Antiphospholipid syndrome (APS)

Classification Criteria – Revised Sapporo (Sydney 2006)

• The diagnosis of APS requires ≥ 1 clinical criterion AND ≥ 1 laboratory criterion:
• Clinical Criteria: Vascular thrombosis (deep vein thrombosis + pulmonary embolism + stroke + transient ischemic attack + peripheral arterial thrombosis + or thrombosis of any other vessel) or obstetric morbidity (≥ 1 unexplained fetal death ≥ 10 weeks of gestation with normal fetal morphology + or ≥ 3 unexplained consecutive spontaneous miscarriages) < 10 SA or ≥ 1 premature birth < 34 weeks' gestation secondary to severe preeclampsia or severe placental insufficiency
• Biological criteria (present ≥ 2 times at ≥ 12-week intervals): lupus anticoagulant (LA) positive or aCL IgG or IgM ≥ 40 GPL/MPL (or > 99th percentile) or anti-β2GP1 IgG or IgM > 99th percentile, with persistence over 2 measurements 12 weeks apart being mandatory to avoid diagnosing transient aPL (infections + medications) which do not constitute true APS.
• High-risk profile (triple positivity): Positivity of all 3 tests (lupus anticoagulant + anticardiolipin antibodies + anti-beta-2 glycoprotein 1 antibodies) = highest thrombotic risk + high risk of recurrence → lifelong anticoagulation often recommended

Clinical manifestations

• Venous thrombosis Deep vein thrombosis of the lower extremities ++ pulmonary embolism cerebral venous sinus thrombosis hepatic vein thrombosis (Budd-Chiari syndrome) renal vein thrombosis retinal vein thrombosis
• Arterial thromboses Ischemic stroke (particularly in young women) < 50 years old without classic risk factors → consider APS) + TIA + myocardial infarction (in young people) + arterial occlusion of limbs + retinal arterial thrombosis (amaurosis fugax + BRAO)
• Obstetric manifestations: recurrent fetal losses (recurrent spontaneous miscarriages + late-term stillbirth) + severe early-onset preeclampsia< 34 weeks gestational age) + HELLP syndrome + severe intrauterine growth restriction + due to placental vessel thrombosis
• Non-criteria manifestations (advanced SAPL): thrombocytopenia (20–50 % — platelets 50,000–150,000/µL) + valvular lesions (Libman-Sacks vegetations + valvular thickening + mitral or aortic insufficiency) + livedo reticularis (purplish skin network) + antiphospholipid nephropathy (renal thrombotic microangiopathy) + leg skin ulcers + refractory migraine

Catastrophic SAPL (CAPS)

• Definition: Multiple thromboses affecting three or more organs or vascular territories developing simultaneously or within less than a week, plus histology showing small vessel occlusions (thrombotic microangiopathy) and confirmed antiphospholipid antibodies.
• Triggering factors infection bactérienne (trigger le plus fréquent — 20 % des CAPS) + chirurgie + arrêt brutal de l'anticoagulation + médicaments + grossesse
• Manifestations: kidney failure (78 %) + lung damage (ARDS + 66 %) + brain damage (56 %) + heart damage (50 %) + severe thrombocytopenia + DIC + skin signs (livedo + necrosis)
• Treatment (triple therapy): IV anticoagulation (unfractionated heparin) + high-dose systemic corticosteroids (methylprednisolone 1 g/day × 3 days then prednisone 1–2 mg/kg/day) + plasma exchange and/or IV immunoglobulins → rituximab + eculizumab if refractory + 30–50% mortality % even with optimal treatment

Treatment — anticoagulation

SAPL and lupus - an important association

• Prevalence 30-40% of lupus patients have aPL+ and 50-70% of patients with secondary APS have lupus+ systematically screen for aPL in all lupus patients
• Hydroxychloroquine (Plaquenil®): Reduces the risk of thrombosis in lupus patients with aPL + mechanism: inhibition of platelet activation by aPL + anti-aggregating properties + immunomodulatory action → recommended for all lupus patients with positive aPL
• Lupus pregnancy + APS: Highly specialized care at a reference center + LMWH + aspirin + hydroxychloroquine (safe in pregnancy) + prednisone if active lupus + close obstetric monitoring (bi-monthly placental Doppler ultrasound + fetal monitoring)

Consult at Clinique Omicron

Clinique Omicron's physicians and nurse practitioners (NPs) screen for APS in patients with unexplained recurrent thromboses, recurrent miscarriages, or stroke in young women. They prescribe the complete aPL workup (LAC + aCL + anti-β2GP1) with repetition at 12 weeks to confirm persistence, initiate aspirin for primary prophylaxis, and warfarin for confirmed thromboses. They manage INR monitoring under warfarin, refer to rheumatology for lupus-related APS, and to specialized obstetrics for high-risk pregnancies. Consultations are available at several service points across Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.

The content of this page is for informational purposes only and does not replace the advice of a physician, rheumatologist, or hematologist. APS is a complex disease requiring long-term anticoagulation, the abrupt cessation of which can trigger catastrophic APS. Direct oral anticoagulants (DOACs) are NOT recommended as first-line treatment in thrombotic APS—warfarin remains the standard of care.