Thirty-two patients with acute, proximal-vein thrombosis were treated with 
heparin and alteplase (0.25 versus 0.5 mg/kg/24 h during 3-7 days) in a 
randomized, double-blind, multicenter, European (ETTT) trial. The treatment 
resulted in a decrease of the venographic Marder's score from 18 (6-25) to 13 
(2-24) units (median, range) in Group I (0.25 mg/kg/24 h, n = 15, median 
decrease 3.0, p = 0.32) and from 17.5 (3-33) to 15.5 (0-27) in Group II (0.5 
mg/kg/24 h, n = 16, median decrease 4.0, p = 0.23). Comparison of the sequential 
venograms could be performed in 14 cases of Group I and in 15 cases in Group II. 
A minority of patients showed substantial partial recanalization of the 
initially obstructed veins on the control venogram (one in each treatment group) 
and most of the control venograms showed either thrombus size reductions (5 in 
Group I, 7 in Group II) or no change or even deterioration (8 in Group I, 7 in 
Group II). Major bleedings were observed in 7 patients (7/32, 22%), 5 of them 
occurring in Group II (5/17, 29%). Thus, the results of the ETTT trial show that 
the used low dosages of alteplase administered intravenously over 3-7 days in 
heparinized patients cannot be recommended as a treatment for patients with deep 
venous thrombosis of lower limbs and/or pelvis. Further studies are needed to 
define a more suitable dosage regimen of alteplase in this indication.