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Poster Networking

Women's Hemostasis and Thrombosis

PB0477 - Antithrombin deficiency in women: risk factors and management. A single-center experience

Sunday, June 23, 2024
13:45 – 14:45 ICT
Room: Exhibition Hall
Background: Antithrombin deficiency (ATD) is the strongest thrombophilia, can be acquired (AATD) or congenital (CATD). The prevalence of ATD in the general population ranges from 0.02% to 0.2%. The risk of venous thromboembolism (VTE) associated to ATD is also heterogeneous depending on the type of deficiency and combined factors, but the average odds ratio of VTE in ATD is 16.26. Two types of ATD were described: quantitative-type-I, with severe clinical phenotype (early, idiopathic, recurrent and important family history VTE) and qualitative-type-II, with three subtypes defined by the functional defect: reactive site defects (RS); heparin binding site (HBS) defects; and pleiotropic effect (PE) with both reactive and heparin binding defects.

Women with ATD increasing risk of VTE with to use combined estrogen/gestagen oral contraceptives (COC) and pregnancy/postpartum. Thromboprophylaxis is recommended in latest scenarios.

Aims: Clinical, biological and genetic characterization of the women with ATD identified in a single center for 4 years.

Methods: ATD was fully characterized by functional antigenic biochemical and genetic analysis. Clinical data were collected from their medical records.

Results: We identified five women with ATD (Table 1). Four had CATD, one severe caused by complete deletion of SERPINC1 causing type I deficiency, and one moderate type II ATD caused by an HBS variant (Budapest 3), and two by a mild RS variant (Cambridge II). Case-3 is AATD during the use of COC. VTE occurred in 2 cases of obesity with COC, but none related to pregnancy.
Three type II CATD women had 5 pregnancies (2: LMWH was administered the entire pregnancy and postpartum. 2: no used LMWH and 1: developed preeclampsia and intrauterine growth retardation)

Conclusion(s): Our study suggests a heterogeneous clinical impact of ATD in women that depends on the type of deficiency and the combination of risk factors, which must be considered for thromboprophylaxis during pregnancy.