The U. S. Registry for FMD began with seven U.S. centers enrolling patients and now involves 10 centers and has enrolled more than 500 patients. The first 339 enrollees included 44% who were patients at the Cleveland Clinic and 20% who were patients at Mount Sinai.
The average age of the enrolled patients at first symptom appearance was 47 years old; first diagnosis did not occur until an average of more than 4 years later, at an average age of 52 years old.
Vascular bed involvement among the first registry patients included one or both renal arteries in 69%, at least one extracranial carotid in 62%, vertebral arteries in 19%, and mesenteric arteries in 12%. At the time of enrollment, 7% of patients had a history of coronary artery disease and 10% had a history of stroke. The arterial fibrosis characteristic of FMD notably appears in portions of the renal and carotid arteries where atherosclerotic disease usually does not occur – in the distal renal artery and in the distal carotid, "higher than physicians usually look when they do carotid ultrasound" examinations, Dr. Olin said.
When he finds carotid fibrosis, Dr. Olin starts those patients on a daily aspirin, although the benefit of this strategy hasn’t been proven. If carotid lesions are substantial, treatment by angioplasty is possible; carotid stenting is not used on FMD patients, nor is endarterectomy, as there is no atherosclerotic plaque to remove, he said.
Dr. Olin said that he has been a consultant to Merck, and that he chairs the advisory board of the Fibromuscular Dysplasia Society of America. Dr. Lookstein said that he has been a consultant to Medrad and Cordis.