Prevalence and Nature of Extra-Coronary Fibromuscular Dysplasia in Patients with Spontaneous Dissection of Coronary Arteries

Details

Supervisors

Persu, Alexandre

Faculty

Faculté de médecine et médecine dentaire

Degree label

Master [180] en médecine

Abstract

Abstract Clinical Research’s Thesis: Prevalence and nature of extra-coronary fibromuscular dysplasia in patients with spontaneous dissection of coronary arteries Introduction: Spontaneous coronary artery dissection, often referred to as SCAD, is a relatively uncommon but increasingly recognized cause of myocardial infarction. It can occur in young patients, predominantly women, in the absence of atherosclerotic coronary artery disease and with few atherosclerotic risk factors. SCAD is frequently associated with fibromuscular dysplasia (FMD), an idiopathic, segmental, nonatherosclerotic and non-inflammatory disease of the musculature of small and medium-sized arteries which also occurs predominantly in middle-aged women. The main objectives of this study are to determine the incidence, clinical characteristics, associations of SCAD. As well as the prevalence, severity and the nature of extra-coronary FMD lesions and other vascular lesions in patients with SCAD in whom imaging of extra-coronary vascular beds is available. Methods: We conducted a retrospective search for all SCAD cases of female patients aged ≤ 50 y.o who presented an acute coronary syndrome (ACS) between 1997 and 2015 in the Cath Lab database of the Cliniques Universitaires Saint-Luc. In addition to this, interventional cardiologist from our institution were interrogated about previous diagnosis of SCAD they have made. We also added patients who presented acute coronary syndrome during 2015-2018 diagnosed SCAD after careful reviewing of their coronary angiograms. Patients with confirmed diagnosis of SCAD were contacted and were suggested to perform a vascular screening for extra-coronary vascular beds. They underwent recommended imaging (CTA/MRA) dedicated protocol which allows to visualize vasculature from neck to the pelvis through abdomen with specific search for vascular lesions while avoiding the invasiveness of catheter angiography. Results and Discussion: The diagnosis of SCAD was confirmed for 18 patients. The overall prevalence of SCAD in the study population of women ≤50 y.o. presenting an ACS between 1997-2015 was therefore 2.4%, this may be subject to underestimation. Mean age of patients in our cohort was 47 years and 83% were women, a third of our patients had one or no traditional cardiovascular risk factor and another third had only 2 risk factors. The most common angiographic SCAD appearance was a diffuse long and smooth stenosis (type 2 SCAD, in 86% of the cases). Consequently, if angiographers rely solely on radiolucent ‘flap’ and linear double lumen (typical type 1 SCAD) to make the diagnosis, they would possibly miss more than 3/4 of angiographic SCAD. The therapeutic management in our study was medical treatment alone in 16 patients (89%) and coronary stenting in 2 patients (11%). This is consistent with the recommendations in the literature. We were able to evaluate 11 out of 18 patients with a history of SCAD to detect fibromuscular dysplasia (FMD) and other arterial abnormalities in non-coronary vascular beds. In these 11 patients, multifocal FMD was present in 9 patients (82%) and the distribution of lesions was as follows: 6 (54%) had renal artery involvement of whom 3 also had either concomitant carotid, splenic or iliac FMD. 3 (36%) had neck arteries involvement alone. The FMD lesions present in our patients were exclusively multifocal FMD, alternating areas of stenosis and dilation (the so-called ‘string of beads’). These findings clearly show the improbability of a fortuitous association of SCAD and FMD. All 9 SCAD patients who were diagnosed with FMD are being clinically followed and those with significant dilations or stenosis were advised to undergo serial monitoring of their lesions to evaluate the progression and symptomatology associated. Conclusion: SCAD predominantly affects middle-aged but also older women. Most of SCAD patients present with type 2 angiographic SCAD. A substantial majority of patients who underwent vascular screening were diagnosed with extra-coronary FMD lesions; this confirms the idea that SCAD is part of a systemic vascular disease. Ultimately, forming larger cohorts with increased follow-up duration could help to elucidate the clinical implications of FMD, extra-coronary vascular abnormalities, and other risk factors in patients with SCAD.