Thrombosis and Antiphospholipid Syndrome

Introduction

Thrombosis and antiphospholipid syndrome are conditions characterized by the formation of blood clots in the deep veins, with a significant risk of pulmonary embolism, as noted by the American College of Chest Physicians and the American Heart Association 1, 2

The American Heart Association recommends testing for lupus anticoagulant as a more specific test for antiphospholipid syndrome, while anticardiolipin antibodies (IgG, IgM, IgA) are more prevalent but less specific for antiphospholipid syndrome 3, 4
Elevated homocysteine levels are associated with both venous and arterial thrombosis, according to the American College of Cardiology 3, 4
Elevated factor VIII levels and von Willebrand factor (vWF) levels may contribute to thrombotic risk, as reported by the American Heart Association 5

Hypercoagulable states are more strongly associated with venous thromboembolism than arterial thrombosis, with an annual incidence of 1-2 per 1000 individuals, as stated by the American College of Cardiology and the American Heart Association 3, 4, 2
The presence of genetic mutations, such as Factor V Leiden (G1691A) and prothrombin G20210A, can increase the risk of VTE, with a 2-4 fold increased risk associated with family history alone, as reported by the American College of Medical Genetics and Genomics 1, 2
Heterozygotes (one copy) have a 3-7 fold increased risk of venous thrombosis, while homozygotes (two copies) have an approximately 18 times higher risk of initial VTE, as noted by the American College of Medical Genetics 1
The mutation of Factor V Leiden (G1691A) is responsible for 90-95% of cases of activated protein C resistance, and the prothrombin G20210A variant is present in 1-2% of the general population, as reported by the American College of Medical Genetics and Genomics 1

The patient's thrombotic risk should be considered low based on the absence of genetic mutations and normal immunologic test results, but standard thromboprophylaxis should be used in high-risk situations, such as surgery or prolonged immobilization, as recommended by the American College of Chest Physicians and the American College of Medical Genetics and Genomics 1
Decisions regarding anticoagulation should be based on individualized assessment of thrombosis recurrence risk versus bleeding risk, taking into account the presence of Factor V Leiden and other thrombophilic factors, as noted by the American College of Medical Genetics 1
The optimal duration of anticoagulation should be based on clinical risks rather than thrombophilia test results, and anticoagulants are effective for treatment of DVT regardless of underlying thrombophilia status, as recommended by the American College of Medical Genetics 1

A comprehensive panel, including genetic tests (e.g. Factor V Leiden, prothrombin G20210A variant) and functional coagulation assays (e.g. protein C, protein S, antithrombin III deficiencies, antiphospholipid antibodies), should be ordered when testing is indicated, as suggested by the American College of Medical Genetics and Genomics and the American College of Hepatology 1, 6
The American College of Medical Genetics recommends limiting hereditary thrombophilia testing to patients with a history of venous thromboembolism, especially those under 50 years old, and to family members of patients with confirmed thrombophilia, even if they are asymptomatic, as noted by the American College of Medical Genetics and Genomics 1
Random screening of the general population for thrombophilia is not recommended due to limited cost-effectiveness, as stated by the American College of Medical Genetics and Genomics 1

Patients with Budd-Chiari syndrome or portal vein thrombosis should be considered for testing for both inherited and acquired thrombophilias, including JAK2V617F mutation testing, as recommended by the American College of Hepatology 6
Heterozygous Factor V Leiden or prothrombin 20210A mutation alone generally do not warrant extended anticoagulation based on current evidence, as noted by the European Society of Cardiology 7
Direct oral anticoagulants (DOACs) can interfere with several thrombophilia tests, particularly antithrombin activity assays and coagulation-based tests for proteins C and S, leading to overestimation of results and false negatives, as reported by the American College of Medical Genetics and Genomics 1
Positive test results can have psychosocial effects and insurance implications, as noted by the American Heart Association 2