CO-02: Prevalence and characteristics of coronary fibromuscular dysplasia in women aged <50 years admitted for an acute coronary event.

BACKGROUND: While "string-of-beads" coronary Fibromuscular Dysplasia (FMD) is rare, recent works suggest that Spontaneous Coronary Artery Dissection (SCAD) (a cardiac complication typically occurring in young women with few risk factors) is due to FMD in >80% of cases. Other aspects suggestive of coronary FMD include smooth narrowing, intramural hematoma and tortuosity. The management of FMD-related coronary events differs from that of atherosclerotic events: (I) conservative treatment is the preferred option; (II) screening for extra-coronary FMD lesions should be considered. Unfortunately, most interventional cardiologists are not familiar with this entity and many cases are overlooked. The aim of this study was to look for the prevalence and clinical presentation of coronary FMD in young women admitted to the Cath Lab for an acute coronary event.

METHODS: Coronary angiograms of all women aged <50 years admitted for an acute coronary event in our centre between 2000 and 2014 were retrieved and carefully reviewed by a senior interventional cardiologist. Cases suggestive of coronary FMD were compared with sex and agedmatched controls with atherosclerotic coronary heart disease admitted during the same period.

RESULTS: Aspects suggestive of coronary FMD were identified in 19/336 patients (mean age: 42±6.7 years). The predominant presentation was suspected coronary artery dissection (12 patients), either isolated (n=5) or associated with smooth narrowing (n=4), tortuosity (n=2) or intramural hematoma (n=1). In an additional 7 patients, aspects of smooth narrowing (n=5) or tortuous coronary vessels (n=2) were identified in the absence of direct evidence of dissection. Compared to 19 sex- and age-matched controls with atherosclerotic disease, the prevalence of diabetes was significantly lower (11 vs 58%, p=0.002), and the prevalence of smoking higher (63 vs 16%, p=0.003). No difference in the prevalence of hypertension (47 vs 32%, p=0.3) or dyslipidemia (42 vs 53%, p=0.5) was found.

CONCLUSIONS: In this retrospective series of women aged <50 years admitted for an acute coronary event, lesions suggestive of coronary FMD were found in 5.7% of cases. This prevalence is not negligible and may be substantially underestimated in the absence of IVUS or OCT. The high prevalence of smoking in the FMD group may reflect the known influence of smoking on FMD progression (Savard et al., Hypertension 2013). Despite its limitations, our study highlights the interest of a prospective registry of patients with coronary FMD and/or SCAD, based on strict diagnostic criteria.