Background Post thrombotic syndrome (PTS) refers to manifestations of chronic venous insufficiency (CVI) after a deep vein thrombosis (DVT). The risk of developing moderate-severe PTS in the very long-term is largely unknown and particularly in case of distal DVT. Furthermore, the impact of DVT vs. other causes of CVI on long-term manifestations of PTS is also unknown. Objectives To assess the very long-term risk of moderate-severe PTS after DVT and the role that DVT plays in PTS symptoms. Patients/Methods Patients with lower limb DVT enrolled in the multicenter OPTIMEV study underwent a very long-term telephone follow-up. We assessed: i) the proportion of moderatesevere PTS (assessed with the patient-reported Villalta score) according to DVT extent and, ii) the population attributable fraction (PAF) that DVT plays in patients moderate-severe PTS manifestations. Results 14 years after DVT, moderate-severe PTS developed in 35 of 185 patients with distal DVT (18.9%[95%CI: 13.5% ; 25.3%], 11 of 47 patients with popliteal DVT (23.4%[12.3% ; 38.0%]) and 27 of 74 patients with ilio-femoral DVT (36.5%[25.6% ; 48.5%]). The PAF of DVT in moderate-severe symptoms of PTS, was respectively, 25.7%[-18.1% ; 53.3%] in patients with distal DVT, 27.3%[-63.7% ; 67.7%] in patients with popliteal DVT and 43.1%[+0.7% ; 67.4%] in patients with ilio-femoral DVT. Conclusion In the very long-term after DVT, a quarter of patients have moderate-severe PTS manifestations. However, the impact of the DVT on these manifestations appears nonpredominant and varies according to DVT extent. Distal DVT does not significantly increase the risk of developing moderate-severe PTS.