Fibromuscular Dysplasia in Acute Type A Aortic Dissection: A Common yet Underrecognized Vascular Phenotype in Women

Objectives: Fibromuscular dysplasia (FMD) is a non inflammatory, non atherosclerotic arterial disease characterized by multifocal arterial beading that predominantly affects women. Although FMD commonly involves the renal and carotid arteries, its relationship with acute type A aortic dissection (ATAAD) remains poorly understood. We investigated the proportion of patients with FMD among patients with ATAAD, focusing on sex based differences. Materials and Methods: Patients aged below 70 years with ATAAD and ECG triggered aortic CT angiography (CTA) were consecutively included in this retrospective single-center study. FMD was defined as multifocal arterial beading (string-of-beads appearance) in at least one vascular territory, according to international consensus criteria. The highest-quality CTA examination was evaluated by an experienced cardiovascular radiologist. All suspected FMD cases were independently reviewed by a second experienced cardiovascular radiologist, with the final diagnosis established by consensus. Proportions were reported with 95% confidence intervals and compared between sexes . Results: Of 214 patients screened, 200 were included (138 men and 62 women). FMD was confirmed in 18/200 patients (9%; 95% CI, 6 till 14%), none of whom had a prior FMD diagnosis. FMD was more frequent in women (12/62, 19%; 95% CI, 11 till 31%) than men (6/138, 4%; 95% CI, 2 till 9%; P<0.001). FMD predominantly involved the renal arteries. Additional carotid CTA was available in 49/200 patients (25%) and in 7/18 patients with FMD (39%); three of these seven patients had carotid FMD. Conclusion: FMD was observed in a substantial proportion of patients presenting with ATAAD, particularly women. These findings suggest that FMD is an underrecognized vascular phenotype in patients with ATAAD.