Spontaneous Coronary Artery Dissection: Time for Development of a Large National Registry

Spontaneous coronary artery dissection (SCAD) is a challenging clinical condition because of the heterogeneous nature of its presentation. The first case report of SCAD was published in 1931 of a 42-year-old woman who died suddenly after vomiting and retching and was later found to a have ruptured right coronary artery atheroma.¹ Since then, several case reports and small retrospective case series with limited follow-up were published.^2-6 Our knowledge regarding this clinical entity is so limited that actual prevalence of the disease is unknown. It was thought to be a rare disorder, with estimated prevalence ranging from 0.1%-0.28% among patients presenting with acute coronary syndromes.² However, this could have been underestimated, and in the era of using advanced imaging modalities, such as intravascular ultrasound (IVUS) and optical coherence tomography (OCT), recent reports have estimated the prevalence to be as high as 4%.³ Although there is no standard reporting mechanism for cases of SCAD, the awareness of the disease may be better recognized now, leading to an apparent increase in incidence.

In this issue of the Journal of Invasive Cardiology, Sultan and Kreutz present a retrospective case series of 10 patients with SCAD.⁵ The clinical heterogeneity of SCAD in terms of the initial presentation and subsequent clinical course is clearly evident in this small case series. While most patients presented with ST-segment elevation myocardial infarction (STEMI), there was 1 patient who presented with cardiac arrest and 1 patient with non-STEMI. The clinical course also ranged from spontaneous resolution with conservative management to those requiring revascularization with percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) surgery. One patient died from refractory cardiogenic shock despite revascularization. One-half of the conservatively managed patients had recurrence of symptoms and worsening of dissection during the same hospitalization. The variables involved in risk stratification to identify those patients who might clinically deteriorate vs those who remain stable on conservative management are still unknown, making the management of SCAD very difficult. Revascularization in these patients with either PCI or CABG is also associated with a unique set of technical challenges. Identification of the true lumen during guidewire insertion, need for placement of multiple overlapping stents increasing the predisposition to stent malapposition, fracture and subsequent thrombosis pose problems during PCI.⁵ Lack of structural integrity of target vessel and poor coronary run-off do not make CABG an excellent option for revascularization either.⁵ 

Like most rare clinical conditions, our understanding of SCAD is based on sporadic case reports and case series. To date, there are no data from multicenter trials to guide treatment of patients with SCAD. This is a major limitation, as basing clinical decisions solely on case reports or small retrospective studies is inherently flawed. Our poor understanding of the natural history of the disease due to publication bias and lack of organized, long-term follow-up outcome studies have prevented the formation of clinical treatment guidelines. For example, SCAD was initially thought to be a disease predominantly affecting young women. However, in a recently published, large, prospective study from Vancouver General Hospital in Canada involving 168 patients with non-atherosclerotic SCAD, the average age of presentation was 52.1 years and 62% of all patients were postmenopausal.⁴ Also, unlike previous reports of SCAD being idiopathic, association with arteriopathies such as fibromuscular dysplasia was noted in this study.⁴ The most common angiographic appearance was a long, smooth stenosis rather than the stereotypical arterial wall stain that was previously described.⁴ The largest series of SCAD patients reported to date is from the Mayo Clinic, involving 246 patients.⁶ In this study, coronary artery tortuosity was found to be highly prevalent in patients with SCAD.⁶ Also, the tortuosity was found to be associated with recurrent SCAD events with recurrence most commonly within the tortuous segments.⁶ The novel findings from both these studies illustrate that knowledge based on anecdotal case reports and small case series is extremely limited and can sometimes even be erroneous. 

Due to the paucity of clinical data, all aspects of SCAD, including incidence, prevalence, underlying etiology, recurrence rates, long-term prognosis, and management, remain unknown and ambiguous. Hence, large, multicenter, prospective studies are of paramount importance to provide novel insights into the pathophysiology and treatment of SCAD. The development of registries for SCAD began only recently. DISCOVERY (Dissection of Coronary Arteries, Venetto and Emilia Registry) is a multicenter SCAD registry formed in 2009 and involving 22 cardiovascular centers in Italy, with the goal of enrolling at least 40 SCAD patients per year.⁷ The outcomes from this registry are yet to be published. The Canadian SCAD study (NCT02188069) was recently launched, aiming to prospectively enroll up to 1000 patients with SCAD throughout Canada to evaluate the natural history of the disease. In the United States, the Mayo Clinic is in the process of developing a virtual multicenter SCAD registry (NCTO1429727). A disease-specific social media networking system is being used to recruit patients into this registry.⁸ Despite these efforts, the Mayo registry will still not be nationally based, and will miss the majority of SCAD patients who are not referred to Mayo Clinic and are not using the disease-specific social networking sites. 

The development of a large, comprehensive, sustainable national registry for this relatively rare disorder requires a significant amount of time, resources, and effort. It is best achieved by a concentrated and collaborative effort across multiple cardiovascular societies such as the American College of Cardiology, American Heart Association, and Society for Cardiac Angiography and Intervention, rather than by a single institution, so as to be inclusive and capture the majority of cases in the country. Consistent collection of longitudinal data in these registries will also facilitate creation of a standard care set to help in the management of these patients. We should build upon the existing cardiovascular data repository, the National Cardiovascular Data Registry (NCDR), and extend the cath PCI form to include collection of specific variables related to SCAD. 

In summary, SCAD is a complex and uniquely unusual, yet life-threatening, cardiovascular disease typically affecting young patients. As our technology advances, the ability to detect and diagnose SCAD may substantially improve, which may anecdotally appear as an increased incidence of the disease. Given the heterogeneity of the clinical presentation of SCAD and lack of organized data collection, our clinical understanding of this disease remains limited. We still have a long way to go in understanding the etiology and risk factors of the disease and subsequently in streamlining its management. We believe a concentrated research effort to develop a large-scale, national, multicenter SCAD registry is in order, which will provide a data repository from which we can hopefully improve our understanding of this disease and identify the best prevention and treatment options.

References

1. Pretty H. Dissecting aneurysms of coronary artery in woman aged 42: rupture. BMJ. 1931;1:667.
2. Vanzetto G, Berger-Coz E, Barone-Rochette G, et al. Prevalence, therapeutic management and medium-term prognosis of spontaneous coronary artery dissection: results from a database of 11,605 patients. Eur J Cardiothorac Surg. 2009;35(2):250-254. Epub 2008 Nov 28.
3. Nishiguchi T, Tanaka A, Ozaki Y, et al. Prevalence of spontaneous coronary artery dissection in patients with acute coronary syndrome. Eur Heart J Acute Cardiovasc Care. 2013 Sept 11 (Epub ahead of print). 
4. Saw J, Aymong E, Sedlak T, et al. Spontaneous coronary artery dissection: association with predisposing arteriopathies and precipitating stressors, and cardiovascular outcomes. Circ Cardiovasc Interv. 2014;7(5):645-655. Epub 2014 Oct 7.
5. Sultan A, Kreutz RP. Variations in clinical presentation, risk factors, treatment, and prognosis of spontaneous coronary artery dissection. J Invasive Cardiol. 2015:27(8):363-369.
6. Eleid MF, Guddeti RR, Tweet MS, et al. Coronary artery tortuosity in spontaneous coronary artery dissection: angiographic characteristics and clinical implications. Circ Cardiovasc Interv. 2014;7(5):656-662. Epub 2014 Aug 19.
7. Fontanelli A, Olivari Z, La Vecchia L, et al. Spontaneous dissections of coronary arteries and acute coronary syndromes: rationale and design of the DISCOVERY, a multicenter prospective registry with a case-control group. J Cardiovasc Med (Hagerstown). 2009;10(1):94-99.
8. Tweet MS, Gulati R, Aase LA, Hayes SN. Spontaneous coronary artery dissection: a disease-specific, social networking community-initiated study. Mayo Clin Proc. 2011;86(9):845-850.

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From the Division of Cardiology, Baystate Medical Center, Springfield, Massachusetts.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Address for correspondence: Gregory R. Giugliano, Division of Cardiology, Baystate Medical Center, Springfield, MA 01199. Email: Gregory.giugliano@bhs.org