Fibromuscular Dysplasia: Diagnosis at Later Age Suggests Milder Course

When multifocal fibromuscular dysplasia (FMD) is diagnosed at an older age, its course appears to be more benign and less symptomatic than when recognized in middle age, concludes a new analysis of the U.S. Registry for Fibromuscular Dysplasia published in JAMA Cardiology.

“These findings confirm that FMD is not solely a disease of younger women but a vascular disorder that can emerge across the lifespan,” says the study’s senior author, Heather Gornik, MD, Section Head of Vascular Medicine at Cleveland Clinic. The multicenter study’s author team also included her section colleague Imad Bagh, MD.

First study of FMD in older patients

Most cases of FMD — an uncommon, nonatherosclerotic arterial disease that predominantly affects women — are diagnosed in middle age. Although presentation of FMD in older adults was previously recognized, the new study is the first to characterize the condition among patients 65 or older at the time of diagnosis, the authors note.

“We pursued this study because FMD’s natural history among such patients is not well understood,” observes Dr. Gornik, who in 2008 established Cleveland Clinic’s Fibromuscular Dysplasia Clinic as the first such clinic in the world.

She and her multicenter collaborators in the U.S. Registry for FMD — to which Cleveland Clinic is an enrolling center — evaluated baseline data for the 1,016 adult patients (95 percent female) enrolled in the registry as of late 2016.

Patients were categorized by age at FMD diagnosis — either 65 years or older (n = 170; 16.7 percent) or younger than 65 (n = 846; 83.3 percent). Mean age at diagnosis was 71.4 years in the former group and 49.9 years in the latter group.

The aim was to compare the prevalence of various characteristics — including specific symptoms, prior vascular events and prior vascular procedures — between the two groups.

Results: A few similarities, even more differences

There were no between-group differences in prevalence of renal artery involvement, number of arterial beds involved or the frequency of diagnosis of aneurysms.

In contrast, patients diagnosed at 65 or later differed significantly from their younger counterparts in several notable ways, including:

• Being more likely to be asymptomatic at diagnosis (4.2 percent vs. 1.4 percent)
• Having had fewer major vascular events (37.1 percent vs. 46.1 percent)
• Having undergone fewer therapeutic vascular procedures (18.5 percent vs. 33.1 percent)
• Having lower prevalence of headache (40.5 percent vs. 69.1 percent) and pulsatile tinnitus (30.0 percent vs. 44.6 percent)
• Having more frequent involvement of extracranial carotid arteries (87.0 percent vs. 79.4 percent)
• Being more apt to have hypertension (70.7 percent vs. 54.0 percent), likely due to essential hypertension

Reassurance is in order

“These findings suggest that patients diagnosed with FMD at an older age can be reassured that they’re more likely to have a milder disease course and will likely fare well with medical management alone in most cases,” says Dr. Gornik.

She notes that older patients’ lower likelihood of having headache and pulsatile tinnitus — the most common presenting symptoms among registry enrollees — could have contributed to these patients’ later age at diagnosis. It also suggests that elderly individuals may be underrepresented in the registry.

“FMD in older patients is often found when imaging studies are ordered to explore abnormal physical findings or incidentally on an imaging study done for another reason,” Dr. Gornik explains.

“This study underscores the need to consider FMD in the differential diagnosis, regardless of patient age, in the presence of classic symptoms like pulsatile tinnitus or resistant hypertension or when carotid bruits are found on physical examination,” she concludes.