Effect of the anticoagulant therapy in the incidence of post-thrombotic syndrome and recurrent thromboembolism:: Comparative study of enoxaparin versus coumarin

Objective: We evaluated the effect of long-term anticoagulant treatment (enoxaparin vs coumarin) in patients with deep venous thrombosis (DVT) as to incidence of post-thrombotic syndrome (PTS) and recurrent venous thromboembolism. We also analyzed the impact of thrombus regression after the anticoagulant treatment for these two outcomes. Methods: A prospective study was designed in which 165 patients with symptomatic, unilateral, first-episode DVT were randomized to a long-term anticoagulant treatment with coumarin or enoxaparin during at least 3 months. The rate of thrombus regression was defined as the difference in Marder score after 3 months of treatment by venography. Follow-up was performed at 3, 6, and 12 months, and yearly thereafter for 5 years. Venous disease was related to pathologic severity of PTS according to the validated scale of Villalta as rated by a physician blinded to treatment. Recurrence of symptomatic venous thromboembolism was documented objectively. Results. The 5-year follow-up period was completed for 100 patients (enoxaparin, 56; coumarin, 44). A lesser incidence of PTS was observed in the enoxaparin group (39.3% absent, 19.6% severe) than in the coumarin group (29.5% absent, 29.5% severe), although this difference was not statistically significant. The accumulated recurrence rate was 19.3% with enoxaparin compared with 36.6% with coumarin (P =.02). Although the mean Marder score was significantly improved in both groups (49.1% for enoxaparin vs 24.0% for coumarin; P =.016), a lower reduction in thrombus size was associated with higher clinical events of recurrence (hazard ratio = 1.97; 95% CI, 1.06-3.66; P =.032). A significant inverse correlation was also found between the degree of thrombus regression at 3 months and the incidence at 5 years of PTS (P =.007). Conclusions: Residual venous thrombosis is an important risk factor for recurrent thromboembolism and PTS. A greater reduction in thrombus size was associated with lesser clinical events of recurrence and consequently a lesser rate of PTS. However, despite a greater recanalization with enoxaparin, the incidence of PTS was similar between both treatment groups, probably because of the small sample size. Further investigations are needed to clarify the implication of the anticoagulant treatment in the severity of PTS.