Arterial thrombosis is a clot that forms within an artery. It is particularly dangerous as it impairs perfusion to organs. It is the cause of myocardial infarctions,
strokes, TIA, PAD etc.
⚠️ Risk factors
- Atherosclerosis
- Smoking
- Alcohol misuse
- Obesity
- Sedentary lifestyle
- Diabetes mellitus
- Hypertension
In this CCC we will cover antiphospholipid syndrome which is another cause for arterial thrombosis. The other conditions such as MI, stroke, TIA, PAD etc. will be covered separately.
Pathophysiology
Antiphospholipid antibodies (aPLs) are autoantibodies that attack phospholipid-binding plasma proteins such as prothrombin, as well as the phospholipids that are expressed on platelets, monocytes and trophoblast cells. This leads to hypercoagulability, complications in pregnancy (particularly recurrent miscarriage).
It is not known what causes the development of these antibodies, but it is proposed to be molecular mimicry from bacterial/viral infection.
It may also occur secondary to other autoimmune conditions such as SLE.
Antiphospholipid antibodies that may be useful to remember include:
- Lupus anticoagulant
- Anticardiolipin antibodies
- Anti-beta2-glycoprotein I antibodies
😷 Presentation
- History of VTE
- Pulmonary embolism
- DVT
- History of arterial thrombosis
- Stroke
- MI
- Renal thrombosis
- Pregnancy complications
- Recurrent miscarriage
- Stillbirth
- Preeclampsia
- Livedo reticularis - a purple, lace-like rash that gives a mottled purplish discolouration to the skin. It may be blanching or non-blanching. It occurs due to fibrin deposition at the periphery of arterioles.
- Thrombocytopenia
- Libmann-Sachs endocarditis - vegetations on the valves of the heart. It is a type of non-bacterial endocarditis. Mostly affecting the mitral valve.
- Prolonged aPTT
🔍 Investigations
The diagnosis based on the history of thrombosis/complicated pregnancy + detection of antibodies:
- Lupus anticoagulant - based on coagulation assays.
- Anticardiolipin antibodies
- Anti-beta2-glycoprotein I antibodies
- ANA antibodies, dsDNA, nuclear antigen antibodies - suggests SLE which is associated with the disease.
Other investigations to include are:
- FBC - may show thrombocytopenia.
- Creatinine and urea - to assess renal function. Microangiopathic thrombosis secondary to APS can sometimes lead to oedema and proteinuria in the patient.
🧰 Management
Management of the patients can be complex and may involve rheumatology, haematology, and obstetrics.
- Primary thromboprophylaxis (if the patient has not had a thrombosis and has been diagnosed with APLS) → low-dose aspirin.
- Secondary thromboprophylaxis requires lifelong warfarin with a target INR of 2-3.
- If the patient has recurrent VTE whilst on warfarin → add low-dose aspirin and increase INR target to 3-4.
- Pregnant women are started on LMWHs such as dalteparin or enoxaparin.
🚨 An acute thrombosis should be treated with LMWHs such as dalteparin or enoxaparin.