CHICAGO – New data have shown that fibromuscular dysplasia is associated with high rates of dissection and/or aneurysm, and emerging recommendations call for routine imaging early on in the diagnosis of FMD to monitor for these vascular events, a researcher who developed those recommendations reported at a symposium on vascular surgery sponsored by Northwestern University.
“Given the very high rate of aneurysms in this population, it is now recommended that all patients with FMD should undergo at least one-time head-to pelvis imaging with CT angiography or MR angiography to screen for the presence of an aneurysm or to identify other areas of FMD involvement,” said Daniella Kadian-Dodov, MD, of Icahn School of Medicine at Mount Sinai in New York (J Am Coll Cardiol. 2016;68:176-85).
Dr. Daniella Kadian-Dodov
First described in 1938, FMD is a non-atherosclerotic, noninflammatory disease that had been thought to be a rare cause of renovascular hypertension with a classic “string-of-beads” appearance upon imaging, Dr. Kadian-Dodov noted. However, recent data from the Fibromuscular Dysplasia Society of America–sponsored U.S. registry has changed that thinking. “We now know it occurs more frequently in the carotid and renal arteries, although it has been observed in almost every artery,” she said. “The pathogenesis is still unknown but up to 10% of cases are familial.”
And manifestations of disease now extend beyond the “string-of-beads” appearance to include aneurysm, dissection, and arterial tortuosity, she said (Circulation. 2012;125:3182-90; Circulation. 2014;129:1048-78; J Am Coll Cardiol. 2016;68:176-85). The classification system for FMD has also undergone a recent change, according to Dr. Kadian-Dodov. “Traditionally, a histopathologic scheme was used to classify FMD,” she said. “Nowadays, fewer and fewer patients are undergoing surgical procedures, so the classification has changed to an angiographic system,” the most common of which is the American Heart Association system adopted in 2014 that distinguishes between multifocal, characterized by the classic “string-of-beads” appearance, and focal FMD with a single area of stenosis.
But the diagnosis of either variant of FMD is not exclusive. “Patients may have multiple areas of disease involvement and the same patient may have both focal and multifocal FMD findings,” Dr. Kadian-Dodov said.
The U.S. registry has helped clarify the thinking on FMD, Dr. Kadian-Dodov said. More than 1,400 patients are in the registry, 90% of whom are women with multifocal disease. The average age of onset of symptoms is 47 years, but 52 is the average age for diagnosis. “So these patients are experiencing several years delay to FMD diagnosis,” she said.
Manifestations depend on the vascular bed involved. “In the case of cervical artery FMD, headaches and pulsatile tinnitus are commonly reported, whereas with renal artery involvement hypertension is the most common symptom,” she said. A recent analysis showed 41.7% of the FMD population have either aneurysm and dissection or both (J Am Coll Cardiol. 2016;68:176-185).
But no specific guidelines for treatment of FMD yet exist, Dr. Kadian-Dodov said. “General guidelines should be applied for the management of dissection and aneurysm in patients with FMD,” she said. For patients with arterial dissection, that means conservative therapy comprising either anticoagulation or antiplatelet agents for 3-6 months followed by daily low-dose aspirin therapy. “Revascularization is rarely required for these patients,” she said. “Endovascular or surgical modalities should be reserved for those with continued ischemia despite conservative management or more complicated pseudoaneurysm formations.”
Daily aspirin therapy is likewise the recommendation for patients with cervical artery multifocal or focal FMD involvement without dissection or aneurysms. “We follow up with imaging every 6 months for 2 years,” Dr. Kadian-Dodov said. “If they’re stable, we switch over to annual surveillance; and if the patient has an aneurysm or dissection, that might alter the imaging and surveillance program.”
During angioplasty, determining the severity of stenosis upon visual inspection is difficult, especially in multifocal FMD. She advised measuring the gradient across the area of FMD involvement with a pressure wire to determine if angioplasty has adequately treated the lesion. “You should see obliteration of the gradient with successful treatment; you don’t have to target your therapy to a perfect angiographic result,” she said.
In patients with FMD and hypertension, she recommended renal artery angioplasty for hypertension of less than 5 years duration or in resistant or labile hypertension. “In this setting, stents are only reserved for complicated or refractory cases; angioplasty alone is sufficient,” Dr. Kadian-Dodov said. Cure rates decline with age, and hypertension in focal disease has a higher cure rate than does multifocal disease, she said (Hypertension. 2010;56:525-32).
Dr. Kadian-Dodov had no relevant financial relationships to disclose.