Vascular histopathology and connective tissue ultrastructure in spontaneous coronary artery dissection: pathophysiological and clinical implications

From Atherosclerosis to Spontaneous Coronary Artery Dissection: Defining a Clinical and Genetic Risk Spectrum for Myocardial Infarction

PURPOSE OF REVIEW

Spontaneous coronary artery dissection (SCAD) has been increasingly recognized as a significant cause of acute myocardial infarction (AMI) in young and middle-aged women and arises through mechanisms independent of atherosclerosis. SCAD has a multifactorial etiology that includes environmental, individual, and genetic factors distinct from those typically associated with coronary artery disease. Here, we summarize the current understanding of the genetic factors contributing to the development of SCAD and highlight those factors which differentiate SCAD from atherosclerotic coronary artery disease.

RECENT FINDINGS

Recent studies have revealed several associated variants with varying effect sizes for SCAD, giving rise to a complex genetic architecture. Associated genes highlight an important role for arterial cells and their extracellular matrix in the pathogenesis of SCAD, as well as notable genetic overlap between SCAD and other systemic arteriopathies such as fibromuscular dysplasia and vascular connective tissue diseases. Further investigation of individual variants (including in the associated gene PHACTR1) along with polygenic score analysis have demonstrated an inverse genetic relationship between SCAD and atherosclerosis as distinct causes of AMI. SCAD represents an increasingly recognized cause of AMI with opposing clinical and genetic risk factors from that of AMI due to atherosclerosis, and it is often associated with complex underlying genetic conditions. Genetic study of SCAD on a larger scale and with more diverse cohorts will not only further our evolving understanding of a newly defined genetic spectrum for AMI, but it will also inform the clinical utility of integrating genetic testing in AMI prevention and management moving forward.

Spontaneous coronary artery dissection (SCAD): A contemporary review

Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of myocardial infarction that most frequently affects younger women, making it an important cause of morbidity and mortality within these demographics. The evolution of intracoronary imaging, improved diagnosis with coronary angiography, and ongoing research efforts and attention via social media, has led to increasing recognition of this previously underdiagnosed condition. In this review, we provide a summary of the current body of knowledge, as well as focused updates on the pathogenesis of SCAD, insights on genetic susceptibility, contemporary diagnostic tools, and immediate, short- and long-term management.

Angiographic patterns in spontaneous coronary artery dissection: novel diagnostic insights

INTRODUCTION

Spontaneous coronary artery dissection (SCAD) is a rare but well-recognized cause of acute coronary syndrome, especially important in women. Invasive coronary angiography (ICA) is the fundamental diagnostic technique for the confirmation of SCAD. Knowing the angiographic patterns suggestive of SCAD is essential for the correct identification of patients with this entity.

AREAS COVERED

In this narrative review, the main angiographic characteristics of SCAD lesions as detected by ICA are presented and discussed.

EXPERT OPINION

In addition to the specific angiographic classification of SCAD, several authors have described complementary angiographic patterns suggestive of SCAD. Knowledge and correct identification of these angiographic patterns is essential for the correct diagnosis of patients with clinical suspicion of SCAD.

Spontaneous Coronary Artery Dissection Resulting in Acute Myocardial Infarction With Cardiac Rupture

Spontaneous coronary artery dissection occurs predominantly in women and is associated with fibromuscular dysplasia. We illustrate a rare case of sudden coronary death as a result of cardiac rupture from spontaneous coronary artery dissection in a 54-year-old man without fibromuscular dysplasia. Cardiac rupture has been previously reported in 6 cases, mostly in women.

Exosome-specific loading Sox10 for the treatment of Cuprizone-induced demyelinating model

Demyelination is a pathological feature commonly observed in various central nervous system diseases. It is characterized by the aggregation of oligodendrocyte progenitor cells (OPCs) in the lesion area, which face difficulties in differentiating into mature oligodendrocytes (OLGs). The differentiation of OPCs requires the presence of Sox10, but its expression decreases under pathological conditions. Therefore, we propose a therapeutic strategy to regulate OPCs differentiation and achieve myelin repair by endogenously loading Sox10 into exosomes. To accomplish this, we generated a lentivirus-armed Sox10 that could anchor to the inner surface of the exosome membrane. We then infected HEK293 cells to obtain exosomes with high expression of Sox10 (exosomes-Sox10, ExoSs). In vitro, experiments confirmed that both Exos and ExoSs can be uptaken by OPCs, but only ExoSs exhibit a pro-differentiation effect on OPCs. In vivo, we administered PBS, Exos, and ExoSs to cuprizone-induced demyelinating mice. The results demonstrated that ExoSs can regulate the differentiation of PDGFRα+ OPCs into APC+ OLGs and reduce myelin damage in the corpus callosum region of the mouse brain compared to other groups. Further testing suggests that Sox10 may have a reparative effect on the myelin sheath by enhancing the expression of MBP, possibly facilitated by the exosome delivery of the protein into the lesion. This endogenously loaded technology holds promise as a strategy for protein-based drugs in the treatment of demyelinating diseases.

Spontaneous Coronary Artery Dissection in Clinical Practice: Pathophysiology and Therapeutic Approaches

Spontaneous coronary artery dissection (SCAD) is a cause of myocardial infarction without obstructive coronary artery disease (MINOCA). It is determined by a coronary artery wall layers separation, which occurs regardless of traumatic or iatrogenic injuries. Even if it is often a missed diagnosis, its incidence is growing along with the improvement of intracoronary imaging techniques that allow for better detection. The main angiographical classification distinguishes three different forms, with slightly different prognoses at long-term follow up. SCAD is a recurrent condition, severely hampering the life quality of affected patients. The predominantly young age of patients with SCAD and the high prevalence of females among them have made the topic increasingly important, especially regarding therapeutic strategies. According to the data, the most recommended treatment is conservative, based on the use of antiplatelet agents and supportive anti-ischemic therapy. However, there are conflicting opinions concerning the need for dual antiplatelet therapy and its duration. In the case of invasive treatment, the choice between percutaneous coronary intervention and coronary artery bypass graft depends on the patient's clinical stability and the interested vessel. The purpose of the current review is to revise the pathophysiological mechanisms underlying SCAD and the current knowledge of its treatment.

Prevalence and outcomes of select rare vascular conditions in females: A descriptive review

Rare vascular conditions frequently pose a diagnostic and therapeutic dilemma for health care providers. Several of these conditions have distinct relevance to females populations but, due to their infrequency, there has been little reported on the outcomes of rare vascular conditions specifically in females populations. We performed a literature review of a selection of three rare vascular conditions known to either disproportionately affect females (median arcuate ligament syndrome and fibromuscular dysplasia) or have unique manifestations in females populations (vascular Ehlers-Danlos syndrome). We performed a descriptive review of the literature focused on these three vascular conditions and identified aspects of the current available research describing sex-based differences in prevalence, any pathophysiology explaining the observed sex-based differences, and the contribution of sex to outcomes for each disease process. In addition, considerations for pregnant females with respect to each rare vascular disease process are discussed.

MINOCA biomarkers: Non-atherosclerotic aspects

Myocardial infarction in the absence of obstructive coronary artery disease (MINOCA) is an important subtype of myocardial infarction. Although comprising less than 50% stenosis in the main epicardial coronary arteries, it constitutes a severe health risk. A variety of approaches have been recommended, but definitive diagnosis remains elusive. In addition, the lack of a comprehensive understanding of underlying pathophysiology makes clinical management difficult and unpredictable. This review highlights ongoing efforts to identify relevant biomarkers in MINOCA to improve diagnosis, individualize treatment and better predict outcomes.

Pathophysiology of spontaneous coronary artery dissection: hematoma, not thrombus

Spontaneous coronary artery dissection (SCAD) accounts for 1.7%-4% of all acute coronary syndrome presentations, particularly among young women with an emerging awareness of its importance. The demarcation of acute SCAD from coronary atherothrombosis and the proper therapeutic approach still represents a major clinical challenge. Certain arteriopathies and triggers are related to SCAD, with high variability in their prevalence, and often, the cause remains unknown. The objective of this review is to provide contemporary knowledge of the pathophysiology of SCAD and possible therapeutic solutions.

From Fibromuscular Dysplasia to Arterial Dissection and Back

Fibromuscular dysplasia (FMD) is an idiopathic and systemic non-inflammatory and non-atherosclerotic arterial disease. Fifteen to 25% of patients with FMD present with arterial dissection in at least one arterial bed. Conversely, a substantial number of patients with renal, carotid, and visceral dissection have underlying FMD. Also, while few patients with FMD develop coronary artery dissection, lesions suggestive of multifocal FMD have been reported in 30-80% of patients with spontaneous coronary artery dissection (SCAD), and the relation between these two entities remains controversial. The frequent association of FMD with arterial dissection, both in coronary and extra-coronary arteries raises a number of practical and theoretical questions: (i) Are FMD and arterial dissections two different facets of the same disease or distinct though related entities? (ii) Is SCAD just a manifestation of coronary FMD or a different disease? (iii) What is the risk and which are predictive factors of developing arterial dissection in a patient with FMD? (iv) What proportion of patients who experienced an arterial dissection have underlying FMD, and does this finding influence the risk of subsequent arterial complications? In this review we will address these different questions using fragmentary, mostly cross-sectional evidence derived from large registries and studies from Europe and the United States, as well as arguments derived from demographics, clinical presentation, imaging, and when available histology and genetics. From there we will derive practical consequences for nosology, screening and follow-up.

Pericoronary adipose tissue density is increased in patients with recent spontaneous coronary dissection

OBJECTIVE

Inflammatory activity is one of the potential mechanisms of spontaneous coronary artery dissection (SCAD). Recently, the pericoronary adipose tissue attenuation (PCAT) derived from CT angiography (CTA) has been established as a method for measuring vascular inflammation. We aimed to characterise the pancoronary and vessel-specific PCAT in patients with and without recent SCAD.

METHODS

The study comprised patients with SCAD referred to a tertiary centre between 2017 and 2022 who underwent CTA and were compared with individuals with no prior SCAD. PCAT was analysed on end-diastolic CTA reconstructions along proximal 40 mm of all major coronary vessels as well as the SCAD-related vessel. We analysed 48 patients with recent SCAD (median 6.1 (IQR 3.5-14.9) months since SCAD, 95.8% female) and 48 patients in the group without SCAD.

RESULTS

Pancoronary PCAT was higher in patients with SCAD compared with those without SCAD (-80.6±7.9 vs -85.3 HU±6.1, p=0.002). Vessel-specific PCAT in patients with SCAD compared with patients without SCAD was higher for both the RCA (-80.9±9.5 vs -87.1±6.9 HU, p=0.001) and the LCA (-80.3±7.8 vs -83.4±7.2 HU, p=0.04). In patients with SCAD, PCAT of the SCAD-related vessel was not significantly different from averaged PCAT of unaffected vessels (-81.2±9.2 vs -80.6±7.6, p=0.74). There was no association between PCAT and the interval from SCAD to CTA.

CONCLUSIONS

Patients with recent SCAD have higher PCAT compared with patients without SCAD, suggesting an increased perivascular inflammatory activity. This association is not restricted to the dissected vessel.

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.

Histological evidence of a connection between true and false lumen in spontaneous coronary artery dissection

The pathophysiological mechanism underlying spontaneous coronary artery dissection remains unclear. Although an endothelial-intimal disruption is assumed to be involved as either a primary or secondary event, the presence of a tear in the coronary intima has not been histologically presented, to our knowledge. We present three autopsy cases of spontaneous coronary artery dissection in which histopathological examination revealed an intimal tear and connection between true and false lumen in the area of the dissection.

TyG index as a predictor of spontaneous coronary artery dissection in young women

OBJECTIVE

Spontaneous coronary artery dissection (SCAD) is a rare but potentially life-threatening pathology and cases are especially seen in women under 50 years of age and with relatively fewer cardiovascular risk factors. Although risk factors facilitating the development of SCAD have been defined in the literature, modifiable risk factors remain unclear. In this study, it was aimed to investigate the relationship between the triglyceride glucose index (TyG) and the development of SCAD in the population of young women.

METHODS

The results of 281 patients were analyzed and compared with each other in terms of clinical, demographic, laboratory parameters, and coronary angiography results.

RESULTS

The mean age was 45 years and all of them were female. When the groups were compared, the TyG and inflammatory parameters were higher in the SCAD group (p < 0.001). When these two groups with low cardiovascular risk factors were compared in logistic regression analysis, high TyG was found to be an independent predictor of SCAD development in young women (p < 0.001).

CONCLUSION

As a result, our study shows that the development of these non-atherosclerotic conditions can be predicted by simple biochemical tests in young women with low atherosclerotic cardiovascular risk factors.

Genome-wide association meta-analysis of spontaneous coronary artery dissection identifies risk variants and genes related to artery integrity and tissue-mediated coagulation

Spontaneous coronary artery dissection (SCAD) is an understudied cause of myocardial infarction primarily affecting women. It is not known to what extent SCAD is genetically distinct from other cardiovascular diseases, including atherosclerotic coronary artery disease (CAD). Here we present a genome-wide association meta-analysis (1,917 cases and 9,292 controls) identifying 16 risk loci for SCAD. Integrative functional annotations prioritized genes that are likely to be regulated in vascular smooth muscle cells and artery fibroblasts and implicated in extracellular matrix biology. One locus containing the tissue factor gene F3, which is involved in blood coagulation cascade initiation, appears to be specific for SCAD risk. Several associated variants have diametrically opposite associations with CAD, suggesting that shared biological processes contribute to both diseases, but through different mechanisms. We also infer a causal role for high blood pressure in SCAD. Our findings provide novel pathophysiological insights involving arterial integrity and tissue-mediated coagulation in SCAD and set the stage for future specific therapeutics and preventions.

Spontaneous coronary artery dissection: the emerging role of coronary computed tomography

Spontaneous coronary artery dissection (SCAD) is a cause of acute coronary syndrome and myocardial infarction, more frequent among young women. Invasive coronary angiography (ICA) is the gold standard for the diagnosis of SCAD, although the risk of propagating dissection flap is considerable. Therefore, coronary computed tomography angiography (CCTA) is an emerging alternative modality to diagnose SCAD with the advantage of being a non-invasive technique. Clinicians should be aware of the predisposing conditions and pathophysiology to raise the pre-test probability of SCAD and select the most appropriate diagnostic tools. In recent times, improvements in spatial and temporal resolution and the use of semi-automated software providing quantitative assessment make CCTA a valid alternative to ICA also for the follow-up. Moreover, CCTA may be helpful to screen and evaluate extra-coronary arteriopathies closely related to SCAD. In this review, we illustrate the current and the potential role of CCTA in the diagnosis of SCAD, highlighting advantages and disadvantages of this imaging modality compared to ICA.

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.

Spontaneous coronary artery dissection and exogenous estrogen in a transgender female

We report the case of a 37-year-old transgender patient with a history of orchiectomy on gender-affirming estrogen therapy who was hospitalized with an acute onset of chest pain with a resolution shortly after the presentation. On presentation, the patient had a rapid rise in troponin level and was urgently taken to the cardiac catheterization lab where spontaneous coronary artery dissection was diagnosed and treated with cutting balloon angioplasty and medical management. After a multidisciplinary discussion, the only notable risk factor was estrogen supplementation after gender reassignment surgery. To our knowledge, this is the only report of a male to female transgender patient reported to have spontaneous coronary artery dissection.

Optical Coherence Tomography and Coronary Dissection: Precious Tool or Useless Surplus?

Spontaneous coronary artery dissection (SCAD) is a rare clinical condition, but frequently manifested as acute myocardial infarction. In this particular setting, in recent years, optical coherence tomography (OCT) has been established as a possible diagnostic method due to the high spatial resolution (10–20 μm), which can visualize the different layers of coronary vessels. OCT can better analyze the “binary” or double lumen morphology, typical of this entity. Furthermore, it can identify the entrance breach and the circumferential and longitudinal extension of the lesion. However, we have to emphasize that this technique is not free from complications. OCT could further aggravate a dissection or exacerbate a new intimal tear. Therefore, the use of OCT in the evaluation of SCAD should be defined by balancing the diagnostic benefits versus procedural risks. Moreover, we underline that as SCAD is a rare condition and OCT is a recently introduced technique in clinical practice, limited data is available in literature.

The presence of thrombus in spontaneous coronary artery dissection: A systematic review of autopsy findings

Background

Spontaneous coronary artery dissection (SCAD) is an important cause of acute coronary syndrome in young women. There is no consensus on optimal treatment, though a conservative approach including antiplatelet agents is commonly used. We hypothesized that most cases of SCAD would not demonstrate true lumen thrombus in the dissected artery, suggesting that anti-platelet agents might not have a role in the treatment of SCAD.

Methods

We conducted a systematic review of the published literature through March 2022 to identify pathology images from individuals who died of SCAD. The images were independently reviewed by a pathologist to assess for the presence of thrombus and inflammatory cells.

Results

We identified 40 cases from 34 publications with available pathology images and found only one case of true lumen thrombus. Additionally, we found that 53% of cases involved eosinophilic inflammation.

Conclusion

The role of antiplatelet agents in the treatment of SCAD should be re-evaluated. Further studies are needed to better understand the significance and treatment implications of eosinophilic inflammation.

Prevalence and Disease Spectrum of Extracoronary Arterial Abnormalities in Spontaneous Coronary Artery Dissection

Question

What is the prevalence of fibromuscular dysplasia, aneurysms, dissection, and tortuosity in extracoronary arteries of patients who developed a spontaneous coronary artery dissection (SCAD)?

Findings

In this case series including 173 patients with SCAD, using magnetic resonance angiography with blinded interpretation of the findings, 32% of the patients had fibromuscular dysplasia, 8% had aneurysms, and 2% had dissections; the prevalence of arterial tortuosity was similar in cases and controls. Extracoronary vascular events over a median 5-year follow-up were rare.

Meaning

The findings of this blinded analysis suggest that, in patients with SCAD, severe multivessel fibromuscular dysplasia, aneurysms, and dissections are infrequent and seldom associated with clinically evident vascular events.

Importance

Spontaneous coronary artery dissection (SCAD) has been associated with fibromuscular dysplasia (FMD) and other extracoronary arterial abnormalities. However, the prevalence, severity, and clinical relevance of these abnormalities remain unclear.

Objective

To assess the prevalence and spectrum of FMD and other extracoronary arterial abnormalities in patients with SCAD vs controls.

Design, Setting, and Participants

This case series included 173 patients with angiographically confirmed SCAD enrolled between January 1, 2015, and December 31, 2019. Imaging of extracoronary arterial beds was performed by magnetic resonance angiography (MRA). Forty-one healthy individuals were recruited to serve as controls for blinded interpretation of MRA findings. Patients were recruited from the UK national SCAD registry, which enrolls throughout the UK by referral from the primary care physician or patient self-referral through an online portal. Participants attended the national SCAD referral center for assessment and MRA.

Exposures

Both patients with SCAD and healthy controls underwent head-to-pelvis MRA (median time between SCAD event and MRA, 1 [IQR, 1-3] year).

Main Outcome and Measures

The diagnosis of FMD, arterial dissections, and aneurysms was established according to the International FMD Consensus. Arterial tortuosity was assessed both qualitatively (presence or absence of an S curve) and quantitatively (number of curves ≥45%; tortuosity index).

Results

Of the 173 patients with SCAD, 167 were women (96.5%); mean (SD) age at diagnosis was 44.5 (7.9) years. The prevalence of FMD was 31.8% (55 patients); 16 patients (29.1% of patients with FMD) had involvement of multiple vascular beds. Thirteen patients (7.5%) had extracoronary aneurysms and 3 patients (1.7%) had dissections. The prevalence and degree of arterial tortuosity were similar in patients and controls. In 43 patients imaged with both computed tomographic angiography and MRA, the identification of clinically significant remote arteriopathies was similar. Over a median 5-year follow-up, there were 2 noncardiovascular-associated deaths and 35 recurrent myocardial infarctions, but there were no primary extracoronary vascular events.

Conclusions and Relevance

In this case series with blinded analysis of patients with SCAD, severe multivessel FMD, aneurysms, and dissections were infrequent. The findings of this study suggest that, although brain-to-pelvis imaging allows detection of remote arteriopathies that may require follow-up, extracoronary vascular events appear to be rare.

Recent Advances on the Genetics of Spontaneous Coronary Artery Dissection

Spontaneous coronary artery dissection (SCAD) has been acknowledged as a significant cause of acute myocardial infarction, predominantly in young to middle-aged women. SCAD often occurs in patients with fewer cardiovascular risk factors than atherosclerotic acute myocardial infarction. Unfortunately, SCAD remains underdiagnosed due to a lack of awareness among health care providers leading to misdiagnosis. The underlying pathophysiological mechanisms of SCAD are not well understood. SCAD occurring in members of the same family has been described, suggesting a potentially identifiable genetically triggered cause in at least some cases. However, thus far, the search for highly penetrant mutations in candidate pathways has had a low yield, often pointing to genes involved in other clinically undiagnosed hereditary syndromes manifesting as SCAD. Recent exploratory efforts using exome sequencing and genome-wide association studies have provided several interesting leads toward understanding the pathogenesis of SCAD. Here, we review recent publications where rare and common genetic factors were reported to associate with a predisposition to SCAD and indicate suggestions for the future strategies and approaches needed to fully address the genetic basis of this intriguing and atypical cause of acute myocardial infarction.

Spontaneous Coronary Artery Dissection: Pitfalls of Angiographic Diagnosis and an Approach to Ambiguous Cases

Spontaneous coronary artery dissection (SCAD) is a pathophysiologically distinct cause of acute coronary syndromes (ACS). It is increasingly recognized that optimal management is different from that for atherosclerotic ACS and that a SCAD diagnosis has specific long-term prognostic and therapeutic implications. Accurate diagnosis is therefore essential to ensure the best treatment of patients. At present this relies on the recognition of typical features of SCAD identified on invasive coronary angiography. Although most SCAD can be readily distinguished angiographically from alternative causes of ACS, false positive and false negative diagnoses remain common. In particular, sometimes non-SCAD presentations, including atherothrombosis, takotsubo cardiomyopathy, coronary embolism, coronary vasospasm, contrast streaming, and myocardial infarction with nonobstructive coronary arteries, can mimic angiographic features usually associated with SCAD. The authors present the combined experience from European and US SCAD referral centers reviewing the classical angiographic appearances of SCAD, presenting potential diagnostic pitfalls and exemplars of SCAD mimickers. The authors further review the benefits and limitations of intracoronary imaging in the context of SCAD. Finally, the authors discuss the investigation of ambiguous cases and an approach to minimize misdiagnosis in difficult cases.