Spontaneous Coronary Artery Dissection and Fibromuscular Dysplasia: Vasculopathies With a Predilection for Women

Attitudes to and Attendance at Cardiac Rehabilitation After Spontaneous Coronary Artery Dissection

PURPOSE

Cardiac rehabilitation (CR) is standard care for patients after a heart event, including acute myocardial infarction. However, the uptake and relevance of traditional CR after acute myocardial infarction due to spontaneous coronary artery dissection (SCAD) has not been extensively investigated. The present study investigated attitudes toward CR, identified the rate and correlates of CR attendance, and examined the reasons for CR non-attendance after SCAD.

METHODS

Online focus groups (n = 30) explored attitudes toward and experiences of CR of survivors of SCAD, with data analyzed thematically according to recommended guidelines. An online survey (n = 310) then investigated rates of CR attendance and reasons for non-attendance. Correlates of CR attendance were identified using bivariate and multivariable analyses.

RESULTS

Thematic analysis revealed 5 themes in the perceptions of CR of survivors of SCAD: (1) lack of relevance of CR educational content; (2) lack of identification with typical CR attendees; (3) lack of CR health professional knowledge and skills; (4) preference for SCAD-specific CR; and (5) benefits of CR. The survey demonstrated a CR attendance rate of 63% (73% among those referred). The correlates of CR attendance were mid-level education and self-reported lifetime anxiety. Among attendees, the correlates of attending fewer sessions were having a more recent SCAD, not having lifetime anxiety, and not knowing other survivors of SCAD. Reported reasons for non-attendance mirrored qualitative themes identified.

CONCLUSION

While the survey demonstrated high CR attendance, perceptions that CR was unnecessary and irrelevant after SCAD were evident, often based on health professional advice. The findings add to the growing literature highlighting a need for appropriate support for survivors of SCAD.

Spontaneous Coronary Artery Dissection and a Family History of Aortic Dissection: A Genetic Association Study

BACKGROUND

Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of acute coronary syndrome or sudden cardiac death, primarily affecting relatively young women (median age, 51 years) without typical cardiovascular risk factors. SCAD has a genetic component, with genome-wide association studies identifying multiple risk loci. Thoracic aortic dissection (type A) shares some genetic overlap with SCAD, suggesting potential common predispositions.

METHODS

We performed genetic screening or whole-genome sequencing of 17 patients with SCAD (94% women) with a first- or second-degree relative (89% men) affected by aortic dissection (AD). We assessed rare variants in candidate genes and genome-wide using the American College of Medical Genetics and Genomics criteria. Polygenic risk scores were calculated to assess genetic risk for SCAD, fibromuscular dysplasia, AD, and abdominal aortic aneurysm in patients with SCAD, relatives with AD, and controls.

RESULTS

Whole-genome sequencing identified pathogenic or likely pathogenic variants in SMAD3, CBS, and COL3A1 in 3 SCAD cases. Additionally, 4 variants of uncertain significance were found in candidate genes. Polygenic risk scores for SCAD were significantly associated with increased odds of SCAD in probands versus controls (odds ratio, 1.79 [95% CI, 1.08-2.99]; P=0.024).

CONCLUSIONS

Our study supports a complex genetic landscape underlying SCAD, implicating rare monogenic pathogenic variants and polygenic risk. We identified pathogenic variants in patients with SCAD with a family history of AD, highlighting potential genetic links between these vascular disorders. The findings underscore the importance of genetic screening in patients with SCAD with a history of AD to identify individuals at risk and guide preventive strategies.

Screening for fibromuscular dysplasia after spontaneous coronary artery dissection unmasks a massive right renal artery aneurysm requiring ex vivo surgical resection and autotransplantation

Spontaneous coronary artery dissection (SCAD) is an increasingly recognised cause of acute coronary syndrome predominantly affecting women (>90% of cases) that is frequently associated with other arteriopathies, such as fibromuscular dysplasia (FMD) and migraine. We present a case of multi-vessel SCAD in a woman in her 40s presenting with myocardial infarction in whom incidental widespread FMD was found, including a massive right renal artery aneurysm requiring ex vivo resection, repair and autotransplantation. The case underscores the need for routine angiographic screening for FMD, which has a shared genetic risk with SCAD, and is associated with aneurysms, stenoses and hypertension.

Spontaneous coronary and vertebral artery dissection in early pregnancy

A nulliparous woman presented to the hospital at 11 weeks' gestation with acute onset chest pain, non-specific ECG changes and mildly elevated cardiac enzymes despite having no cardiac risk factors. She re-presented 4 days later with chest and arm pain, and ECG changes consistent with a posteroinferior ST elevation myocardial infarction. She was diagnosed with a spontaneous coronary artery dissection on a coronary angiogram and a right vertebral artery dissection on CT scan. Subsequent extension of the coronary dissection 4 days later required a coronary artery bypass graft. The patient elected to continue the pregnancy, while acknowledging the maternal and fetal risks. At 28 weeks' gestation, the fetus had dilated small bowel loops on the obstetrical ultrasound. At 33+4 weeks' gestation, a 2154 g male infant was born by emergency Caesarean section for non-reassuring cardiotocography. The infant had jejunal atresias, requiring bowel resection and primary anastomoses.

It's Probably Just Heart Burn! A Case of Pregnancy-Associated Spontaneous Coronary Artery Dissection

Pregnancy-associated spontaneous coronary artery dissection (P-SCAD) poses a rare yet critical concern among postpartum individuals, increasingly recognized as a significant trigger for acute myocardial infarction. Timely identification, accurate diagnosis, and prompt treatment are paramount for clinicians confronted with this condition. Patients with P-SCAD commonly manifest signs and symptoms akin to acute coronary syndrome but have different etiology and treatment. SCAD is defined as a non-traumatic, non-iatrogenic separation of the coronary artery wall, not associated with atherosclerosis. The predominant mechanism of myocardial injury is coronary artery obstruction caused by an intramural hematoma or intimal disruption compromising the lumen at the site of dissection. Diagnosis is made with a comprehensive history and physical examination, cardiac biomarkers, a 12-lead ECG, transthoracic echocardiogram, and confirmed with coronary angiography. Stable patients are managed medically, while more severe cases may require additional intervention.

Spontaneous coronary artery dissection and fibromuscular dysplasia: insights into recent developments

Spontaneous coronary artery dissection (SCAD), an uncommon cause of acute coronary syndrome, continues to be a poorly understood disease predominantly affecting females. It is characterized by an abrupt separation in the coronary arterial wall due to intramural bleeding. Fibromuscular dysplasia (FMD) is a non-atherosclerotic arteriopathy manifesting in medium and small-sized arteries. It is a concomitant disease found among SCAD patients. In some studies, FMD prevalence in SCAD patients ranges between 25%-86%, which can be explained through varying screening techniques or modalities. The potential association has been elucidated in some studies; notably, not only has a genetic link been recently delineated between SCAD and FMD, but there is data to suggest that FMD not only can predispose to SCAD but can also be a potential predictor of its recurrence. However, a clear-cut correlation between the two has still not been established due to conflicting reports in the literature. To further dive into its pathology, it is crucial to highlight the importance of systematic screening in SCAD in order to identify associated risk factors and to be used as a method of FMD detection in such patients. Together, the two pathologies pose unique challenges in understanding its pathophysiology, diagnosis and management, as there is no clear evidence of a definitive treatment plan for patients with SCAD and FMD. A potentially beneficial modality of management is physical exercise, which is currently understudied in the long-term approach to treatment for patients with concomitant SCAD and FMD. Limited research in this field brings disadvantages to the understanding of the association between these two diseases, in order to give rise to better management recommendations. This mini-review aims to highlight the recent developments in the association between SCAD and FMD, its potential genetic association and some insights in screening, diagnosis, and management.

Patients' perspective of quality-of-care and its correlation to quality-of-life following spontaneous coronary artery dissection

AIMS

Spontaneous coronary artery dissection (SCAD) is an under-recognized cause of myocardial infarction. We aimed to investigate SCAD survivors' perceptions of their quality-of-care and its relationship to quality-of-life.

METHODS AND RESULTS

An anonymous survey was distributed online to SCAD survivors involved in Australian SCAD support groups, with 172 (95.3% female, mean age 52.6 ± 9.2 years) participants in the study. The survey involved assessment of quality-of-life using a standardized questionnaire (EQ-5DTM-3L). Respondents rated the quality-of-care received during their hospital admission for SCAD with a median of 8/10 [interquartile range (IQR) 7-10]. Respondents ≤ 50 years vs. >50 years were more likely to perceive that their symptoms were not treated seriously as a myocardial infarction (χ2 = 4.127, df = 1, P < 0.05). Participants rated clinician's knowledge of SCAD with a median of 4/10 (IQR 2-8) and 7/10 (IQR 3-9) for Emergency and Cardiology clinicians, respectively (P < 0.05). The internet was the most selected source (45.4%) of useful SCAD information. The mean EQ-5DTM summary index was 0.79 (population norm 0.87). A total of 47.2% of respondents reported a mental health condition diagnosis, with 36% of these diagnosed after their admission with SCAD. Quality-of-life was significantly associated with perceived quality-of-care: EQ-5DTM index/(1-EQ-5DTM index) increased by 13% for each unit increase in quality-of-care after adjusting for age and comorbidities (P < 0.001).

CONCLUSION

While SCAD survivors rated their overall hospital care highly, healthcare providers' knowledge of SCAD was perceived to be poor, and the most common source of SCAD information was the internet. Mental health conditions were common, and a significant association was observed between perceived quality-of-care and SCAD survivors' quality-of-life.

Cardiovascular multimodality imaging in women: a scientific statement of the European Association of Cardiovascular Imaging of the European Society of Cardiology

Cardiovascular diseases (CVD) represent an important cause of mortality and morbidity in women. It is now recognized that there are sex differences regarding the prevalence and the clinical significance of the traditional cardiovascular (CV) risk factors as well as the pathology underlying a range of CVDs. Unfortunately, women have been under-represented in most CVD imaging studies and trials regarding diagnosis, prognosis, and therapeutics. There is therefore a clear need for further investigation of how CVD affects women along their life span. Multimodality CV imaging plays a key role in the diagnosis of CVD in women as well as in prognosis, decision-making, and monitoring of therapeutics and interventions. However, multimodality imaging in women requires specific consideration given the differences in CVD between the sexes. These differences relate to physiological changes that only women experience (e.g. pregnancy and menopause) as well as variation in the underlying pathophysiology of CVD and also differences in the prevalence of certain conditions such as connective tissue disorders, Takotsubo, and spontaneous coronary artery dissection, which are all more common in women. This scientific statement on CV multimodality in women, an initiative of the European Association of Cardiovascular Imaging of the European Society of Cardiology, reviews the role of multimodality CV imaging in the diagnosis, management, and risk stratification of CVD, as well as highlights important gaps in our knowledge that require further investigation.

Epidemiology of Spontaneous Cervical Artery Dissection: Population-Based Study

BACKGROUND

Cervical artery dissection (CeAD) represents up to 15% to 25% of ischemic strokes in people under the age of 50 years. Noninvasive vessel imaging is increasingly used in clinical practice, but the impact on the frequency of detection of CeAD is unknown. In 2006, the yearly incidence rate of CeAD was estimated at 2.6 per 100 000 person-years, but the current incidence is unknown.

METHODS

In this population-based retrospective observational cohort study, we utilized the resources of the Rochester Epidemiology Project to ascertain all adult residents of Olmsted County, MN, diagnosed with internal carotid artery dissection and common carotid artery dissection or vertebral artery dissection from 2002 to 2020. Patients with only intracranial involvement or CeAD following major trauma were excluded. Age-adjusted sex-specific and age- and sex-adjusted incidence rates were estimated using the US White 2010 decennial census, with rates expressed per 100 000 person-years. We assessed longitudinal trends by dividing the data into 5-year time intervals, with the last being a 4-year interval.

RESULTS

We identified 123 patients with a diagnosis of CeAD. There were 63 patients with internal carotid artery dissection, 54 with vertebral artery dissection, 2 with concurrent internal carotid artery dissection and vertebral artery dissection, and 4 with common carotid artery dissection. There were 63 (51.2%) female patients and 60 (48.8%) male patients. The average age at diagnosis was 50.2 years (SD, 15.1 [95% CI, 20.1-90.5] years). The incidence rate of spontaneous CeAD encompassing all locations was 4.69 per 100 000 person-years (2.43 for internal carotid artery dissection and 2.01 for vertebral artery dissection). The incidence rate increased from 2.30 per 100 000 person-years from 2002 to 2006 to 8.93 per 100 000 person-years from 2017 to 2020 (P<0.0001). The incidence rate for female patients rose from 0.81 per 100 000 person-years from 2002 to 2006 to 10.17 per 100 000 person-years from 2017 to 2020.

CONCLUSIONS

The incidence rate of spontaneous CeAD increased nearly 4-fold over a 19-year period from 2002 to 2020. The incidence rate in women rose over 12-fold. The increase in incidence rates likely reflects the increased use of noninvasive vascular imaging.

What Is New in Spontaneous Coronary Artery Dissection?

Spontaneous coronary artery dissection (SCAD) is a condition that leads to tearing of the coronary vessel wall in the absence of trauma, iatrogenic injury, or atherosclerosis. SCAD is an important cause of myocardial infarction in young women, leading to significant cardiovascular morbidity and mortality. Within cohorts of women aged around 50 years on average, who experience acute coronary syndrome, the prevalence of SCAD is 22.5%- 35%. Over the past decade, SCAD research has expanded rapidly, leading to improved understanding of this condition. In this review, we provide a summary of the current body of knowledge, highlight areas of ongoing research, and identify existing knowledge gaps. Specifically, we provide a focused update on the pathogenesis of SCAD, including genetic and associated conditions, clinical presentation and diagnosis, prognosis, and short-term and long-term management. Highlighted areas include the following: insights from recent genome-wide association studies; intracoronary imaging for the diagnosis of SCAD; the role of cardiac computed tomography angiography to assess for vessel healing; revascularization strategies and challenges; cardiogenic shock in SCAD; and the increasingly recognized burden of anxiety, depression, and posttraumatic stress disorder among SCAD patients.

Assessment of extra-coronary peripheral arteriopathy in spontaneous coronary dissection: state of the art in non-invasive imaging techniques and future perspectives

Spontaneous coronary artery dissection (SCAD) has been recognized as an important cause of acute coronary syndrome in women ≤ 50 years old, and up to 43% of pregnancy-associated myocardial infarction. SCAD has a strong association with extra-coronary arteriopathies, including either more common entities such as dissections, intracranial or other aneurysms, and extra-coronary and coronary arterial tortuosity or less common inherited vascular disorders such as Ehlers-Danlos syndrome, Marfan syndrome, and Loeys-Dietz syndrome, leading to the conclusion that systemic arterial disorders may underlie SCAD. Fibromuscular dysplasia is the most common extra-coronary vascular abnormality identified among these patients, also sharing a common genetic variant with SCAD. The American Heart Association, in a scientific statement regarding the management of SCAD, recommends that patients with SCAD should undergo additional evaluation with imaging techniques including either computed tomography angiography (CTA) or magnetic resonance angiography (MRA). MRA has been shown to have sufficient diagnostic accuracy in identifying extra-coronary arterial abnormalities, almost equal to CTA and conventional angiography. The aim of this review is to appraise the most recent important evidence of extra-coronary arteriopathy in the setting of SCAD and to discuss the strengths and weaknesses of various non-invasive imaging methods for screening of extra-coronary arteriopathies in patients with SCAD.

Prevalence of Anxiety, Depression, and Distress in SCAD and Non-SCAD AMI Patients: A Comparative Study

PURPOSE

Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of acute myocardial infarction (AMI), particularly in younger women without classic cardiac risk factors. Spontaneous coronary artery dissection is considered to be particularly stressful; however, few studies have quantified SCAD survivor stress levels. This study compared anxiety, depression, and distress levels in SCAD and non-SCAD AMI patients.

METHOD

A sample of 162 AMI (35 [22%] SCAD) patients was recruited from hospitals and via social media, in Australia and the United States. All had had their AMI in the past 6 mo. Participants completed an online questionnaire comprising the Generalized Anxiety Disorder-2 (GAD2), Patient Health Questionnaire-2 (PHQ2), Kessler-6 (K6), and Cardiac Distress Inventory (CDI). T-tests, χ 2 tests, Mann-Whitney tests, and analysis of covariance were used to compare SCAD and non-SCAD samples. Logistic regression was used to identify the unique predictors of anxiety, depression, and distress, controlling for relevant confounders.

RESULTS

Patients with SCAD were more commonly female and significantly younger than non-SCAD patients. Patients with SCAD scored significantly higher on the GAD2, PHQ2, K6, and CDI and a significantly larger proportion was classified as anxious, depressed, or distressed using these instruments. In logistic regression, together with mental health history, having had a SCAD-AMI predicted anxiety, depression, and distress, after controlling for female sex, younger age, and other confounding variables.

CONCLUSION

This study supports the view that anxiety, depression, and distress are more common after SCAD-AMI than after traditional AMI. These findings highlight the psychosocial impacts of SCAD and suggest that psychological support should be an important component of cardiac rehabilitation for these patients.

Type I Non-ST Segment Elevation Myocardial Infarction (NSTEMI) Followed by Type II in a Young Patient With Fibromuscular Dysplasia (FMD) Presented With Hypertensive Emergency: A Case Report

This article presents a case report highlighting the association between fibromuscular dysplasia (FMD) and acute myocardial infarction in a 25-year-old female patient with multiple cardiovascular comorbidities. Initially presenting with a hypertensive emergency, the patient subsequently developed acute coronary syndrome. MRI revealed irregular narrowing of the bilateral renal arteries, consistent with a diagnosis of FMD. Further evaluation through cardiac catheterization confirmed 95% stenosis of the mid-circumflex artery, necessitating percutaneous coronary intervention (PCI). Fibromuscular dysplasia has been frequently reported in conjunction with coronary artery dissection leading to acute coronary syndrome, especially in young females. Here, we describe the case of FMD without any coronary artery dissection. The presence of FMD highlights the need for comprehensive evaluation and management in patients with multiple cardiovascular risk factors. The recognition of FMD as an underlying pathology in acute myocardial infarction is crucial for appropriate intervention strategies. In this particular case, PCI was successfully performed to address the significant stenosis of the mid-circumflex artery. These findings emphasize the importance of considering FMD as a potential contributing factor in young patients presenting with acute coronary syndrome, particularly in the context of renal artery involvement. Increased awareness among healthcare providers regarding the association between FMD and acute myocardial infarction can aid in prompt diagnosis, appropriate management, and improved patient outcomes.

Typical clinical presentation of acute myocardial infarction and confusing coronary angiography: A case report and literature review of coronary embolism

RATIONALE

The purpose of this article is to discuss the characteristics, diagnosis, treatment, and outcomes of cases of multiple coronary embolism (CE) highly suspected to be caused by a dislodged aneurysm of the ventricular membranous septum (AVMS) thrombus.

PATIENT CONCERNS

A 35-year-old man was rushed to the Chest Pain Center of Taicang TCM Hospital Affiliated to Nanjing University of Chinese Medicine for sudden onset of chest pain. The patient had severe and persistent chest pain without relief, accompanied by sweating throughout the body.

DIAGNOSIS

An electrocardiogram showed ST-segment elevation in the inferior wall leads, and blood tests suggested elevated troponin I levels. The initial diagnosis was acute ST-segment elevation myocardial infarction. Emergency coronary angiography revealed complete occlusion of the first diagonal branch, thrombolysis in myocardial infarction grade 0 flow, and smooth remaining vessels. Complete occlusion of the left anterior descending artery unexpectedly occurred during interventional treatment. Postoperative cardiac ultrasonography revealed the presence of a thrombus within the AVMS and in the apical portion of the heart. The final diagnosis was a CE.

INTERVENTIONS

Intraoperatively, the diagonal branch occluded segment was dilated with a balloon and intracoronary administration of tirofiban and nitroglycerin. Postoperatively, antithrombotic therapy (aspirin, clopidogrel, and rivaroxaban) was administered.

OUTCOMES

Ten days after admission, a repeat coronary angiography showed complete restoration of left anterior descending artery flow on its own, balloon dilation was again performed on the diagonal branch, and flow was restored to thrombolysis in myocardial infarction grade 1. Six months later, the intracardiac thrombus disappeared on repeat cardiac ultrasound.

LESSONS

AVMS is a potential source of embolism in patients with CE. CE has features that distinguish it from atherosclerosis, and a timely and correct diagnosis can help improve patient clinical outcomes.

Arterial dissections: Common features and new perspectives

Arterial dissections, which involve an abrupt tear in the wall of a major artery resulting in the intramural accumulation of blood, are a family of catastrophic disorders causing major, potentially fatal sequelae. Involving diverse vascular beds, including the aorta or coronary, cervical, pulmonary, and visceral arteries, each type of dissection is devastating in its own way. Traditionally they have been studied in isolation, rather than collectively, owing largely to the distinct clinical consequences of dissections in different anatomical locations - such as stroke, myocardial infarction, and renal failure. Here, we review the shared and unique features of these arteriopathies to provide a better understanding of this family of disorders. Arterial dissections occur commonly in the young to middle-aged, and often in conjunction with hypertension and/or migraine; the latter suggesting they are part of a generalized vasculopathy. Genetic studies as well as cellular and molecular investigations of arterial dissections reveal striking similarities between dissection types, particularly their pathophysiology, which includes the presence or absence of an intimal tear and vasa vasorum dysfunction as a cause of intramural hemorrhage. Pathway perturbations common to all types of dissections include disruption of TGF-β signaling, the extracellular matrix, the cytoskeleton or metabolism, as evidenced by the finding of mutations in critical genes regulating these processes, including LRP1, collagen genes, fibrillin and TGF-β receptors, or their coupled pathways. Perturbances in these connected signaling pathways contribute to phenotype switching in endothelial and vascular smooth muscle cells of the affected artery, in which their physiological quiescent state is lost and replaced by a proliferative activated phenotype. Of interest, dissections in various anatomical locations are associated with distinct sex and age predilections, suggesting involvement of gene and environment interactions in disease pathogenesis. Importantly, these cellular mechanisms are potentially therapeutically targetable. Consideration of arterial dissections as a collective pathology allows insight from the better characterized dissection types, such as that involving the thoracic aorta, to be leveraged to inform the less common forms of dissections, including the potential to apply known therapeutic interventions already clinically available for the former.

Psychosocial impacts of spontaneous coronary artery dissection: A qualitative study

Spontaneous coronary artery dissection (SCAD) is an increasingly recognised cause of acute myocardial infarction, particularly in younger women without classic cardiac risk factors. While recent quantitative studies have noted high anxiety and depression in SCAD survivors, the full range and extent of psychosocial impacts of SCAD is unknown. The present study used a qualitative approach to investigate the psychosocial impacts of SCAD in Australian SCAD survivors. Focus group participants were recruited as part of a larger study of SCAD survivors currently being undertaken by the Victor Chang Cardiac Research Institute. Thirty SCAD survivors participated in one of seven online focus groups, conducted using a semi-structured format. Focus group duration was 1.5 hours. Each was digitally recorded and transcribed. Data were analyzed thematically according to recommended guidelines. One over-arching theme, five main themes and 26 sub-themes were identified. The over-arching theme related to lack of information, while the five main themes related to emotional impacts, issues with self-management, issues with family, impacts on work life, and the need for psychosocial support. The ‘emotional impacts’ theme comprised 11 sub-themes, namely shock and disbelief, confusion and uncertainty, unfairness, fear and anxiety, loss and grief, isolation and loneliness, guilt, invalidation and embarrassment, depression, vulnerability, and frustration. Findings are discussed in light of relevant psychological theories. This qualitative study extends previous quantitative investigations of SCAD survivors by providing an in-depth understanding of the complex, inter-related and highly distressing impacts of SCAD. The findings point to the urgent need for a coherent approach to information provision, the development and delivery of SCAD-specific cardiac rehabilitation programs, and the provision of psychosocial support programs for SCAD survivors.

Exploring the Genetic Architecture of Spontaneous Coronary Artery Dissection Using Whole-Genome Sequencing

BACKGROUND

Spontaneous coronary artery dissection (SCAD) is a cause of acute coronary syndrome that predominantly affects women. Its pathophysiology remains unclear but connective tissue disorders (CTD) and other vasculopathies have been observed in many SCAD patients. A genetic component for SCAD is increasingly appreciated, although few genes have been robustly implicated. We sought to clarify the genetic cause of SCAD using targeted and genome-wide methods in a cohort of sporadic cases to identify both common and rare disease-associated variants.

METHODS

A cohort of 91 unrelated sporadic SCAD cases was investigated for rare, deleterious variants in genes associated with either SCAD or CTD, while new candidate genes were sought using rare variant collapsing analysis and identification of novel loss-of-function variants in genes intolerant to such variation. Finally, 2 SCAD polygenic risk scores were applied to assess the contribution of common variants.

RESULTS

We identified 10 cases with at least one rare, likely disease-causing variant in CTD-associated genes, although only one had a CTD phenotype. No genes were significantly associated with SCAD from genome-wide collapsing analysis, however, enrichment for TGF (transforming growth factor)-β signaling pathway genes was found with analysis of 24 genes harboring novel loss-of-function variants. Both polygenic risk scores demonstrated that sporadic SCAD cases have a significantly elevated genetic SCAD risk compared with controls.

CONCLUSIONS

SCAD shares some genetic overlap with CTD, even in the absence of any major CTD phenotype. Consistent with a complex genetic architecture, SCAD patients also have a higher burden of common variants than controls.