Summary: Women with a history of venous thromboembolism (VTE), thrombophilia or both may be at increased risk of thrombosis during pregnancy, but the optimal management strategy is not well defined in clinical guidelines because of limited trial data. A strategy of risk assessment and heparin prophylaxis was evaluated in pregnant women at increased risk of VTE. In a prospective trial (Efficacy of Thromboprophylaxis as an Intervention during Gravidity [EThIG]), 810 pregnant women were assigned to one of three management strategies according to pre-defined risk factors related to history of VTE and thrombophilic profile. Low-risk women (group I), received 50–100 IU dalteparin/ kg body weight/ day for 14 days postpartum, or earlier when additional risk factors occurred. Women at high (group II) or very high risk (group III) received dalteparin from enrolment until six weeks postpartum (50–100 IU and 100–200 IU/ kg/ day, respectively). Objectively confirmed, symptomatic VTE occurred in 5/810 women (0.6%; 95% confidence interval [CI], 0.2 to 1.5%) (group I, 0 of 225; II, 3/469; III, 2/116). The rate of serious bleeding was 3.0% (95 % CI, 1.9 to 4.4%); 1.1% (95 % CI, 0.5 to 2.2%) was possibly dalteparin-related. There was no evidence of heparin- induced thrombocytopenia, one case of osteoporosis, and rates of miscarriage and stillbirth were similar to previous, retrospective studies. Risk-stratified heparin prophylaxis was associated with a low incidence of symptomatic VTE and few clinically important adverse events. Antepartum heparin prophylaxis is, therefore, warranted in pregnant women with idiopathic thrombosis or symptomatic thrombophilia.

The impact of residual vein thrombosis (RVT) on the long-term outcome of patients with deep vein thrombosis (DVT) is unknown. We assessed the incidence of recurrent venous thromboembolism (VTE), postthrombotic syndrome (PTS), arterial thrombotic events, and cancer in patients with DVT with and without RVT. For this purpose, we evaluated up to 3 years 869 consecutive patients with acute proximal DVT who had conventional anticoagulation. RVT, defined as ultrasound incompressibility of at least 4 mm in the common femoral and/or the popliteal vein after 3 months, was detected in 429 (49.4%) patients, and was more likely in males (adjusted odds ratio [OR], 1.82; 95% confidence interval [CI], 1.37–2.04), in patients with previous VTE (OR, 1.64; 95% CI, 1.06–2.54), and in those with extensive thrombosis (OR, 3.58; 95% CI, 2.19–5.86). During the 3-year follow-up, recurrent VTE developed in 84 (19.6%) patients with RVT and 43 (9.8%) patients without RVT (adjusted hazard ratio [HR], 2.03; 95% CI, 1.40–2.94); PTS in 225 (52.4%) and 118 (26.8%), respectively (HR, 2.34; 95% CI, 1.87–2.93); arterial thrombosis in 29 (6.7%) and 14 (3.2%), respectively (HR, 2.05; 95% CI, 1.08–3.88); and cancer in 21 (4.9%) and 8 (1.8%), respectively (HR, 3.09; 95% CI, 1.31–7.28). In conclusion, in patients treated with vitamin K antagonists for prevention of recurrent VTE, RVT doubles the risk of recurrent VTE, PTS, arterial thrombosis, and cancer. Males, patients with previous VTE, and those with extensive thrombosis are independent risk factors of RVT development. Studies addressing the impact of the novel direct anticoagulants on the development of RVT as well as the long-term complications of DVT are needed.