Second Line Endovascular Treatment in Acute DVT

The goal of this study is to fill the paucity of second line endovascular treatment for acute deep venous thrombus (DVT) by using catheter-directed thrombolysis (CDT) and mechanical thrombectomy (MT) as adjunctive second-line treatments for acute DVT patients who show no improvement after an initial anticoagulation trial for one week. The main questions the study aims to answer are: \- Are adjunctive use of endovascular interventional treatments as second-line to DVT treatment safe and efficient? Participants will be followed with repeat US at 1 week after initial DVT to assess for response to anticoagulation treatment. If there is significant residual thrombus with minimal or no response to treatment, participants will be offered enrollment to the study in the office or inpatient setting. Enrolled participants will be randomized into control or intervention arms with 1:1 ratio. Researchers will compare follow-up Villalta and Marder scores between groups to see whether endovascular interventions are safe and efficient.