Fibromuscular dysplasia (FMD) is described as a ‘non-atherosclerotic, non-inflammatory disease of arterial walls’. It is an uncommon disease in the population but is found quite frequently in SCAD survivors. It occurs where there is abnormal cell growth in arteries and is most commonly found in renal (kidney), cervico-cephalic (neck-head) and iliac (pelvic) arteries.
Dr Tina Chrysochou discusses FMD
The Fibromuscular Dysplasia Society of UK and Ireland has lots of information for FMD patients.
FMD causes narrowing and/or enlargement of one or more medium-sized arteries. This can sometimes reduce blood flow and affect the function of organs.
FMD is more common in women (approx 80-90%) but does occur in men too. Current figures indicate that it mainly affects arteries leading to the kidneys, but is also found in arteries leading to the neck and brain, heart, abdomen, arms and legs.
The cause is unknown, but it is not an inflammatory condition, nor is it caused by atherosclerosis (furring of the blood vessels). It is not known whether there is a hormonal factor. Some people who have FMD are asymptomatic but others may have complications such as high blood pressure or artery dissections.
Watch Dr Tina Chrysochou discuss FMD here.
Researchers have not yet found the cause of FMD, but female hormones, genetics and trauma to artery walls may play a role. The Cleveland Clinic says about 7-11% of cases are inherited and about 25% of patients with FMD have had a family member with an aneurysm.
The European Society of Cardiology SCAD position paper 2018 says FMD has two sub-types: multifocal and focal (sometimes called unifocal).
In Focal FMD arteries have distinct focal lesions (damage) or tubular stenosis (narrowing).
In Multifocal FMD patients have multiple lesions and the artery has the appearance of a ‘string of beads’, caused by alternating areas of widening and narrowing.
Most SCAD survivors with FMD have no symptoms and require no treatment or follow-up imaging. A very small number of patients with SCAD and FMD will be symptomatic. These rare symptoms include:
FMD in the carotid or vertebral arteries – headaches, including migraines, a swooshing or pulsating noise in the ears, neck pain and lightheadedness. It is important to remember these are common symptoms and will not be due to FMD in most cases.
FMD in the renal arteries often causes high blood pressure and/or poor kidney function.
FMD of the mesenteric arteries (arteries to the intestines) may cause abdominal pain after eating and weight loss (this is very uncommon).
If you have no symptoms you will not need treatment. Indeed in most SCAD survivors FMD is an incidental finding and does not require either follow-up imaging or any specific treatment.
A very small number of SCAD patients may require surveillance imaging (for example for small arterial swellings called aneurysms).
In some patients with cervical FMD, antiplatelet medication (eg aspirin) may be prescribed to prevent blood clots.
If you have high blood pressure you may need to take blood pressure medication. Very occasionally high blood pressure in patients with renal FMD may not respond to treatment and specific treatment to the artery may be needed. In the context of SCAD with FMD this is extremely rare.
If you have frequent headaches, especially migraines you may be offered medication to help.
FMD may be found during an X-ray or scan for another problem, and imaging such as an angiogram, MRA (magnetic resonance angiography) or CTA (computed tomography angiography) can confirm a diagnosis.
Experts esimate that a third to half of SCAD patients will also be diagnosed with FMD. Some studies have reported FMD in 11-86% of SCAD patients. The range narrows to 41-86% after excluding three studies where less than 50% of patients were screened. Prevalence of FMD may differ depending on the proportion of patients screened and the screening method used. FMD may be more frequent in SCAD patients with more tortuous (curvy/winding) coronary arteries.
The most important thing to understand is that although FMD is quite common in SCAD patients, it is rarely of clinical importance. If you are found to have FMD, discuss it with your doctors but in most cases this is not something to worry about. (Source: European Society of Cardiology SCAD position paper 2018)
We asked if SCAD could be FMD of the heart arteries. SCAD expert Dr David Adlam told us that recent data from genetic studies suggests there’s an overlap (the first common variant found also occurs in FMD and migraines) but they don’t seem to have the same genetic signature. So they are more likely to be related and overlapping rather than the same thing. Patients with primary FMD (FMD as a primary diagnosis) don’t seem to have SCAD – SCAD seems to be rare in that cohort.
FMD info from the UK Kidney Association
Clinical info from the UK Kidney Association
Cleveland Clinic information on FMD
Brain Facts information on FMD
National Organisation for Rare Diseases (NORD) information on FMD
Hypertension magazine Revisiting Fibromuscular Dysplasia
First International Consensus on the diagnosis and management of fibromuscular dysplasia
Fibromuscular Dysplasia Society UK & Ireland
Fibromuscular Dysplasia Society UK & Ireland Youtube channel
FMD UK & Ireland Facebook group
Fibromuscular Dysplasia Patient Association Belgium
FMD-BE’s closed Facebook group
Fibromuscular Dysplasia Society of America
Video from first FMD Information Day January 2019 What is FMD?
Conference 2023 Dr Tina Chrysochou discusses FMD
Dr Tina Chrysochou discusses the UK FMD Study (2022)
Dr Tina Chrysochou discusses FMD (2021)
Dr Aine De Bhailis (Renal Consultant, Salford Royal Hospital) explains FMD (2022)
Dr David Adlam discusses FMD (2022)
FMD Q&A (Dec 2022)
Dr Abi Al-Hussaini on FMD (2018)
FAQs
Fibromuscular dysplasia (FMD) is described as a ‘non-atherosclerotic, non-inflammatory disease of arterial walls’. It is an uncommon disease in the population but is found quite frequently in SCAD survivors. It occurs where there is abnormal cell growth in arteries and is most commonly found in renal (kidney), cervico-cephalic (neck-head) and iliac (pelvic) arteries.
FMD causes narrowing and/or enlargement of one or more medium-sized arteries. This can sometimes reduce blood flow and affect the function of organs.
FMD is more common in women (approx 80-90%) but does occur in men too. Current figures indicate that it mainly affects arteries leading to the kidneys, but is also found in arteries leading to the neck and brain, heart, abdomen, arms and legs.
The cause is unknown, but it is not an inflammatory condition, nor is it caused by atherosclerosis (furring of the blood vessels). It is not known whether there is a hormonal factor. Some people who have FMD are asymptomatic but others may have complications such as high blood pressure or artery dissections.
Many SCAD patients are also diagnosed with Fibromuscular Dysplasia (FMD). Studies have reported FMD in SCAD patients in 11-86% of patients. The range narrows to 41-86% after excluding three studies where less than 50% of patients were screened. Prevalence of FMD may differ depending on the proportion of patients screened and the screening method used. FMD may be more frequent in SCAD patients with more tortuous (curvy/winding) coronary arteries. The most important thing to understand is that although FMD is quite common in SCAD patients, it is rarely of clinical importance. If you are found to have FMD, discuss it with your doctors but in most cases this is not something to worry about. (Source: European Society of Cardiology SCAD position paper 2018)
We asked if SCAD could be FMD of the heart arteries. SCAD expert Dr David Adlam told us that recent data from genetic studies suggests there’s an overlap (the first common variant found also occurs in FMD and migraines) but they don’t seem to have the same genetic signature. So they are more likely to be related and overlapping rather than the same thing. Patients with primary FMD (FMD as a primary diagnosis) don’t seem to have SCAD – SCAD seems to be rare in that cohort.
Associated Conditions...
Fibromuscular Dysplasia
Information about this uncommon condition that is found quite frequently in SCAD patients
Ehlers-Danlos Syndromes
Information about this connective tissue disorder a small number of SCAD patients also have
Marfan Syndrome
Information about this condition that a very small number of SCAD patients have
Loeys Dietz Syndrome
Information about this genetic condition that has a link with SCAD
Heart Failure
Explanation of symptoms, treatment and living with heart failure, which some patients develop after their SCAD