PROfunda Femoris Vein Thrombosis Evaluation and Clearance to Improve Outcomes of Endovascular Treatment for Acute Iliofemoral Deep Vein Thrombosis

PROfunda Femoris Vein Thrombosis Evaluation and Clearance to Improve Outcomes of Endovascular Treatment for Acute Iliofemoral Deep Vein Thrombosis: a Multicenter Randomized Controlled Study (The PROTECT Study)

Patients with iliofemoral vein thrombosis are prone to developing post-thrombotic syndrome (PTS). The profunda femoris vein (PFV) is an important inflow of the iliofemoral vein. Profunda femoris vein thrombosis clearance (PFV-TC) may improve the patency of iliofemoral vein and reduce the occurrence of PTS.

Acute lower extremity deep vein thrombosis (DVT) can lead to obstruction of veins, causing sudden lower limb swelling. Patients may also develop post-thrombotic syndrome (PTS) manifesting as recurrent lower limb swelling, skin disorders, and even non-healing ulcers, which severely affects the patient's quality of life. Among lower extremity DVT, thrombosis involving the iliofemoral veins is the most severe, with an incidence of PTS as high as 20%-50%. Percutaneous mechanical thrombectomy (PMT) utilizes mechanical aspiration to rapidly remove thrombus, relieve venous obstruction, and restore luminal patency. According to the results of a prospective clinical study, PMT can effectively improve the primary thrombus clearance rate and shorten hospital stay in patients with DVT. Among 329 patients, 192 (58.5%) achieved complete thrombus removal using the AngioJet catheter. PMT was once considered to be the first-line treatment option for DVT. However, the results of the ATTRACT study, published in 2017 in New England Journal of Medicine, sparked considerable controversy regarding the use of PMT for DVT. The ATTRACT study found that there was no significant difference in the incidence of PTS at two years after PMT compared with anticoagulation alone. Although PMT can rapidly remove thrombus, is it unable to improve the long-term outcomes for patients with DVT? According to previous studies, the primary patency rate at 12 months after PMT for acute iliofemoral venous thrombosis ranges from 77% to 85%, while the incidence of PTS at 24 months postoperatively is as high as 40%. Residual thrombus is an important cause of thrombus recurrence, re-occlusion of the vein, and poor clinical outcomes. Previous studies have primarily focused on thrombus clearance in the popliteal vein, superficial femoral vein, common femoral vein, and iliac vein, while neglecting the assessment and clearance of profunda femoris vein (PFV) thrombosis. As the PFV is an important inflow of the iliofemoral vein, whether PFV-TC can improve the patency rate and clinical outcomes of endovascular treatment for acute iliofemoral DVT remains unclear. In a preliminary study, the investigators analyzed and compared two cohorts: one receiving conventional endovascular treatment for acute iliofemoral venous thrombosis, and the other receiving conventional treatment combined with Profunda femoris vein thrombosis clearance (PFV-TC). The results showed that the 24-month patency rate of the iliofemoral vein was 90% vs. 72%, and the incidence of PTS was 11% vs. 32% (P<0.05). These findings were published in November 2025 in European Journal of Vascular and Endovascular Surgery. This study has garnered widespread attention, and de Wolf MAF published an invited commentary on this study, acknowledging the value of this approach in the endovascular treatment of acute iliofemoral DVT. Therefore, the investigators hypothesize that PFV-TC can improve inflow and reduce the incidence of PTS for iliofemoral DVT. However, high-level evidence is still lacking. The present study is a prospective, multicenter, randomized, open-label, evaluator-blinded, 1:1 parallel-controlled clinical trial investigating PFV-TC, aiming to obtain higher-level evidence to guide endovascular treatment of acute iliofemoral DVT.

Inclusion Criteria:

1. Age ≥ 18 years and ≤ 85 years;
2. Diagnosed with acute iliofemoral DVT involving iliac vein, common femoral vein, and PFV (confirmed by preoperative ultrasound, CT venography, or pre-procedural venography);
3. Time from symptom onset to endovascular treatment ≤ 14 days;
4. Patient receives endovascular treatment with PMT;
5. Patient provides written informed consent.

Exclusion Criteria:

1. Presence of pre-existing PTS in the limb scheduled for treatment, or a history of symptomatic DVT in the same limb;
2. Concurrent symptomatic acute DVT involving the iliac vein and/or common femoral vein in the contralateral limb;
3. Known allergy to heparin, low-molecular-weight heparin, contrast media, or other relevant agents;
4. Concomitant severe pulmonary embolism with hemodynamic compromise, such as hypoxia or hypotension;
5. Intolerance to endovascular intervention due to concurrent acute systemic illness, severe dyspnea, or other contraindications;
6. Concomitant severe renal insufficiency with creatinine clearance < 30 ml/min;
7. Presence of active bleeding, severe hepatic insufficiency, bleeding diathesis, or other coagulation disorders;
8. Concomitant severe anemia (hemoglobin < 8.0 mg/dL) or thrombocytopenia (platelet count < 80,000/mL);
9. History of subarachnoid hemorrhage, intracranial hemorrhage, intracranial vascular malformation, or intracranial aneurysm;
10. Pregnancy;
11. Presence of other diseases (e.g., advanced malignancy, cardiac insufficiency) with an estimated life expectancy < 24 months;
12. Participation in another clinical trial of a drug or medical device within the past 1 month that may interfere with the present study;
13. Unwillingness to participate in this trial.