Residual venous thrombosis as a predictive factor of recurrent venous thromboembolism.
BACKGROUND
The optimum duration of anticoagulant therapy after an episode of deep venous thrombosis (DVT) is controversial. Contributing to the controversy is uncertainty about whether residual venous thrombosis, as assessed by repeated ultrasonography over time, increases the risk for recurrent thromboembolism.


OBJECTIVE
To determine the risk for recurrent thromboembolism in patients who have persistent residual thrombosis compared with patients who have early vein recanalization.


METHODS
Prospective cohort study.


METHODS
A university hospital in Padua, Italy.


METHODS
313 consecutive symptomatic outpatients with proximal DVT who received conventional short-term anticoagulation.


METHODS
Ultrasonographic assessment of the common femoral and popliteal veins was performed 3 months after acute DVT in all patients and at 6, 12, 24, and 36 months in patients found to have residual venous thrombosis. Veins were considered recanalized if they were 2.0 mm or less in diameter on a single test or 3.0 mm or less in diameter on two consecutive tests. Recurrent thromboembolism was assessed during a 6-year period.


RESULTS
The cumulative incidence of normal results on ultrasonography was 38.8% at 6 months, 58.1% at 12 months, 69.3% at 24 months, and 73.8% at 36 months. Of 58 recurrent episodes, 41 occurred while the patient had residual thrombosis. The hazard ratio for recurrent thromboembolism was 2.4 (95% CI, 1.3 to 4.4; P = 0.004) for patients with persistent residual thrombosis versus those with early vein recanalization.


CONCLUSIONS
Residual venous thrombosis is an important risk factor for recurrent thromboembolism. Ultrasonographic assessment of residual venous thrombosis may help clinicians modify the duration of anticoagulation in patients with DVT.
Prandoni
Paolo
P
Department of Medical and Surgical Sciences, University of Padua, Via Ospedale Civile 105, 35128 Padua, Italy. paoprand@tin.it
Lensing
Anthonie W A
AW
Prins
Martin H
MH
Bernardi
Enrico
E
Marchiori
Antonio
A
Bagatella
Paola
P
Frulla
Michela
M
Mosena
Laura
L
Tormene
Daniela
D
Piccioli
Andrea
A
Simioni
Paolo
P
Girolami
Antonio
A
D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use; D004334:Drug Administration Schedule; D005268:Femoral Vein / Q000000981:diagnostic imaging; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D011152:Popliteal Vein / Q000000981:diagnostic imaging; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012008:Recurrence; D012307:Risk Factors; D014463:Ultrasonography; D014654:Vascular Patency; D020246:Venous Thrombosis / Q000175:diagnosis* / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000453:epidemiology
D000925:Anticoagulants