A study presented at the American Society of Hematology Meeting in San Diego, USA by professor Per Morten Sandset at the Department of Hematology at Oslo University Hospital Rikshospitalet in Oslo, Norway and his team has shown that deep vein thrombosis (DVT) leads to the development of complications (post-thrombotic syndrome) in nearly half of DVT patients. The study, published Online First in The Lancet demonstrates that the rate of these complications can be reduced by about a quarter through a catheter-directed additional thrombolysis.

1 in 1,000 person per population per year will experience an acute deep vein thrombosis (DVT) of the lower limbs that is linked to significant risk of morbidity and mortality. Many patients develop a venous dysfunction that results in post-thrombotic syndrome (PTS) despite receiving anticoagulation treatments that effectively prevents thrombus extension, recurrence, pulmonary embolism and death. The characteristics of PTS are swelling, pain, a sensation of heaviness, pigmentation, oedema and skin deterioration of the affected limb, as well as venous ulcers in severe cases.

Researchers conducted a randomized, controlled trial on 209 patients between the ages of 18 to 75 years, who had a first-time iliofemoral DVT within 21 days from symptom onset. They randomly assigned 108 patients to receive conventional treatment alone, whilst 101 patients received conventional treatment with additional CDT. The primary outcome was frequency of PTS with researchers examining patients using a validated and recommended scoring system, known as the Villalta score, at 24-months. In addition they also checked patients for the presence of open vessels after 6 months, allowing the limb to function (iliofemoral patency).

After completion of the 24-months follow up, data for clinical status were available for 90% or 189 patients, i.e. for 99 patients in the conventional treatment alone group and 90 patients in the conventional treatment plus CDT group. The researchers discovered at 24 months that 37 or 41% of patients in the additional CDT group had developed PTS compared with 55 patients or 56% in the control group. This means that one case of PTS was avoided in every seven cases of those treated with catheter-directed alteplase. 58 of patients (66%) in the additional CDT group reported iliofemoral patency after 6 months of treatment compared with 45 patients or 47% in the control group. The researchers reported 20 complications through bleeding linked to CDT, which included three major and five clinically significant bleedings.

The researchers explain and conclude:

“Additional thrombolytic treatment reduced post-thrombotic syndrome compared with anticoagulation alone, but was associated with a small additional risk of bleeding. By contrast with systemic thrombolytic treatment, this bleeding risk seems acceptable, and the effect size was in line with results for systemic treatment.

Our findings support recent guidelines and catheter-directed thrombolysis should be considered in patients with high proximal deep vein thrombosis and low risk of bleeding. Our findings are promising and supplement the scarce and weak documentation on prevention of PTS. We believe that our result is an important contribution to the evidence base for treatment of severe DVT and should be taken into account when clinical guidelines are revised.”

Dr Lawrence ‘Rusty’ Hofmann and Dr William T Kuo from the Division of Interventional Radiology at Stanford University School of Medicine in California, USA, write in a linked comment:

“We congratulate Sandset and colleagues for a tremendous contribution to the published literature on DVT. Their pivotal trial data will help to preserve limb function in many patients with DVT by reducing the risk of incurable and debilitating post-thrombotic syndrome. Their trial thereby serves as a powerful motivation to undertake CDT for symptomatic acute lower extremity DVT.”

Written by Petra Rattue