A very useful review was recently published in Blood, available as free full text.
Points of interest:
More than one third of patients with DVT will develop post thrombotic syndrome (PTS). 5-10% will develop severe PTS.
In patients who have had a DVT the differentiation between recurrent ipsilateral DVT and PTS is difficult. Venous duplex testing, D-dimer and clinical prediction tools can be helpful.
Which patients will develop PTS? Incomplete resolution of leg symptoms by 1 month is a strong predictor. Risk factors include age, obesity, common femoral or iliac (as opposed to distal femoral of popliteal) location, subtherapeutic INRs during the first three months of treatment and recurrent ipsilateral DVT are risk factors. Thrombophilia does not appear to be a risk.
Prevention is somewhat controversial. Fitted compression stockings (worn for 2 years) appear to cut the incidence in half although better quality data are needed. Thrombolytic therapy is controversial. Such therapy, particularly catheter directed thrombolytic therapy, can reduce the incidence of PTS but the supporting studies have limitations. Rigorous trials are underway. The Chest guidelines suggest that catheter directed thrombolytic therapy “may be considered” in cases of extensive DVT in otherwise appropriate patients (low bleeding risk, patient preference, etc).
The author recommends that risk assessment for PTS and counseling the patient concerning said risk be carried out.