Fibromuscular dysplasia (FMD) is a noninflammatory and nonatherosclerotic condition that affects the media of arterial walls, leading primarily to stenosis, as well as aneurysms, dissection, and arterial tortuosity.¹ As per the 2019 international consensus,¹ the diagnosis is based on the angiographic presence of either focal or multifocal FMD, the latter of which constitutes the classic “string of beads” appearance. It is important to note that the presence of aneurysm or dissection alone, without the typical FMD appearance on angiography is insufficient to make the diagnosis. Angiography can be performed invasively or using noninvasive methods (computed tomography angiography [CTA] or magnetic resonance angiography [MRA]). CTA has superior resolution and is typically preferred over MRA, but its disadvantages comprise radiation exposure and the need for iodinated intravenous contrast administration.

Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of myocardial infarction, particularly among women. Extracoronary vascular abnormalities (EVAs), including FMD, are commonly observed in patients with SCAD. Therefore, current recommendations of European and American societies advise screening for EVAs among individuals with a history of SCAD.^2,3 On the other hand, SCAD remains a rare occurrence among those with FMD. In the United States Registry for FMD, only 2.7% of patients with FMD had SCAD.⁴

In the study by Wiligórska et al,⁵ published in the current issue of Polish Archives of Internal Medicine, the authors retrospectively reviewed 109 consecutive patients with SCAD included in a multicenter registry coordinated by the National Institute of Cardiology, Warsaw, Poland, between 2018 and 2024. The presence of FMD was defined as per the international consensus criteria,¹ and screening was performed using CTA of the head, neck, chest, abdomen, and pelvis. Among the analyzed cohort of 109 patients (97.2% women) at a mean (SD) age of 44.6 (9.3) years, 32.1% had FMD, while 47.7% had EVAs. We congratulate the authors on this important work, which furthers our understanding of the true extent of extracoronary vascular involvement in the setting of SCAD.

The study confirms the high prevalence of EVAs and FMD among SCAD patients. In previous large contemporary series, the prevalence of EVAs among individuals with SCAD ranged between 36% and 71.6%, while the prevalence of FMD was between 30.7% and 62.7%.^6-10 As compared with a recent study from the Mayo Clinic,¹⁰ where extracoronary dissection was found in 12% of the patients and aneurysms in 16.5%, Wiligórska et al⁵ reported lower prevalence of dissection (5.5%) and higher prevalence of aneurysms (23.2%). Notably, the present cohort included relatively young patients (mean age, 44.6 [9.3] y), and 34.9% of them had hypertension. There were no significant differences in the prevalence of hypertension between the patients with and without FMD and those with and without EVAs.

The authors report several interesting observations. Firstly, pregnancy‑associated SCAD (P‑SCAD) occurred more commonly in the patients with FMD than in those without FMD (17.6% vs 4.2%; odds ratio, 4.9; 95% CI, 1.2–21.1; P = 0.04). This is in contrast to the findings of Tweet et al,¹¹ who reported that the individuals with P‑SCAD were less likely to have a diagnosis of FMD and EVA than those with non–pregnancy‑associated SCAD. It has been postulated that the drastic hormonal and hemodynamic shifts that occur during pregnancy and postpartum can lead to dissection even among women without an underlying arteriopathy, which is not supported by the findings of Wiligórska et al.⁵ Of note, the present study included only 9 patients with P‑SCAD. Secondly, cervical dissection was only seen in 5.5% of the population, while migraine, a hallmark symptom of cerebrovascular FMD, was reported in 58.5% of the patients with cervical FMD. This finding is in contrast to prior observations that patients with SCAD and migraines more often experience aneurysms, pseudoaneurysms, and dissections.¹² While genetic analysis was not performed in the given study, it would be interesting to determine whether the patients with SCAD and migraine carried the PHACTR1 single nucleotide polymorphism, a genetic susceptibility locus for FMD that is also associated with SCAD, cervical artery dissection, hypertension, and migraines.¹

Whole genome sequencing in a predominantly female population of SCAD patients has identified associations with extracellular matrix protein–encoding ADAMTS‑like protein 4, fibrillar collagens, such as COL3A, and FBN1, which are implicated in ectopia lentis, vascular Ehlers–Danlos syndrome, and Marfan syndrome, respectively.^13,14 However, as compared with FMD, heritable connective tissue disorders with a monogenic basis, such as Marfan syndrome or Ehlers–Danlos syndrome, are much less commonly observed and are only diagnosed in less than 5% of all patients with SCAD.¹⁵ Therefore, genetic testing of all patients with SCAD is low‑yield without high clinical suspicion based on a compatible syndrome, and routine testing is not recommended.^2,3 The current study echoes findings from other series, ^5-7,9,10 which showed an excess of EVAs that could not be explained by FMD alone. This raises the question of whether performing genetic testing among this enriched population of patients with SCAD and EVAs would be high‑yield in identifying genes associated with SCAD and arteriopathy, and shed further light on our understanding of SCAD pathophysiology.