Iliac compression syndrome and recanalization of femoropopliteal and iliac venous thrombosis: A prospective study with magnetic resonance venography

Objectives. Poor iliac vein recanalization has been associated with compression of the left common iliac vein by the right common iliac artery (RCIA/LCIV compression); however, this finding has been difficult to confirm. In a baseline study, RCIA/LCIV compression was detected with magnetic resonance imaging in patients with deep venous thrombosis. We compared recanalization of left femoropopliteal and iliac thrombosis with and without RCIA/LCIV compression. Methods: This was a prospective blinded study carried out in a 1355-bed university hospital. Thirty-one patients were recruited from consecutive cohorts of patients with iliofemoral and femoropopliteal DVT who underwent direct thrombus magnetic resonance imaging, venous enhanced peak arterial magnetic resonance venography, and magnetic resonance arteriography as part of the baseline study relating RCIA/LCIV compression to extent of thrombosis. Magnetic resonance venography was performed 6 weeks, 6 months, and 1 year after diagnosis of deep venous thrombosis. Femoropopliteal and iliac venous segments that were occluded at diagnosis were classified as occluded, partially occluded, or patent on follow-up scans. Results: At 6-week follow-up, recanalization of all segments was incomplete. At both 6-month and 1-year follow-up, recanalization of left iliac segments associated with RCIA/LCIV compression was poorer compared with recanalization of left iliac segments not associated with compression (6 of 6 occluded vs 1 of 6 occluded and 1 of 6 partially occluded at 6 months, P =.015; 6 of 6 occluded vs 5 of 5 patent at I year, P =.002). This was due to complete failure of recanalization of left common iliac veins associated with RCIA/LCIV compression in 6 of 6 cases. All other iliac and femoropopliteal segments including left external iliac veins associated with RCIA/LCIV compression had high rates of recanalization at both 6 months and 1 year. Conclusion: RCIA/LCIV compression is associated with persistent occlusion of the left common iliac vein. The recanalization rate for all other femoropopliteal and iliac segments was high.