All major trials to-date provide strong evidence that, for the initial
treatment of DVT, adjusted-dose LMWHs are at least as effective and s
afe as unfractionated heparin (UFH). When compared with UFH, LMWHs ach
ieved better thrombus lysis and had less bleeding complications (21-91
% risk reduction) and mortality (51% reduction). They also reduced the
incidence of recurrent DVT and PE at 90 days follow-up while there wa
s no need for monitoring. Despite these exciting findings however long
-term evaluation of mortality rate, recurrent venous thromboembolism,
blood monitoring tests efficacy and thrombus propagation/reduction are
open issues. Furthermore, venous haemodynamics have never been tested
. There is an ongoing Canadian study today, aiming to determine LMWHs
effectiveness in reducing death, recurrent venous thromboembolism and
haemorrhagic complications; it is obvious however that further studies
are needed. We must determine if a prologned use of LMWHs (i.e. 90 da
ys) is more effective in preventing the post-thrombotic sequelae, redu
cing also the incidence of haemorrhagic complications; we also need to
know the nature of the haematological changes that develop and the re
lationship between these changes and the recurrence rate; and finally,
we must identify effective blood tests to monitor this treatment.