Increased D-Dimer Levels and Residual Venous Thrombosis Are Associated with Late Recurrence of Deep Venous Thrombosis

Background: Many patients present new thrombotic events even long-time after the first thrombotic episode and risk factors for recurrence in these cases are not fully elucidated.

Aim: To evaluate the risk of late recurrence of thrombosis after a first DVT episode.

Methods: This is a prospective observational study. We evaluated the association of D-dimer (DD) levels and persistent residual venous thrombosis (RVT), by Doppler ultrasound, with the occurrence of new thrombotic events long-time after the acute DVT episode.

Results: Fifty-six patients were enrolled for the study. For all patients, DVT episode occurred more than 12 months apart from the enrollment day. Median follow-up was 28 months. During the follow-up time, 10 patients presented thrombosis recurrence. Patients who suffered DVT recurrence had higher DD levels than those who did not had recurrence (median= 0.99 vs 0.40, respectively). The best cut-off value to discriminate those at risk for recurrence was DD > 0.63mg/L (area= 0.7380 95%CI= 0.5800 to 0.8961, P=0.01). Recurrence occurred in 27.7% of patients with previous DD>0.63mg/L and in 5.9% of patients with previous DD< 0.63mg/L (relative risk = 6.46; 95%CI 1.36- 30.52, P=0.007). New thrombosis events occurred only in patients with previously documented RVT, mainly in patients with hypoechoic RVT. During follow-up, new thrombotic events were diagnosed in 75% of patients with hypoechoic RVT. The relative risk for recurrence according to the presence of RVT was 9.129 (95% CI= 2.60-32.02, P<0.001). The presence of RVT also modified the effect of DD on the recurrence risk. Patients with DD > 0,63mg/L but without RVT had similar risk of recurrence than those with DD< 0.63mg/L, whereas the risk for recurrence increased in 14-15 times in patients with RVT.

Conclusion: These results suggests that the persistence of residual thrombosis combined with high levels of DD, long-time after the acute DVT, are risk factors associated with late thrombosis recurrence.