Epidemiology: True incidence and prevalence is unknown and has been historically underestimated.
Incidence: It has been suggested that SCAD may be the cause up to 1 – 4% of ACS cases overall (Hayes 2018).
- It is most common among women typically lacking classic cardiac disease risk factors.
- Highest incidence is within the subgroup of women less than 50 years of age, ranging from 8.7% to 35% (Yang 2020, Vanzetto 2009, Saw 2014, Hayes 2018, Nakashima 2016).
- SCAD has also been identified as the most common cause of pregnancy-associated MI (Hayes 2018).
Age: Average age ranges from 45 to 53 years of age (Hayes 2018).
Gender: Clear female to male predominance is seen in SCAD.
Morbidity/Mortality: High rates of intermediate, long term, and 10-year major adverse cardiac events and recurrent MI (Hayes 2018).
Poor Prognostic Factors:
- Identification of poor prognostic factors or risk factors is difficult due to small sample sizes of studies (see overview graphic).
- Severe anatomical coronary tortuosity has been identified as the only risk factor for recurrence (Hayes 2018).
Pathogenesis: The true pathophysiology of SCAD is still being elucidated but two principle mechanisms have been proposed:
- Inside-Out Hypothesis:
- A coronary arterial wall tear in the endothelium-intima layer allows for the creation of a false lumen that compromises coronary blood flow (Jackson 2019).
- Outside-in Hypothesis:
- A primary event outside the intima leads to expanding intramural hemorrhage and creation of a false lumen that that compromised coronary blood flow (Jackson 2019).
- Two potential phenomena may manifest at this juncture:
- Rupture of the intima-media membrane creates fenestrations, allowing for pressure equalization between the true and false lumen (Jackson 2019).
- In the absence of fenestrations, the pressurized false lumen continues to compromise blood flow in the true lumen (Jackson 2019).
History and Physical:
- Fibromuscular Dysplasia (FMD): A non-inflammatory and non-atherosclerotic vascular disorder that affects arterial walls, manifesting as stenosis, aneurysms, tortuosity, or dissection (Hayes 2018).
- FMD is the most common extra-coronary vascular abnormality in patients with SCAD.
- Pregnancy: Pregnancy-associated SCAD is the most common cause of MI among pregnant and postpartum patients (Hayes 2018, Elkayam 2014).
- Majority of SCAD occurs in the third trimester or early post-partum period.
- Systemic Inflammatory Disorders: Case reports have attributed systemic inflammatory disorders, autoimmune, and rheumatologic disease with SCAD.
- These may not be a true association as case reports and small series did not control for the prevalence of these conditions in the general population.
- Inherited Arteriopathies and Connective Tissue Disorders: An infrequent cause of SCAD.
Precipitating Factors: Although not present in all patients with SCAD, there appears to be a link between certain potential triggers and precipitants that may initiate spontaneous intimal tears or mediate intramural hematoma formation (Hayes 2018).
- Extreme Physical or Emotional Stress: The most commonly reported precipitants before the patient’s SCAD event.
- Intense Exercise
- Intense Emotional Stress
- Valsalva Activities
- Recreational Drugs (Cocaine, Amphetamines)
- Hormone-Mediated Triggers: These triggers have less supportive data, but associations have been reported in the literature (Hayes 2018).
- Oral Contraceptive Pills
- Postmenopausal Hormone Therapy
- Infertility Treatment
- High-Dose Corticosteroid Administration
Symptoms/Physical Examination: Patients present with symptoms and physical examination that are consistent with ACS and frequently exhibit increased levels of cardiac enzymes (Hayes 2018).
Diagnosis:
- Diagnosis is difficult and patients may be mistakenly discharged or have an incomplete work-up done due to their relatively young age and lack of risk factors for ACS.
- Accurate diagnosis in the acute stages of ACS is paramount as the management and investigation of SCAD is different from other causes of ACS (Hayes 2018).
- STEMI: Distribution of ST-Segment changes will correspond to dissecting coronary artery.
- LAD is the most commonly involved vessel in SCAD: Thus, look for convex ST-segment elevations in the anterior leads
- NSTEMI: Transient ST elevation, ST depression, new T wave inversions, or other EKG changes with elevations in cardiac enzymes.
Labs: Cardiac enzymes are frequently increased in patients with SCAD.
- Initial troponin level in patients with SCAD may be normal.
- Other labs are drawn to assist inpatient management and rule out other etiologies
- CBC, CMP, Coagulation Panel, HCG
- Autoimmune Workup, Inherited Arteriopathies and Connective Tissue Disorders Workup
Cardiac Diagnostics:
- Coronary Angiography: Once SCAD is suspected, angiography remains the first-line diagnostic modality.
- Most commonly involved vessels: Left Anterior Descending > Left Circumflex > Right Coronary Artery (Yang 2020).
- Three Angiographic Patterns of SCAD (Yang 2020):
- Type 1: Multiple visualized lumens within the arterial wall along with extraluminal contrast staining
- Type 2: Most commonly seen and can be missed on angiography. Arterial caliber is noted to have areas of long, diffuse narrowing
- Type 3: Visualization of focal or tubular stenosis of the involved artery
- Limitation:
- Does not image the arterial wall in great detail and carries a higher risk of catheter-induced coronary artery dissection in patients with SCAD due to underlying arterial fragility.
- Intracoronary Imaging: Provide detailed visualization and aids in diagnosis of SCAD but have additional risks, costs, and availability drawbacks.
- Optical Coherence Tomography (OCT): Allows for detailed coronary arterial wall visualization.
- Intravascular Ultrasound (IVUS): Excellent spatial resolution for coronary arterial wall visualization.
- Coronary Computed Tomography Angiography (CCTA):
- Role of CCTA in SCAD has not been adequately studied at this time.
- Not recommended as first-line for diagnosis of SCAD.
Management:
-
- Majority of patients have angiographic healing of SCAD lesions without intervention.
- Conservatively managed patients who have recurrent MI may require emergency revascularization.
- Medical Therapy:
- Dual-Antiplatelet Therapy (Hayes 2018, Amsterdam 2014):
- Patients with SCAD who undergo revascularization should receive dual-antiplatelet therapy
- Evidence for dual-antiplatelet therapy for SCAD patient who do not undergo coronary intervention is currently lacking.
- Expert opinion currently is to recommend dual-antiplatelet therapy for at least 1 year after occurrence of SCAD and lifelong aspirin.
- Beta-Blockers (Hayes 2018):
- Recommended in SCAD patients with evidence of HTN, arrhythmias, or LV dysfunction.
- Expert opinion advocates for use of beta-blockers after selecting out those at risk for adverse effects.
- Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers (Hayes 2018):
- Should be considered if LV systolic dysfunction is noted.
- Concern for teratogenicity in female patients of reproductive age.
- Anticoagulation (Hayes 2018, Yip 2015):
- If systemic anticoagulation is started at initial presentation, consideration for discontinuation is reasonable once SCAD is diagnosed based on expert opinion.
- Statins:
- Not routinely recommended after SCAD.
- SCAD patients with high-risk features:
- High-Risk Features (Yang 2020, Saw 2016):
- Left Main Coronary Artery Dissection
- Ongoing or Recurrent Ischemia or Chest Pain
- Ventricular Tachycardia or Ventricular Fibrillation
- Cardiogenic Shock
- High-Risk Features (Yang 2020, Saw 2016):
- Dual-Antiplatelet Therapy (Hayes 2018, Amsterdam 2014):
- Majority of patients have angiographic healing of SCAD lesions without intervention.
- Percutaneous Coronary Intervention (PCI) or Coronary Artery Bypass Grafting (CABG) should be considered (Hayes 2018).
- PCI: Due to coronary artery fragility observed in SCAD, PCI is associated with increased risk of complications and variables outcomes.
- CABG: Described for SCAD patients with left main or proximal dissection, those with failure of attempted PCI, and those with refractory ischemia despite conservative approach (Hayes 2018).
Guest Post By:
Muhammad Durrani, DO, MS
Assistant Clerkship Director, Assistant Research Director
Inspira Medical Center Emergency Department
Vineland, NJ
Twitter: @IbbyDurrani
References:
- Hayes S et al. Spontaneous Coronary Artery Dissection: Current State of the Science: A Scientific Statement From the American Heart Association. Circulation. 2018. PMID: 29472380
- Janssen E et al. Spontaneous coronary artery dissections and associated predisposing factors: a narrative review. Neth Heart J. 2019. PMID: 30684142
- Yang C et al. Spontaneous Coronary Artery Dissection: Latest Developments and New Frontiers. Curr Atheroscler Rep. 2020. PMID: 32734349
- Vanzetto 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. PMID: 19046896
- Saw J et al. Spontaneous coronary artery dissection: association with predisposing arteriopathies and precipitating stressors and cardiovascular outcomes. Circ Cardiovasc Interv. 2014. PMID: 25294399
- Saw J et al. Nonatherosclerotic coronary artery disease in young women. Can J Cardiol. 2014. PMID: 24726091
- Nakashima T et al. Prognostic impact of spontaneous coronary artery dissection in young female patients with acute myocardial infarction: A report from the Angina Pectoris-Myocardial Infarction Multicenter Investigators in Japan. Int J Cardiol. 2016. PMID: 26820364
- Jackson R et al. Spontaneous Coronary Artery Dissection: Pathophysiological Insights From Optical Coherence Tomography. JACC Cardiovasc Imaging. 2019. PMID: 30878439
- Saw J et al. Spontaneous coronary artery dissection: prevalence of predisposing conditions including fibromuscular dysplasia in a tertiary center cohort. JACC Cardiovasc Interv. 2013. PMID: 23266235
- Rogowski S et al. Spontaneous Coronary Artery Dissection: Angiographic Follow-Up and Long-Term Clinical Outcome in a Predominantly Medically Treated Population. Catheter Cardiovasc Interv. 2017. PMID: 26708825
- Prasad M, Tweet MS, Hayes SN, et al. Prevalence of extracoronary vascular abnormalities and fibromuscular dysplasia in patients with spontaneous coronary artery dissection. Am J Cardiol. 2015. PMID: 25929580
- Elkayam U et al. Pregnancy-associated acute myocardial infarction: a review of contemporary experience in 150 cases between 2006 and 2011. Circulation. 2014. PMID: 24753549
- Tweet M et al. Clinical features, management, and prognosis of spontaneous coronary artery dissection. Circulation. 2012. PMID: 22800851
- Lindor R et al. Emergency Department Presentation of Patients with Spontaneous Coronary Artery Dissection. J Emerg Med. 2017. PMID: 27727035
- Prakash R et al. Catheter-Induced Iatrogenic Coronary Artery Dissection in Patients With Spontaneous Coronary Artery Dissection. JACC Cardiovasc Interv. 2016. PMID: 27609262
- Awadalla H et al. Catheter-induced left main dissection incidence, predisposition and therapeutic strategies experience from two sides of the hemisphere. J Invasive Cardiol. 2005. PMID: 15831980
- Saw J et al. Contemporary Review on Spontaneous Coronary Artery Dissection. J Am Coll Cardiol. 2016. PMID: 27417009
- Tweet M et al. Spontaneous coronary artery dissection: revascularization versus conservative therapy. Circ Cardiovasc Interv. 2014. PMID: 25406203
- Lettieri C et al. Management and Long-Term Prognosis of Spontaneous Coronary Artery Dissection. Am J Cardiol. 2015. PMID: 25937347
- Yip A et al. Spontaneous coronary artery dissection-A review. Cardiovasc Diagn Ther. 2015. PMID: 25774346
- Amsterdam E et al. 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014. PMID: 25249586
Post Peer Reviewed By: Anand Swaminathan, MD (Twitter: @EMSwami) and Salim R. Rezaie, MD (Twitter: @srrezaie)
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