What is the epidemiology of Spontaneous Coronary Artery Dissection (SCAD)?

Epidemiology of Spontaneous Coronary Artery Dissection (SCAD)

SCAD is an important cause of acute coronary syndrome in otherwise healthy young and middle-aged individuals, particularly women without traditional cardiovascular risk factors, accounting for 24-35% of all ACS cases in women ≤50 years of age. 1

Demographics and Prevalence

• Sex distribution: 87-95% of SCAD cases occur in women 1
• Age: Mean presentation age between 44-53 years 1
• Prevalence in ACS cohorts:
  • 0.1-0.7% of all ACS cases 1
  • 8.7-24.2% of ACS cases in women ≤50 years 1
  • 35% of ACS cases in women ≤50 years in some studies 1

Risk Factors and Associated Conditions

Hormonal Factors

• Pregnancy: Pregnancy-associated SCAD accounts for 5-17% of all SCAD cases and up to 43% of ACS cases during pregnancy 1
• Multiparity: Women with SCAD are more frequently multiparous 1
• Preeclampsia history: More common in women with SCAD 1

Vascular Conditions

• Fibromuscular dysplasia (FMD): Strong association with SCAD 1, 2
  • FMD was identified in 50% of femoral angiograms performed incidentally during SCAD management 3

Genetic Factors

• PHACTR1/EDN1 locus: The rs9349379-A variant increases risk of both SCAD and FMD 1
• Other genetic associations: Variants at chromosome 1q21.2, 12q13.3 in LRP1, and 21q22.11 near LINC00310 (in females only) 1

Precipitating Factors

• Physical triggers:
  • Extreme exertion: More common in men (44% of men vs 3% of women) 3
• Emotional triggers: Extreme emotional stress 4
• Hormonal triggers: Pregnancy, postpartum status (18% of female cases) 3

Clinical Presentation and Diagnosis

• Presentation: 49% present with ST-elevation myocardial infarction 3
• Vessel involvement:
  • Multivessel SCAD occurs in 23% of cases 3
  • Pregnancy-associated SCAD tends to have more severe features including left main/multivessel dissections 1

Prognosis and Outcomes

• In-hospital mortality: Low regardless of initial treatment 3
• Long-term outcomes:
  • Recurrence rate: SCAD recurs in 11-19% of patients 1
  • Estimated 10-year major adverse cardiac events rate: 47% 3
  • Recurrence typically affects new coronary artery segments 1

Risk Factors for Recurrence

• Coronary tortuosity: The only identified risk factor for SCAD recurrence 1
• Median time to recurrence: Variable across studies (42 days to 3.6 years) 1

Important Clinical Considerations

• SCAD patients typically have fewer traditional CAD risk factors compared to patients with atherosclerotic ACS 1
• SCAD is frequently underdiagnosed or misdiagnosed, requiring heightened clinical suspicion 1
• Management differs from typical atherosclerotic disease, with conservative management often preferred over intervention 4
• Percutaneous coronary intervention has high complication rates (35%) in SCAD patients 3

Understanding the unique epidemiology of SCAD is crucial for proper diagnosis and management, particularly in young women presenting with acute coronary syndrome who lack traditional cardiovascular risk factors.