Objective: In a previous study we demonstrated the beneficial effect o
f some venoactive drugs when administered to patients with established
post-thrombotic syndrome (PTS). The aim of the present study was to a
ssess prospectively the efficacy of one of such drugs in preventing th
e development of PTS signs. Design: Prospective, randomized, open stud
y. Patients: 100 consecutive patients with a first episode of deep vei
n thrombosis (DVT), whose diagnosis had been verified with either veno
graphy or real-time ultrasonography, were entered in the study. Interv
entions: In addition to anticoagulant therapy, and immediately prior t
o discharge, patients were randomly allocated to receive Hidrosmina (V
enosmil, FAES, Spain) 600 mg daily or no additional treatment. Each pa
tient was followed-up in our outpatient clinic at 4-monthly intervals
for a 3-year period. At each visit, patients were carefully examined f
or the presence of oedema, pigmentation, induration and ulceration. A
simple scoring system, as reported by the SVS and the ISCS, was used t
o assess the severity of symptoms and signs. Results: After excluding
17 patients with recurrent DVT, there remained 83 patients, 10 of whom
had bilateral DVT. No signs of PTS were found during the 3-year perio
d in 65 out of 93 limbs (70%). Class 1 signs were found in 21 out of 9
3 limbs (23%), class 2 in 6 out of 93 limbs (6%) and class 3 signs in
one limb. PTS was more commonly found in patients in whom DVT had invo
lved the popliteal vein (20/50 vs. 8/43; p<0.05). Furthermore, PTS dev
eloped in 7 out of 46 limbs (15%) in patients taking Hidrosmina vs. 21
out of 47 limbs (45%) in patients not taking the drug (p < 0.005). Co
nclusions: In this pilot study our findings demonstrate that long-term
therapy with Hidrosmina may be useful in preventing the development o
f PTS signs.