What is the management of acute coronary syndrome secondary to spontaneous dissection of a proximal coronary artery?

Management of Acute Coronary Syndrome Secondary to Spontaneous Coronary Artery Dissection

For acute coronary syndrome secondary to spontaneous coronary artery dissection (SCAD) of a proximal coronary artery, a conservative approach should be the preferred strategy unless the patient has ongoing ischemia, hemodynamic instability, or involves the left main or proximal two-vessel disease. 1

Definition and Epidemiology

Spontaneous coronary artery dissection (SCAD) is defined as a non-atherosclerotic, non-traumatic separation of the coronary arterial tunics due to vasa vasorum hemorrhage or intimal tear, creating a false lumen that compresses the true lumen and causes downstream myocardial ischemia 1. SCAD:

• Accounts for up to 4% of all ACS cases
• Has much higher prevalence (22-35%) in women <60 years old
• Is particularly common in pregnancy-related MI
• Is associated with fibromuscular dysplasia, anxiety, depression, and neuropsychiatric disorders 1

Diagnosis

Diagnosis of SCAD requires:

• Clinical presentation: Usually chest discomfort with elevated cardiac biomarkers 1
• Coronary angiography: The gold standard for diagnosis
• Consider adjunctive diagnostic strategies if uncertainty exists:
  • OCT/IVUS if feasible/safe
  • CT coronary angiography (especially for proximal lesions)
  • CT/MRA imaging for extracoronary vascular abnormalities, fibromuscular dysplasia
  • Repeat coronary angiography at 6-8 weeks 1

Management Algorithm

1. Initial Assessment: Determine Clinical Stability and Anatomy

• Clinically stable with non-high-risk anatomy:

  • Conservative medical therapy
  • Monitor as inpatient for 3-5 days 1

• Clinically stable with high-risk anatomy (left main or proximal 2-vessel dissection):

  • Consider CABG
  • Conservative therapy may be reasonable in select cases 1

• Actively ongoing ischemia or hemodynamic instability:

  • Consider PCI if feasible OR
  • Urgent CABG (based on technical considerations and local expertise) 1

2. Medical Management

• Aggressive anti-hypertensive therapy should be considered as hypertension is an independent predictor of recurrent SCAD 1
• Beta-blockers should be considered as they are significantly associated with reduced risk of recurrent SCAD 1
• Dual antiplatelet therapy (DAPT) may be used, though its benefit is questionable 1

3. Revascularization Considerations

The decision for revascularization must be individualized based on:

• Clinical presentation (ongoing ischemia, hemodynamic stability)
• Anatomical factors (location and extent of dissection)
• Technical considerations

Important caveat: PCI in SCAD carries risks of:

• Uncontrolled escalating coronary dissections
• Extension of intramural hematoma
• Acute coronary thrombosis after stenting 2

Special Considerations

1. Proximal dissections: These are considered high-risk anatomy, especially when involving the left main or proximal segments of major coronary arteries. While conservative management is generally preferred in SCAD, proximal dissections may warrant more aggressive intervention if they compromise a large territory of myocardium.

2. Monitoring period: Patients with SCAD should be monitored as inpatients for 3-5 days, even if managed conservatively, due to risk of extension of dissection or development of complications 1.

3. Long-term follow-up: After the acute event, patients should have:

   • Cardiac imaging to assess for healing
   • Screening for predisposing conditions (especially fibromuscular dysplasia)
   • Ongoing blood pressure control
   • Consideration of beta-blocker therapy 1

Pitfalls to Avoid

• Treating SCAD like typical atherosclerotic ACS: The pathophysiology is distinct, and standard ACS interventions may worsen outcomes in SCAD.
• Aggressive PCI without careful consideration: PCI in SCAD has higher complication rates than in atherosclerotic disease.
• Failure to screen for underlying conditions: Many SCAD patients have fibromuscular dysplasia or other predisposing conditions that require management.
• Inadequate follow-up: SCAD patients need close monitoring for recurrence and extension of dissection.

The management of SCAD requires careful consideration of the unique pathophysiology of this condition, which differs significantly from typical atherosclerotic coronary disease. While guidelines support a generally conservative approach, each case must be evaluated based on clinical stability, coronary anatomy, and the presence of ongoing ischemia.