The relationship between lung MIBG uptake and clinical response to renal denervation
Authors: Dalpiaz H , Leo A , Piludu S , Mori Ubaldini G , Sciarrone P , Buralli S , De Carlo M , Taddei S , Masi S , Gimelli A , Bacca A 
Published: October 2024

Abstract

Background
Renal denervation (RDN) reduces the sympathetic overdrive and can optimize blood pressure control in patients with difficult-to-treat hypertension (DTH). However, a substantial proportion of patients undergoing RDN do not show a clinical response to the procedure, making it critical to identify novel and more accurate predictors. The metaiodobenzylguanidine (MIBG) scintigraphy allows non-invasive assessment of sympathetic nerve activity. Yet, studies evaluating the heart and kidney MIBG uptake as predictors of clinical response to RDN provided conflicting results, and a comprehensive evaluation of the MIBG uptake in different organs of DTH patients undergoing RDN is lacking.

Purpose
To explore if a more comprehensive evaluation of MBG uptake in the kidneys, heart and lungs can predict the clinical response to RDN.

Methods
Eighteen patients with DTH underwent evaluation of their clinical and pharmacological history, office and ambulatory BP values and levels of cardiovascular risk factors. A rest echocardiography, carotid vascular ultrasound and MIBG scintigraphy were also performed before RDN. The patient’s pharmacological history and office and ambulatory BP values were re-evaluated after 3 months from RDN. We considered responders (R) those subjects with a significant reduction of the office BP values on stable BP-lowering treatment or a reduced burden of BP-lowering medications while maintaining optimal control of the office BP.

Results
Ten patients could be classified as R (1 woman, mean age 49±10 years), while 7 were non-responders (NR, 2 women, mean age 53±8 years). The reduction in office systolic and diastolic BP (baseline vs 3 months) was significantly larger in R vs NR (p=0.01 for both). The burden of BP-lowering medications after the procedure was reduced by 39% in R, compared to 2% in NR (p&lt;0.01). Responders had a higher baseline HR and prevalence of carotid atherosclerosis than NR (p&lt;0.05 for both). In early MIBG acquisitions, the lung/mediastinum ratio on both sides showed higher MIBG uptake in R vs NR (p&lt;0.05). There was a higher MIBG uptake in the right vs. left lung in the whole population and in R vs NR. In late acquisitions, only the left side showed a significant difference between R and NR (p&lt;0.05). The associations between the lung/mediastinum ratio MIBG uptake and response to RDN remained significant after adjusting for the baseline clinical predictors of the RDN response. All other MIBG scintigraphy parameters were similar between groups.

Conclusions
Our results suggest that RDN might be less effective in patients with an advanced burden of hypertension-mediated target organ damage and confirm a higher HR as a reliable predictor of the clinical response to the procedure. We also document a novel association between the lung/mediastinum ratio MIBG uptake and response to RDN that, if confirmed in future studies, might provide a novel marker to improve the selection of patients undergoing RDN.