Endovascular thrombus removal for acute iliofemoral deep vein thrombosis: analysis from a stratified multicenter randomized trial. Circulation 2018 Dec 4. Doi:10.1161/CIRCULATIONAHA.118.037425
This is a subgroup analysis of the previously published Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-directed Thrombolysis (ATTRACT) trial. ATTRACT is the latest and largest randomized controlled trial comparing the effectiveness of endovascular treatment of acute proximal deep venous thrombosis (DVT) with conservative treatment with respect to the occurrence of the postthrombotic syndrome (PTS) during follow-up. In ATTRACT, 692 patients with acute DVT (<14 days) were randomized to receive pharmacomechanical catheter-directed thrombolysis (PCDT) followed by oral anticoagulation (OAC) versus OAC only. The primary endpoint, the occurrence of the PTS during the follow–up period of 2 years, was assessed by determining the Villalta score (a score ≥ 5 was defined as presence of the PTS).
In ATTRACT, the authors found no difference in the prevalence of the PTS between both treatment groups during follow-up. After publication, the ATTRACT trial was matter of a controversial debate bringing up several points of criticism. One of the most crucial points of discussion referred to the included “mixed” study collective of DVT patients: in ATTRACT, patients with iliofemoral and patients with femoropopliteal DVT were included. After DVT, however, the risk of the development of the PTS, substantially depends on the primary location of thrombosis. Femoropopliteal DVT is associated with a low risk of developing a PTS, while patients with iliofemoral DVT face a much higher risk for this late thrombosis complication.
To address this controversy on the inhomogeneous study collective of ATTRACT, the current subgroup analysis evaluated outcomes in 391 patients with iliofemoral DVT only (total collective N=692 patients). This subgroup analysis found no difference in the occurrence of “any” PTS as assessed by the presence of a Villalta score ≥ 5. The occurrence of a moderate-or-severe PTS (defined as Villalta score ≥ 10), however, was significantly lower in the PCDT group than in conservatively treated patients. Regarding the risk of the development of a moderate-or-severe PTS the greatest benefit from PCDT was observed in younger patients (age <65 years) and in patients with major risk factors for DVT.
Importantly, when comparing the severity of PTS between the two study groups (PCDT vs. OAC only) by analyzing both (continuous) scales, the Villalta score and the Venous Clinical Severity Score (VCSS), as continuous variables (instead of comparing binary outcomes), PTS severity was significantly lower in the PCDT group. In addition, leg circumference, leg pain (as assessed by a 7-point Likert scale) and disease-specific quality of life (as assessed by VEINES-QOL) were significantly lower in the PCDT group.
The authors of this subgroup analysis concluded that, PCDT did not influence the occurrence of PTS, however, PCDT reduced the proportion of patients with a moderate-or-severe PTS and contributed to a significant reduction of leg symptoms and quality of life.
As critical comment, it should be added that the statistical power of this post-hoc analysis might still be too low for a definitive conclusion on PCDT in patients with acute iliofemoral DVT. Further, it also can be questioned, whether the use of the continuous Villalta score as binary outcome parameter is the adequate choice for the primary study endpoint. Finally, additional points of criticism, that were brought up after the first publication of ATTRACT, such as the low stent rate, still remain relevant.
Therefore, the authors claim further studies that are targeted on endovascular treatment of patients with iliofemoral DVT.