1.5 Deep Vascular Phenotyping in Patients with Fibromuscular Dysplasia

Abstract

Background

Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory vascular disease involving medium-sized muscular arteries, whose pathophysiology is still unknown.

Objectives

We aimed at identifying systemic vascular alterations in usually non-affected arteries of patients with multifocal renal FMD by a deep imaging-based phenotyping.

Methods

This cross-sectional study included FMD patients (n = 50, 84% hypertensives), age-, sex and BP-matched patients with primary hypertension (PH, n = 50) and healthy normotensive subjects (HS, n = 50). Brachial artery (BA) endothelium-dependent flow-mediated dilation (EDD) and endothelium-independent vasodilation (EID) were studied. Aortic stiffness was assessed by carotid-to-femoral pulse wave velocity (PWV). We quantified abnormal echographic patterns in the common carotid wall by the triple signal score. Common carotid Young’s incremental elastic modulus (Einc)/ stress curves were also plotted.

Results

FMD patients had impaired EID compared to PH and HS (p = 0.008, after adjustment for confounders p = 0.002), smaller BA diameter but comparable EDD and PWV. The prevalence of triple signal score >6 was 56%, 40%, 24% in FMD, PH and HS respectively (p = 0.005). FMD, but not PH, was significantly associated with triple signal (beta = 0.143, p = 0.022, r2 = 0.058). Impaired EDD was only present in FMD patients with triple signal score>6 (p for interaction = 0.047). For a given stress value of 80 kPa, Einc was higher in the presence of a triple signal score >6, especially in FMD patients.

Conclusions

Non-affected musculo-elastic and muscular arteries in patients with multifocal renal FMD exhibit a cluster of functional and structural abnormalities, while elastic arteries are preserved. Triple signal in FMD may identify a distinct vascular phenotype.