Residual Vein Thrombosis After Deep Vein Thrombosis in Patients Treated with DOACs: Incidence and Associated Factors

<b>Background/Objectives:</b> After an initial course of anticoagulation for deep vein thrombosis (DVT), identifying patients at higher risk of recurrence remains a clinical challenge. The role of residual vein thrombosis (RVT) in this setting is still debated, as most available evidence derives from retrospective studies or from the Warfarin era. We conducted a study to evaluate the incidence of RVT in patients treated with direct oral anticoagulants (DOACs) and to identify the clinical factors associated with its persistence. We also compared the outcomes from the two most prescribed drugs in Italy, Apixaban and Rivaroxaban. <b>Methods:</b> A total of 113 patients with newly diagnosed DVT underwent follow-up visits at 6 weeks (T1), 3 months (T2) and 6 months (T3) after diagnosis. RVT was assessed by compression ultrasonography and clinical, family and pathological history data were collected. Ninety-six patients were included in the final statistical analysis. <b>Results:</b> RVT was detected in 68.2%, 52.1% and 37.7% of patients at T1, T2 and T3, respectively. Factors significantly associated with RVT at T2 were male sex, femoral vein involvement and a family history of DVT. No significant differences were observed between Apixaban and Rivaroxaban. Prior episodes of thrombosis, smoking, diabetes and obesity were not associated with RVT at 3 months. <b>Conclusions:</b> Our findings confirm that RVT rates progressively decrease over time, as previously observed in the Coumarins era, but suggest a stronger early response to DOACs, particularly during the first three months of therapy. Moreover, DOACs appear to provide more effective protection in patients with risk factors for venous disease.