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Case Media

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Episode Schematics & Teaching – SCAD

Pearls – SCAD

Notes – SCAD

1. What is SCAD and how does it present?

• Spontaneous coronary artery dissection (SCAD) is defined as an epicardial coronary dissection that is not associated with atherosclerosis or instrumentation.
• This occurs with hematoma formation within the tunica media,  thereby potentially compressing the arterial true lumen leading to ischemia.
• There are two proposed mechanisms of hematoma formation: “inside-out” and “outside-in”. The inside-out hypothesis posits that the hematoma arises from the true lumen via a dissection flap – an endothelial-intimal disruption. Conversely the outside-in hypothesis posits that the hematoma arises de novo within the media through disruption of traversing microvessels.
• There is a wide range of clinical presentation for SCAD varying in severity including asymptomatic / benign presentation, anginal syndromes, acute myocardial infarction, VT/VF arrest, and cardiogenic shock. Our patient presented with VF arrest and ACS.
• SCAD epidemiology is confounded by a lack of awareness. A high index of suspicion is warranted. Diagnosis can be missed in young or mid-life without CV risk factors who would present with atypical/mild chest pain.

2. What are the etiologies of SCAD?

• SCAD is associated with the peripartum state (presumed due to combination of hormonal mediated vessel wall integrity changes and hemodynamic stressors), illicit substance use, autoimmune disorders, connective tissue disorders, fibromuscular dysplasia, and vigorous external stressors.
• Many patients recall extreme physical or emotional stress preceding the event. Men are more likely to present in the setting of a physical stressor whereas women are more likely to report an emotional stressor.
• Pregnancy-associated SCAD is most common in the first week after delivery like our patient.
• Genetic evaluation for connective tissue disorders and aortopathy syndromes (i.e., Marfan, Loeys-Dietz, and Ehlers-Danlos) should be considered.
• Arterial imaging to identify significant extracoronary vascular abnormalities is recommended since there is the association of SCAD with fibromuscular dysplasia.

3. What is the gold standard to diagnose SCAD?

• Coronary angiography performed by an experienced interventional cardiologist is the gold standard to diagnose SCAD. The left anterior descending artery is most commonly affected, and most cases of SCAD occur in the mid-distal arteries.
• There are 3 angiographic variants SCAD.
  • Type 1 is with evident with the contrast dye staining the arterial wall with multiple radiolucent lumen.
  • Type 2 (majority of the cases including the present case) is diffuse stenosis of varying severity with subtle abrupt changes in arterial caliber (long smooth narrowing).
  • Type 3 mimics atherosclerosis and is often difficult to differentiate from it.

4. What is the management of SCAD in acute setting?

• Management of SCAD depends on clinical severity. Thrombolytics should be avoided. Most cases are benign and treated conservatively with work up for secondary causes. 95% of conservatively treated patients with mild SCAD such as minimal ongoing ischemia with preserve coronary flow will heal within 30 days. More severe cases of SCAD require intervention such as PCI or CABG. Surgical approaches are preferred in left main involvement, long segments, and with diffuse coronary artery involvement like in our case. Utilizing vein grafts is preferred as most SCAD cases heal with eventual graft closure. Off note, PCI in SCAD is associated with higher complication rates and suboptimal outcomes, including risk of iatrogenic dissection or propagation of hematoma.

5. What is the management of SCAD in pregnant patient?

• The management strategy of SCAD during pregnancy is similar to that in the nonpregnant state, with additional considerations to optimize maternal and fetal outcomes. After 20 weeks gestation, recommend left lateral recumbent positioning whenever possible to reduce aortocaval compression and optimize venous return. If necessary, consider maternal stabilization and optimization of cardiac status followed by planned delivery under controlled conditions. For more, enjoy Episode #167 – Cardiac Interventions During Pregnancy with Dr. Michael Luna.

5. What is the prognosis of SCAD and long-term management?  

• Recurrent SCAD has been reported in 10-30% of patients. Post-SCAD chest pain is common and may persist for many months. Due to iatrogenic risk from invasive angiography, serial electrocardiography and biomarker assessment, and noninvasive cardiac computed tomography angiography should be considered. Standard heart failure medications are indicated for left ventricular dysfunction, and hypertension should be treated.

6. How to prevent recurrent SCAD?

• The factors associated with recurrence remain poorly understood. After SCAD, further pregnancy should perhaps be discouraged and contraception should be discussed. Women who strongly desire pregnancy should receive thorough preconception counseling.

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References

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