PB0976 - The first VTE and relapse pattern in inherited thrombophilia

Background: Inherited thrombophilia is associated with a high risk of venous thrombosis, but the choice of anticoagulant and treatment duration is individualized.

Aims: In this study, we aimed to delineate the characteristics of initial venous thromboembolism (VTE) event, treatment and relapse pattern in inherited thrombophilia.

Methods: Retrospective analysis was conducted on the patients who was diagnosed with inherited thrombophilia and experienced thromboembolic event in a single tertiary center.

Results: From May 2003 to January 2023, we identified 61 patients with inherited thrombophilia who experienced index VTE events. The median age of patients was 36 years (range, 11 – 74) with 42 male patients (68.9%). The most common diagnosis was protein S deficiency (n=32, 52.5%) followed by protein C deficiency (n=20, 32.8%) and antithrombin deficiency (n=9, 14.7%). Of them, 46 patients (75.4%) were diagnosed with pulmonary embolism (PE) and/or deep vein thrombosis, while 2 patients (3.3%) experienced cerebral venous sinus thrombosis, and 12 patients (19.7%) experienced splanchnic vein thrombosis. One patient (1.6%) was diagnosed with both DVT and SVT at the index event.
Among 55 patients whose medical information of initial anticoagulation was available, the median days on anticoagulation was 597 days (range, 29 – 9843). Except for 1 patient who was not a candidate for anticoagulation because of the chronicity of SVT, 40 patients (65.0%) discontinued anticoagulation (physician’s discretion, n=16; lost to follow up, n=7; patients’ will, n=6; development of new thrombosis, n=1; bleeding, n=5, unknown, n=4). Among them, 23 patients (57.5%) experienced recurrence. There was no apparent secondary risk factor at the diagnosis of their subsequent VTE event except for 9 patients (39.1%) with obesity.

Conclusion(s): Patients with inherited risk factors for VTE had a significant risk of recurrent VTE after the discontinuation of anticoagulation. Indefinite anticoagulation should be strongly considered without obvious secondary cause or bleeding risk.