.

Purpose: Sympathetic nervous system (SNS) hyperactivity is a salient characteristic of chronic heart failure (HF) and contributes to the progression of the disease. Iodine-123 meta-iodobenzylguanidine (I-mIBG) imaging has been successfully used to assess cardiac SNS activity in HF patients and to predict prognosis. Importantly, SNS hyperactivity characterizes also physiological ageing, and there is conflicting evidence on cardiac I-mIBG uptake in healthy elderly subjects compared to adults. However, little data are available on the impact of ageing on cardiac sympathetic nerve activity assessed by I-mIBG scintigraphy, in patients with HF.

Methods And Results: We studied 180 HF patients (age = 66.1 ± 10.5 years [yrs]), left ventricular ejection fraction (LVEF = 30.6 ± 6.3 %) undergoing cardiac I-mIBG imaging. Early and late heart to mediastinum (H/M) ratios and washout rate were calculated in all patients. Demographic, clinical, and echocardiographic data were also collected. Our study population consisted of 53 patients aged >75 years (age = 77.7 ± 4.0 year), 67 patients aged 62-72 years (age = 67.9 ± 3.2 years) and 60 patients aged ≤61 year (age = 53.9 ± 5.6 years). In elderly patients, both early and late H/M ratios were significantly lower compared to younger patients (p < 0.05). By multivariate analysis, H/M ratios (both early and late) and washout rate were significantly correlated with LVEF and age.

Conclusions: Our data indicate that, in a population of HF patients, there is an independent age-related effect on cardiac SNS innervation assessed by I-mIBG imaging. This finding suggests that cardiac I-mIBG uptake in patients with HF might be affected by patient age.