Antiphospholipid syndrome

Background

• APS definition (need 1 from each category):
  • Presence of at least 1 of the following: DVT, arterial thrombosis, or pregnancy morbidity (eg fetal loss, preterm)
  • Presence of at least 1 of the following antiphospholipid antibodies (aPL): lupus anticoagulant (LA), anticardiolipin (aCL), β2-glycoprotein-1 (β2-GP-1)

• APS can occur as a primary condition or in setting of underlying disease (eg SLE)

Pathophysiology

• Currently accepted theory: Susceptible pts (eg SLE) develop aPL after infection. After development of aPL, “second hit” stress required to develop full-blown APS. aPL affects coagulation by interacting with protein C, annexin V, platelets, proteases, tissue factor, and impairing finbrinolysis
  • “Second hit” stressors: smoking, prolonged immobilization, pregnancy, exogenous estrogen, malignancy, nephrotic syndrome, HTN, hyperlipidemia

Clinical Features

• Thrombocytopenia, increased PT/INR and aPTT
• Microangiopathic Hemolytic Anemia (MAHA)
• DVT/PE
• Fetal loss
• Heart valve disease
• aPL-nephropathy
• Stroke/TIA, other neuro sx
• Livedo reticularis

Diagnosis

• Presence of DVT, arterial thrombus, or pregnancy morbidity (eg fetal loss, preterm)
• Presence of aPL

Treatment

• Anticoagulation (unfractionated heparin, LMWH, or warfarin)
  • No benefit in treatment or prophy using ASA or plavix
  • Add hydroxychloroquine if pt has SLE
  • Warfarin contraindicated in pregnancy!

• IVIG, plasmapharesis, and steroids have not been proven to be of benefit in APS

Catastrophic APS Treatment

• Treat stress that preceipitated catastrophic APS (eg infection), anticoagulation, high dose steroids
  • If evidence of microangiopathy (thrombocytopenia, MAHA), add IVIG and plasma exchange to above regimen

Complications

• Catastrophic APS: widespread thrombotic disease w/ multiorgan failure precipitated by some stress (eg infection)

See Also

• DIC, TTP, HUS, Microangiopathic Hemolytic Anemia (MAHA)
• HELLP, Paroxysmal Nocturnal Hemoglobinuria (PNH), HIT