Spontaneous Coronary Artery Dissection (SCAD)

Summary

Key Terms

SCAD

Spontaneous Coronary Artery Dissection. epicardial coronary artery dissection that is not associated with atherosclerosis or trauma and not iatrogenic.

IMH

Intramural hematoma

FMD

Fibromuscular Dysplasia

Epidemiology

• Risk Factors
  • female sex w/ average age 45-53
  • Pregnancy
  • physical and emotional stress triggers
  • concurrent systemic arteriopathies
  • fibromuscular dysplasia
• Prevalence
  • The true prevalence of SCAD remains uncertain, primarily because it is an underdiagnosed condition. Missed diagnoses are driven by a low suspicion of ACS in young women even in the presence of classic presenting symptoms, limitations of current coronary angiographic techniques, and lack of clinician familiarity with the condition. SCAD most commonly occurs in patients with few or no traditional cardiovascular risk factors^1-AHA
  • In pregnancy, 1.81 SCAD events per 100 000 pregnancies during pregnancy or in the 6-week postpartum period
• Complications
  • Most common cause of pregnancy associated MI (43%)^1-AHA
• Mortality

Etiology

• Most Common Cause of pregnancy associated myocardial infarction (MI) (43%)

Artery	Frequency of Cases
Left Anterior Descending Artery	32%–46%
Left Anterior Descending, Diagonal, and Septal Branches	45%–61%
Circumflex, Ramus, and Obtuse Marginal Branches	15%–45%
Right Coronary Artery, Acute Marginal, Posterior Descending, and Posterolateral Branches	10%–39%
Left Main Artery	Up to 4%

Pathophysiology

• Spontaneous formation of IMH within the wall of a coronary artery. This leads to intimal disruption rather than atherosclerotic plaque rupture or intraluminal thrombus.
• Separation occurring in the outer third of the tunica media and IMH occupying the dissection and compressing the true lumen, leading to coronary insufficiency and MI
• Dissection lengths are often extensive that can occur as spiral, retrograde dissection into proximal artery

HPI

• wide range based on severity from asymtomatic, chest pain, to vfib cardiac arrest, or sudden death.
• Chest pain most common

Physical Exam

• correlates with level os severity of SCAD
• Often unremarkable in stable patients
• Signs of acute coronary syndrome (e.g., diaphoresis, pallor, tachycardia)
• Chest pain with or without radiation
• Hypotension or signs of cardiogenic shock in severe cases
• Possible signs of heart failure (e.g., jugular venous distension, pulmonary crackles) if left ventricular dysfunction is present

Diagnostics

• Gold Standard:Optical Coherence Tomography
• EKG: both STEMI and NSTEMI presentations
• Troponin:Often elevated
• EchoLV dysfunction correlating with affected coronary artery
• Coronary Angiography
  • Use femoral access because 3 fold risk of catheter induced iatrogenic dissection vs radial access
  • go to test d/t wide availabliity.
  • Perform especially in setting of STEMI. Limiting factor is the test is 2 dimentional and does not specifically image arterial wall. Must perform before intracoronary imaging to ensure no futher damage to coronary occurs
• Intravascular Ultrasonography
• Optical Coherence Tomography intracoronary method that uses light waves to image arterial wall. Gold standard for diagnosing SCAD but very few centers have this technology. Perform regular coronary angiography prior to ensure no further damage will occur to coronary by imaging.

Saw Angiographic SCAD Classification

Type	Description
Type 1	Intimal tear with contrast dye staining the arterial wall and creating a false lumen.
Type 2	Diffuse narrowing of the artery due to intramural hematoma without an intimal tear.
Type 3	Focal narrowing that mimics atherosclerosis, requiring advanced imaging for diagnosis.

Treatment

Very limited amount of evidence to guide therapy choice most due to recent recognition of SCAD as important clinical entity. Most evidence is expert opinion from members of the AHA writing group on SCAD.

• Conservative Therapy
  • Prefered, if pt stable, given the risks of further injury with PCI and graft failure d/t competiive flow after coronary healing after CABG.
• PCI
  • consistently associated with suboptimal outcomes. Coronary guidewire may enter false lumen, ballooning/stent placement may worsen dissection,
• DAPT
  • If successful PCI then place pt on dual antiplatelet therapy.
• CABG
  • competitive flow often d/t native SCAD vessel healing
• Mechanical Support Devices
  • Devices can be used to maintain perfussion to end organs to allow heart to rest or as a bridge therapy to myocardial recovery, revasculaiztion, or to transplant
  • Intraaortic Balloon Pump
  • ECMO

Referrals

Case Study

References

1. Hayes SN, Kim ESH, Saw J, et al. Spontaneous Coronary Artery Dissection: Current State of the Science: A Scientific Statement From the American Heart Association. Circulation. 2018;137(19):e523-e557. doi:10.1161/CIR.0000000000000564