Deep Vascular Phenotyping in Patients With Renal Multifocal Fibromuscular Dysplasia

Arterial fibromuscular dysplasia is a nonatherosclerotic, noninflammatory vascular disease, whose pathophysiology is still unknown. We performed deep image-based vascular phenotyping of nonaffected arteries to look for systemic vascular alterations in fibromuscular dysplasia. This single center cross-sectional study included 50 patients with multifocal renal fibromuscular dysplasia, 50 hypertensive patients, and 50 healthy controls, matched for age, sex, and ethnicity; hypertensive patients were matched also for blood pressure. Brachial artery endothelium-dependent and endothelium-independent dilation were studied by echotracking. Aortic stiffness was assessed by carotid-to-femoral pulse wave velocity. We quantified the presence of supernumerary acoustic interfaces within the common carotid wall by the triple signal (TS) score. We plotted the Young incremental elastic modulus/stress curves for common carotid artery, derived from echotracking and tonometry. Patients with fibromuscular dysplasia had impaired endothelium-independent dilation (adjusted P=0.002), smaller brachial artery diameter but comparable endothelium-dependent dilation and aortic stiffness. The prevalence of TS score >6 was 56%, 40%, 24% in patients with fibromuscular dysplasia, hypertensives, and controls, respectively ( P=0.005). Fibromuscular dysplasia remained significantly associated with TS in the multiple regression model ( P=0.022). Impaired endothelium-dependent dilation was present only in patients with fibromuscular dysplasia, TS score >6 ( P=0.047). Incremental elastic modulus was higher for a given wall stress (80 kPa) in the presence of a TS score >6, especially in fibromuscular dysplasia. In conclusion, nonclinically affected large- and medium-sized arteries in patients with multifocal renal fibromuscular dysplasia exhibit a cluster of diffuse alterations in smooth muscle cell function, arterial geometry, wall characteristics, and mechanical properties. Clinical Trial Registration URL: http://www.clinicaltrials.gov . Unique identifier: NCT01935752.