Natural History of Cervical Artery Fibromuscular Dysplasia and Associated Neurovascular Events

Background and Purpose: Fibromuscular dysplasia (FMD) is a non-atherosclerotic arteriopathy most often affecting the carotid and renal arteries. In the United States Registry for FMD, 41.7% of patients experienced an aneurysm and/or dissection by the time of entry into the Registry. We sought to determine the occurrence of neurovascular events after FMD diagnosis and any changes on cervical artery imaging that may be attributable to FMD. Methods: Patients followed at the Mount Sinai Medical Center (US Registry for FMD enrollment center) with confirmed FMD and 1 cervical artery imaging study (at least ± 6 months from the baseline carotid duplex ultrasound CDU) between the years 2003 and 2015 were included. Medical records and cervical artery imaging (CDU, magnetic resonance angiogram MRA, and computed tomography angiogram CTA) were reviewed. New arterial dissection, aneurysm, transient ischemic attack, stroke, or new FMD findings were recorded. Results: Among 146 FMD patients with complete information, 52 (35.6%) had an aneurysm and 52 (35.6%) had a dissection. Mean clinical follow-up was 35.3 ± 25.3 months (range 5–153 months); patients underwent 4 ± 2.7 CDU (range 1–17); 86.3% had ≥1 neck MRA or CTA. After FMD diagnosis, 3 patients (2%) experienced a new carotid artery dissection; 1 patient experienced a stroke due to concomitant atherosclerosis. No new aneurysms occurred. In patients with cervical artery FMD, imaging findings remained stable throughout follow-up. No patient developed new cervical artery FMD findings on follow-up imaging. Conclusions: No new cervical artery FMD or aneurysm was observed on subsequent imaging. New carotid dissection was uncommon over a mean follow-up period of 35.3 ± 25.3 months and was the only non-atherosclerotic vascular event observed after FMD diagnosis.