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Thrombosis
Management Based on Residual Vein Thrombosis to Optimise the Duration of
Oral Anticoagulants After Deep Vein Thrombosis
a report by
Sergio Siragusa
Haematology Department, University Hospital of Palermo
In patients with a first episode of deep vein thrombosis (DVT) of the lower The experiences of two groups have been published.
13,14
Prandoni et
limbs, the standard for establishing the duration of oral anticoagulant al. evaluated 538 consecutive patients with acute proximal DVT who
therapy (OAT) is based on the nature of the DVT. It is currently three to six were randomised to receive either a flexible duration of OAT (up to
months for idiopathic DVT and three months for provoked thrombosis.
1
one year in patients with secondary DVT and two years in those with
Long-term anticoagulant treatment is highly effective in preventing idiopathic DVT) based on the persistence or regression of ultrasound-
recurrent venous thromboembolism (VTE), but this is associated with an confirmed residual thrombi at regular follow-up visits, or a fixed
increased risk of major bleeding that may offset the benefits of duration (three months in patients with secondary DVT and six months
anticoagulation.
2–6
The eighth edition of the American College of Chest in those with idiopathic DVT). All patients were followed up to three
Physicians (ACCP) clinical practice guidelines
7
on antithrombotic therapy for years to assess the development of recurrent VTE. During the three-
venous thromboembolic diseases stated that patients with a first episode of year follow-up period, recurrent VTE developed in 32 of the 271
idiopathic DVT should be treated for at least three months and then patients (11.8%) randomised to the flexible duration, and in 46 of the
evaluated for the risk–benefit ratio of prolonged anticoagulation. Most 267 (17.2%) randomised to the fixed duration. In a multivariate
patients with idiopathic DVT will not require prolonged OAT, but their analysis including age, gender, type of DVT, clinical symptoms of
identification is difficult.
7
New parameters have been proposed to classify a pulmonary embolism and thrombophilia, the hazard ratio of
patient’s risk of recurrent thrombosis. Of these, D-dimer and residual vein developing recurrent VTE in patients randomised to the flexible
thrombosis (RVT) have been more extensively evaluated.
8–10
duration of OAT compared with those allocated to the fixed duration
of OAT was 0.62 (95% confidence interval [CI] 0.39–0.97; p=0.036).
RVT expresses the persistence of venous thrombus over time. This When the effect and the duration of OAT were included in the model,
parameter is usually detected by compression ultrasonography (C-US), the hazard ratio became 0.79 (95% CI 0.5–1.26; p=0.32). During the
which is the standard method for diagnosing proximal DVT of the period of anticoagulation, clinically relevant bleeding developed in
lower limbs.
11
In earlier prospective studies conducted in patients with four patients (1.5%) randomised to the flexible duration of OAT, and
symptomatic DVT, the presence of a residual thrombus was associated in two patients (0.7%) allocated to the fixed duration.
with an increased risk of thrombotic recurrence in both idiopathic and
provoked venous thrombosis.
9,10
Recurrent events occurred not only in It is concluded that tailoring the duration of anticoagulation based on the
the previously affected veins but also in other sites, suggesting that persistence of residual thrombi reduces the rate of recurrent VTE without
residual thrombus may indicate an underlying prothrombotic state.
9,10
an appreciable increase in the haemorrhagic risk.
Based on these observations, D-dimer and RVT have been evaluated for In our studies, we used a standard time of three months after the
optimising OAT duration.
12,13
Results from these investigations showed index DVT to assess RVT. Figure 1 is the reported study design of the
that patients with persistent RVT, or positive D-dimer, are clearly in need first randomised trial.
13
Patients with RVT were randomised to either
of long-term anticoagulation, while in those in whom such markers stop or continue OAT (international normalised ratio [INR] 2.0–3.0) for
become normal OAT can be safely withdrawn after a few months. nine additional months (groups A2 and A1). Those without RVT did
not continue anticoagulation (group B). RVT detection is reported
The main advantage of using such markers relies on the possibility of in Figure 2.
assessing the patient’s risk, thus allowing the duration of individual
anticoagulation to be determined. Here we report and discuss the C-US of the affected leg was performed and images were obtained in
clinical utility of an RVT-based strategy to manage patients with a first transverse section only. Lumen compressibility was then evaluated by
episode following idiopathic or provoked DVT of the lower limbs. gentle pressure of the probe. The RVT diameter was taken by measuring
the distance between the anterior and posterior walls of the vein on
freeze-frame B-mode images during compression with the ultrasound
Sergio Siragusa is an Associate Professor of Haematology in the Faculty of Medicine at the
University of Palermo, where he is Head of the Haemostasis and Thrombosis Unit. His
probe.
11
Measurements were taken at the common femoral vein 1cm
research interests include venous thromboembolism, particularly focused on clinical trials on
below the inguinal ligament and the popliteal vein, at the most
anticoagulation. His work is documented in several peer-reviewed articles. He is a member of
prominent crease in the mid-popliteal fossa. RVT was arbitrarily scored as
the most important international societies in the field of haematology. Professor Siragusa has
received seven international awards for his research, including one from the American Society ‘absent’ when the figure was less than or equal to 40% of the vein
of Hematology (ASH).
diameter.
9
A patient was considered as having RVT when a persisting
E:
sergio.siragusa@unipa.it thrombus was shown to be present in at least one of the two examined
vein segments.
52 © TOUCH BRIEFINGS 2008
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