Residual Venous Obstruction Research Articles

Chronic inflammatory diseases increase the risk of post-thrombotic syndrome: A prospective cohort study

BackgroundClinical management of patients with deep vein thrombosis (DVT) is centered around their risk of recurrent venous thromboembolism (VTE) and post-thrombotic syndrome (PTS). While chronic inflammatory disease (CID) has been established as a risk factor of (recurrent) VTE, research about its potential impact on PTS is lacking. ObjectivesWe aimed to assess the risk of PTS in patients with CID, stratifying for the use of anti-inflammatory treatment. Patients/MethodsConsecutive patients with proximal DVT and no active cancer between 2003 and 2018 received a two-year prospective follow-up. CID included inflammatory bowel disease, rheumatic diseases, and gout. Residual venous obstruction (RVO) was assessed by compressive ultrasound after 3–6 months. PTS was diagnosed using the Villalta score after 6–24 months. Hazard ratios (HR) and odds ratios (OR) were adjusted for patient characteristics. The medical ethics committee approved this study. ResultsIn total 82 of 801 patients had CID (10.2 %). PTS more often developed in patients with CID (35.4% vs. 18.9 %, p < 0.001) than in those without CID (HR 1.72 [1.15–2.58]). The prevalence of RVO was similar in patients with and without CID (36.8% vs. 41.4 %), and RVO was strongly associated with PTS in patients with CID (OR 3.21 [1.14–9.03]). Moreover, patients with untreated CID (44 %, n = 36) more often had RVO than those with treated CID (51.6% vs. 26.7 %, p = 0.027), and accordingly had a higher risk of PTS (HR 2.18 [1.04–4.58]). ConclusionsPatients with CID had an increased risk of developing PTS, especially those without anti-inflammatory treatment, possibly due to an unfavorable impact on RVO-related venous pathology.

Residual Venous Obstruction as an Indicator of Clinical Outcomes following Deep Vein Thrombosis: A Management Study.

Residual venous obstruction (RVO) is considered a risk factor of recurrence and possibly other clinical outcomes following deep vein thrombosis (DVT). Current guidelines do not support an RVO-tailored duration of anticoagulant therapy; contemporary data of such management strategies are scarce. We aimed to evaluate an RVO-based management strategy and to assess associations of RVO with recurrence, post-thrombotic syndrome (PTS), arterial events and cancer. To gain further insight, D-dimer levels were measured 1 month after stopping anticoagulant therapy. Consecutive patients with symptomatic, proximal DVT were treated in a 2-year clinical care pathway (CCP) at Maastricht University Medical Center and were followed up to 5 years. RVO was assessed at the end of regular duration of anticoagulant therapy, which was extended once if RVO was detected. The study was approved by the medical ethics committee. From a total of 825 patients, 804 patients (97.5%) completed the CCP and 755 (93.9%) were available for extended follow-up. Most patients (76.5%) stopped anticoagulant therapy. Incidence rates of recurrence, PTS, arterial events, and cancer were 4.4, 11.9, 1.7, and 1.8 per 100 patient-years, respectively. RVO was independently associated with PTS (hazard ratio [HR]: 1.66 [1.19-2.32]) and arterial events (HR: 2.07 [1.18-3.65]), but not with recurrence or cancer. High D-dimer was associated with recurrence (HR: 3.51 [2.24-5.48]). Our RVO-based management strategy might have attenuated the association of RVO with recurrence. In addition, RVO identified patients at increased risk of PTS and arterial events, which might be used to identify patients in need of alternative treatment strategies.

Translational insights into mechanisms underlying residual venous obstruction and the role of factor XI, P-selectin and GPVI in recurrent venous thromboembolism

BackgroundResidual venous obstruction (RVO) after deep vein thrombosis (DVT) is considered a risk factor of recurrent venous thromboembolism (VTE), arterial events and post-thrombotic syndrome (PTS). We hypothesized thrombo-inflammatory markers might be associated with RVO and clinical outcomes. Materials and methodsIn a DVT cohort with routine RVO-assessment and 5-year follow-up, patients were invited for blood withdrawal after stopping anticoagulants. Thrombin generation potential, coagulation enzyme:inhibitor complexes, soluble platelet markers and clinical markers were measured in platelet-poor plasma. Associations were represented as odds ratio (OR) or hazard ratio (HR) per standard deviation. ResultsPatients with RVO (102/306, 33 %) had higher rates of PTS (24 vs. 12 %, p = 0.008), but similar rates of recurrence (16 vs. 15 %, p = 0.91) and arterial events (7 vs. 4 %, p = 0.26). RVO was associated with thrombin peak height (OR 1.40 [1.04–1.88]), endogenous thrombin potential (ETP, OR 1.35 [1.02–1.79]), and CRP (OR 1.74 [1.10–2.75]). Recurrent VTE was associated with ETP (HR 1.36 [1.03–1.81]), FXIa:C1-inhibitor (HR 1.34 [1.04–1.72]), thrombin:antithrombin (HR 1.36 [1.16–1.59]), soluble P-selectin (HR 2.30 [1.69–3.11]), soluble glycoprotein VI (sGPVI, HR 1.30 [1.01–1.69]), D-dimer (HR 1.56 [1.31–1.86]), and factor VIII (HR 1.44 [1.15–1.82]). Arterial events were associated with sGPVI (HR 1.80 [1.25–2.59]). PTS was not associated with any marker. ConclusionsOur findings indicate RVO was associated with thrombo-inflammation, but this did not predict clinical outcomes in this setting. Importantly, we found recurrent VTE was associated with ongoing coagulation and platelet activation in patients well beyond the acute phase of DVT. Furthermore, sGPVI indicated an increased risk of arterial events, highlighting the role of platelets in arterial thrombosis following DVT.

How to optimize the prevention of post‑thrombotic syndrome: recent advances.

Post‑thrombotic syndrome (PTS) is the most frequent complication of deep vein thrombosis, and it can be detrimental to the quality of life of the affected patients. Once affected by this chronic condition, the patient's treatment options are very limited, so preventive therapies are crucial. Currently, the prevention of PTS is hampered by the lack of unequivocally effective therapies. However, improved insight into pathogenesis of this condition acquired in recent years, including the central role of residual venous obstruction, could lead to a better application of existing therapies and identification of novel therapeutic targets. Plausible therapeutic agents include flavonoids and statins, while promising future agents include those that target leukocyte‑endothelial interaction. Moreover, differences in PTS risk were found to be partly explained by a tendency of patients to form clots that are less susceptible to lysis. Finally, identifying patients that are expected to benefit most from certain therapies is equally valuable for the success of future preventive strategies. This requires exploration of better risk stratification through machine learning techniques.

Derin Venöz Tromboz Tanılı Hastaların Kateter Yönlendirmeli Tromboliz tedavisi ile Endovasküler Tedavisi: Erken Dönem ve Birinci Yıl Sonuçları

INTRODUCTION: Deep Vein Thrombosis leads to post thrombotic syndrome in the long term. The risk of developing a post thrombotic syndrome increases when anticoagulation is the only treatment. Catheter-directed thrombolysis methods were developed because of the high bleeding risk of systemic thrombolytic therapy. Along with hybrid approaches Catheter-directed thrombolysis aim to reduce the frequency of post thrombotic syndrome. We retrospectively report the early and follow-up results of our patients in whom we performed Catheter-directed thrombolysis. METHODS: 31 patients(aged 23-87) had been diagnosed with acute proximal Deep Vein Thrombosis(≤15 days’ duration). Catheter-directed thrombolysis and if needed stent implantations were performed successfully. The patients who had a thrombosis of the inferior vena cava also underwent the placement of a vena cava filter. Patients were evaluated at 1, 6 and 12 months. Villalta scores were also determined for the diagnosis of post thrombotic syndrome. RESULTS: 19 had a thrombus in the iliofemoral. The thrombus was extending to the inferior vena cava in six patients. In 12 patients the thrombus was femoropopliteal. The six patients whose thrombus extended to the inferior vena cava, underwent venous filter placement. In five of the iliofemoral-thrombus patients, intraoperative control venography revealed iliac stenosis. This stenosis was treated with iliac stent implantation. Clot-lysis was completely(&gt;90% lysis) in twelve, partially(50-90% lysis) in seven of the 19 iliofemoral-thrombus patients. Ten of the femoropopliteal-thrombus patients achieved a complete and two a partial clot-lysis. There was minor bleeding in two patients. Major bleeding was not reported. DISCUSSION AND CONCLUSION: Catheter-directed thrombolysis reduce the frequency of post thrombotic syndrome. Residual venous obstruction after Catheter-directed thrombolysis should be treated by balloon dilatation/stent implantation to prevent re-thrombosis. We believe that treatment with a hybrid approach may be more effective in protecting patients from post thrombotic syndrome.

The Impact of Electrical Calf Muscle Stimulation on the Residual Venous Obstruction in Patients Finished Standard Anticoagulation

Introduction - Residual venous obstruction (RVO) after deep vein thrombosis (DVT) is one of the important risk factors for recurrent DVT. There is a lack of evidence regarding the natural history of RVO and potentiality for full vein recanalization. The aim of the study was to assess the efficacy of electrical calf muscle stimulation (EMS) in patients with post-thrombotic syndrome (PTS) and residual venous obstruction after cessation of a standard anticoagulation.

Presence and degree of residual venous obstruction on serial duplex imaging is associated with increased risk of recurrence and progression of infrainguinal lower extremity deep venous thrombosis

ObjectiveThe role of follow-up venous duplex ultrasound (DUS) after acute lower extremity deep vein thrombosis (DVT) remains unclear, yet it is commonly performed. We aimed to clarify the role of follow-up DUS. Our primary objective was to determine the association between the presence of residual venous obstruction (RVO) on DUS and DVT recurrence or propagation (rDVT). Secondary objectives included finding risk factors associated with RVO and rDVT. MethodsWe conducted a retrospective study of patients diagnosed with DVT on DUS from January 1, 2011, to December 31, 2013, that received a follow-up DUS. Patient demographics, risk factors, medications, and DUS findings were recorded. Ten segments from the common femoral to distal calf veins were checked for the presence of RVO, DVT propagation, and recurrence. RVO was defined as any nonacute venous obstruction with more than 40% of luminal diameter remaining during compression or the presence of chronic post-thrombotic occlusive disease. rDVT was measured as either a new acute DVT in the previously involved segment, or involvement of a new segment in the same extremity. ResultsA total of 185 lower extremities representing 156 patients met the inclusion criteria. RVO was noted in 61.1% of limbs. The 3-year rDVT rate was 10.3%. Patients with recurrent venous thromboembolism or thrombophilia had a higher risk of developing RVO (odds ratio [OR], 2.89, P < .01; OR, 4.39, P = .04, respectively). Extremities with larger clot burden had an increased risk of RVO on follow-up DUS (OR, 1.25 per segment; P < .01). The presence and degree of RVO on follow-up DUS had an increased risk of rDVT on subsequent DUS (OR, 3.90, P = .04; OR, 1.21 per segment, P = .04, respectively). Limbs with complete resolution of DVT by DUS had a significantly decreased risk of rDVT (OR, 0.26; P = .04). ConclusionsExtremities with larger initial clot burden exhibited an increased risk of subsequent RVO. The presence of RVO and, interestingly, the number of involved segments on follow-up DUS increased the risk of rDVT. Our results suggest that the presence of residual disease and increased RVO burden on follow-up DUS after an acute DVT may identify those patients who are at an increased risk for rDVT and may help guide the duration of anticoagulation therapy.

Initial and Long-Term Treatment of Pulmonary Embolism: Current Approach and Future Perspectives.

Pulmonary embolism is associated with variable risk of early mortality, ranging from less than 1% to more than 15%. Risk stratification, based on clinical variables and signs of right ventricular dysfunction, is crucial to decide the best management and treatment strategy. Home therapy may be an option for low-risk patients, whereas patients at intermediate risk need to be hospitalized and some of them, at intermediate high risk, may require more intensive monitoring to early detect signs of haemodynamic decompensation. The initial treatment is based on anticoagulants with rapid onset of action, either parenteral (heparin/fondaparinux) or oral (direct oral anticoagulants, DOACs). Thereafter, DOACs (or, if contraindicated, vitamin K antagonists) needs to be continued for at least 3 months. Beyond this period, an individual re-evaluation of the risk-to-benefit ratio of anticoagulation should be performed, based on several factors, including the type of index event, age, sex, D-dimer and residual venous obstruction. Possibly safer strategies can be offered to higher risk patients requiring extended duration of treatment, including the DOACs apixaban and rivaroxaban at reduced dose.

Chronic iliofemoral vein obstruction – an under-recognized cause of exercise limitation

Local symptoms of chronic venous insufficiency after deep vein thrombosis (DVT) are well described, but little is known about the effect of residual venous obstruction on exercise capacity. We tested our hypothesis that chronic residual iliofemoral vein occlusion (IFVO) after DVT may impair exercise capacity. Nine post-DVT patients with residual IFVO and effort intolerance were studied; a comparison cohort consisted of 11 healthy volunteers. Exercise tolerance was assessed by bimodality incremental symptom-limited cardiopulmonary testing, using leg and arm ergometers. In healthy subjects, leg vein obstruction was modelled by application to the thighs of cuff tourniquets inflated to 30–40 mmHg. Leg exercise tolerance as measured by oxygen uptake at peak exercise (peak ⩒’O2) was reduced in patients (median 50% predicted (range 36–83%) vs. 88% predicted (67–129%) in normal subjects, p < 0.001). Arm exercise tolerance was also reduced in patients, but less severely than in the legs – the median arm: leg ratio of peak ⩒’O2 was 0.95 (0.77–1.43) in patients vs. a normal ratio of 0.73 (0.6–1.0) in healthy subjects (p < 0.003). In healthy subjects, bilateral leg vein obstruction by tourniquets reduced peak ⩒’O2 in leg exercise to 76% predicted (range 55–108%; p < 0.001 vs. standard test). In conclusion, the comparison of arm vs. leg exercise capacity in post-DVT patients with residual IFVO and the effect of experimental venous obstruction (thigh tourniquets) in healthy subjects suggest that reduced exercise capacity in patients was at least partially caused by reduced venous return. Chronic venous obstruction should be recognized as a cause of exercise limitation.

Risk factors for recurrence in deep vein thrombosis patients following a tailored anticoagulant treatment incorporating residual vein obstruction

BackgroundFinding the optimal duration of anticoagulant treatment following an acute event of deep vein thrombosis (DVT) is challenging. Residual venous obstruction (RVO) has been identified as a risk factor for recurrence, but data on management strategies incorporating the presence of RVO and associated recurrence rates in defined clinical care pathways (CCP) are lacking. ObjectivesWe aimed to investigate the long‐term clinical outcomes and predictors of venous thromboembolism (VTE) recurrence in a contemporary cohort of patients with proximal DVT and managed in a CCP incorporating the presence of RVO. PatientsAll patients treated at the Maastricht University Medical Center within an established clinical care pathway from June 2003 through June 2013 were prospectively followed for up to 11 years in a prospective management study. ResultsOf 479 patients diagnosed with proximal DVT, 474 completed the two‐year CCP (99%), and 457 (94.7%) the extended follow‐up (2231.2 patient‐years; median follow‐up 4.6 years). Overall VTE recurrence was 2.9 per 100 patient‐years, 1.3 if provoked by surgery, 2.1 if a non‐surgical transient risk factor was present and 4.0 if unprovoked. Predictors of recurrent events were unprovoked VTE (adjusted hazard ratio [HR] 4.6; 95% CI 1.7, 11.9), elevated D‐dimer one month after treatment was stopped (HR 3.3; 1.8, 6.1), male sex (HR 2.8; 1.5, 5.1), high factor VIII (HR 2.2; 1.2, 4.0) and use of contraceptives (HR 0.1; 0.0, 0.9). ConclusionsPatients with DVT managed within an established clinical care pathway incorporating the presence of RVO had relatively low incidences of VTE recurrence.

The Impact of Electrical Calf Muscle Stimulation on the Residual Venous Obstruction and DVT Recurrence after Cessation of Standard Anticoagulation

Aim. To assess the efficacy of electrical calf muscle stimulation (EMS) in patients with post-thrombotic syndrome (PTS) and residual venous obstruction (RVO) after cessation of a standard anticoagulation.Methods. This was a prospective comparative clinical trial with masked outcome assessor involving patients after the first episode of unprovoked femoro-popliteal DVT who have completed a standard 6-month course of anticoagulation and had signs of RVO in the affected veins and Villalta score of 5 and more.Totally were enrolled 60 patients in the age of 40-86 years (mean - 58,5 ± 11,4), 38 men and 22 women, divided into two groups of 30 participants. In both groups (main and control) PTS was treated by active walking (at least 5,000 steps per day controlled by an individual pedometer), below-knee graduated compression stockings (23-32 mm Hg) and micronized purified flavonoid fraction (2-month course twice a year). In the main group, EMS with «Veinoplus VI» device (3 procedures of 30 minutes every day) also was used. The main endpoint of the study was symptomatic or asymptomatic recurrent venous thrombosis confirmed by duplex ultrasound (DUS). The additional criteria of treatment efficacy were changes in the degree of current venous stenosis. The patients were followed up for 12 months with monthly DUS, aimed to reveal recurrent DVT, and 6-monthly DUS with evaluation of stenosis degree.Results. RVO was represented by an average of 48%-stenosis of the common femoral vein in 12 patients, 53%-stenosis of the superficial femoral vein in 16 cases and 55%-stenosis of the popliteal vein in all participants. Through 12-month follow up the degree of stenosis decreased in all affected veins in both groups (p<0,05). The most vivid dynamics was found in the popliteal vein: 60.8% - 55.1% - 28.8% in the main group and 50.9% - 30.1% - 27.3% in the control group (p<0,0001) with significant differences between the groups (p=0.004)Recurrence of venous thrombosis was found in 7 of 30 patients in the control group and in 0 of 30 patients in the main group (23.3% vs 0%, p=0.011). In 5 cases the recurrent DVT was silent and revealed by regular DUS and only in 2 cases it had a clinical manifestation. 4 of 5 silent cases were presented with re-occlusion of the early affected vein.Conclusions. There is an ongoing process of deep veins recanalization during 12 months after cessation of anticoagulation in patients with RVO and PTS. Using of EMS in complex treatment of PTS allows to reduce the rate of recurrent DVT and increase the speed of recanalization. DisclosuresLobastov:“Gemakor Labs” Ltd: Honoraria, Research Funding; “BEHO+” Ltd: Honoraria, Research Funding. Ryzhkin:“BEHO+” Ltd: Research Funding. Laberko:“Gemakor Labs” Ltd: Honoraria, Research Funding; “BEHO+” Ltd: Honoraria. Rodoman:“Gemakor Labs” Ltd: Research Funding.

Epidemiology of the post-thrombotic syndrome

The post thrombotic syndrome (PTS) refers to clinical manifestations of chronic venous insufficiency (CVI) following a deep-vein thrombosis (DVT). PTS is the most frequent complication of DVT, which develops in 20 to 50% of cases after proximal DVT and is severe in 5–10% of cases. The reported prevalence of PTS differs widely among studies because of differences in study populations, tools used to assess PTS, and time interval between acute DVT and PTS assessment. The two most important predictors of PTS are extensive proximal character of DVT and previous ipsilateral DVT. Other reported risk factors include pre-existing CVI, obesity, quality of anticoagulant treatment, older age and residual venous obstruction. Standardization of PTS assessment tools combined with the development of patient self-reported PTS scales are likely to constitute a breakthrough in research of the epidemiology of PTS, by allowing comparison between studies, meta-analyses and increasing the feasibility of longer follow-up of DVT patients. This should enable identification of patient populations at high risk of severe PTS, new predictors of PTS and targets for potential new treatments. In this perspective, identification of biomarkers that are predictive of PTS such as markers of inflammation is crucial in ongoing research.

Ultrasound‐assisted versus conventional catheter‐directed thrombolysis for acute iliofemoral deep vein thrombosis: 1‐year follow‐up data of a randomized‐controlled trial

Background In patients with acute iliofemoral deep vein thrombosis (IFDVT), catheter-directed thrombolysis (CDT) aims to prevent the postthrombotic syndrome (PTS). Adding intravascular high-frequency, low-power ultrasound energy to CDT does not seem to improve the immediate thrombolysis results but its impact on clinical outcomes at 12 months is not known. Patients/Methods In this randomized-controlled trial, 48 patients (mean age 50 ± 21 years; 52% women) with acute IFDVT were randomized to conventional CDT (n = 24) or ultrasound-assisted CDT (USAT; n = 24). In both groups, a fixed-dose thrombolysis regimen (20 mg r-tPA over 15 h) was used, followed by routine stenting of residual venous obstruction. At 12 months, PTS and venous disease severity (Villalta score and revised Venous Clinical Severity Score [rVCSS]), disease-specific quality of live (QOL; CIVIQ-20) and duplex-sonographic outcomes were assessed. Results Among the 45 surviving patients, 40 (89%; 95% confidence interval [CI] 76-96%) patients were free from PTS (defined as Villalta score < 5 points; 83%, 95% CI 61-95% in the USAT and 96%, 95% CI 77-100% in the CDT group), with a similar mean total Villalta score of 2.3 ± 2.9 vs. 1.7 ± 1.6, and a mean total rVCSS of 3.0 ± 3.5 vs. 2.7 ± 2.9 in the USAT and the CDT groups, respectively. Both groups had good disease-specific QOL with a CIVIQ-20 score of 29.4 ± 11.8 vs. 26.1 ± 7.8, respectively. Primary (100% vs. 92%) and secondary (100% vs. 96%) iliofemoral patency rates and presence of femoro-popliteal venous reflux (39% vs. 33%) were similar in both groups. Conclusion The addition of intravascular ultrasound energy to conventional CDT for the treatment of acute IFDVT did not have any impact on relevant clinical or duplex sonographic outcomes, which were favorable in both study groups. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier:NCT01482273.

Preliminary Investigations Showing Venous Thromboembolism Recurrence in Patients with Residual Venous Obstruction in Singaporean Population.

This study aims to determine the association of residual venous obstruction (RVO) with recurrent venous thromboembolism (VTE). A retrospective cohort study was conducted determining if RVO on ultrasonography is associated with recurrent VTE in a Singaporean population. The subjects were identified from the Vascular Diagnostic Laboratory patients' record of Tan Tock Seng Hospital (TTSH), Singapore between 2008 and 2013. All the patients included had RVO after 3 months of anticoagulation. Data such as age, gender, race, thrombus location, etiology, history of malignancy, thrombophilia screen, treatment duration, and follow-up were recorded for analysis. Statistical analysis was performed using Stata/SE 13.1 (StataCorp LLC). The study was approved by the National Healthcare Group Domain Specific Review Board (DSRB), Singapore. Out of the 34 patients who had RVO, 6 (17.6%) developed VTE recurrence. Patients were treated with anticoagulation for a mean time of 24.5 months. The mean follow-up time for VTE recurrence was 25.4 months. Out of the six patients who had VTE recurrence, one had common iliac vein involvement, four had superficial femoral vein and common femoral vein involvement, zero had popliteal vein involvement, and one had calf veins involvement. There was a significant association between thrombophilia ( p = 0.0195) and malignancy ( p = 0.020) at inclusion with the risk of recurrent VTE. The presence of RVO after 3 months of anticoagulation is likely to increase the risk of VTE recurrence. Larger studies with RVO are needed to evaluate if there is an increased risk of VTE recurrence in the Asian population.

VESS26. Presence and Degree of Residual Venous Obstruction on Serial Duplex Imaging Increases the Risk of Recurrence and Progression of Lower Extremity Deep Venous Thrombosis

VESS26. Presence and Degree of Residual Venous Obstruction on Serial Duplex Imaging Increases the Risk of Recurrence and Progression of Lower Extremity Deep Venous Thrombosis

Dynamics of Residual Venous Obstruction after Electrical Stimulation of Crural Muscles following the Completion of the Standard Course of Anticoagulation Therapy in Patients with Postthrombotic Syndrome: the Results of the Comparative Non-Randomized Study

Dynamics of Residual Venous Obstruction after Electrical Stimulation of Crural Muscles following the Completion of the Standard Course of Anticoagulation Therapy in Patients with Postthrombotic Syndrome: the Results of the Comparative Non-Randomized Study

Predictors of the post-thrombotic syndrome and their effect on the therapeutic management of deep vein thrombosis.

The post-thrombotic syndrome (PTS), which refers to chronic clinical manifestations of venous insufficiency after a deep vein thrombosis (DVT), is a frequent occurrence. Because treatment options for PTS are limited, its management mainly relies on the prevention of its occurrence after DVT. Among identified predictors of PTS, extensive proximal location of DVT directly modifies the treatment of DVT because of the possibility of performance of complementary endovascular techniques. The association between poor international normalized ratio control and subsequent PTS should encourage physicians to perform frequent and regular international normalized ratio monitoring of patients receiving vitamin K antagonists. Other identified PTS risk factors are ipsilateral DVT recurrence, older age, pre-existing primary venous insufficiency, obesity, and residual venous obstruction, but these are less amenable to therapy. Because of their potential therapeutic implications, identification of biomarkers that are predictive of PTS such as markers of inflammation is crucial and such research is ongoing.

Predicting the risk of recurrent venous thromboembolism (VTE).

To optimize patient outcomes with anticoagulation for venous thromboembolism (VTE), it is essential to assess patients for their recurrence risk. In this article, I will review the impact of clinical and laboratory risk factors for recurrent VTE. The presence or absence of VTE risk factors at the time of the index thrombotic event provides important information regarding recurrence risk. Patients with potent situational risk factors for thrombosis (e.g., surgery) are at low risk for recurrence while patients suffering unprovoked events are at high risk for recurrence. The presence of non-surgical clinical risk factors place patients at intermediate recurrence risk. Other clinical risk factors of variable recurrence potential include age, sex, cancer, pregnancy/puerperium, hormonal therapy and obesity. Laboratory risk factors for recurrence include thrombophilia, D dimer and other global coagulation assays as well as residual venous obstruction. Several multivariate VTE risk assessment models have been developed that combine clinical and laboratory risk factors of recurrence. If validated, these risk scores may allow for personalized anticoagulation therapy tailored to patients' individual recurrence risk.

Outcome of venous stenting following catheter directed thrombolysis for acute proximal lower limb venous thrombosis: a prospective study with venous Doppler follow-up at 1-year.

Functional outcome of venous stent placement for the management of acute iliofemoral deep vein thrombosis (DVT) following catheter-directed thrombolysis (CDT), remain undefined. The purpose of this study was to assess immediate and intermediate term outcomes among patients treated with venous stenting following CDT in patients with proximal lower limb DVT. Thirty consecutive patients aged between 20-70years with proximal lower limb DVT formed the study group. The mean duration of CDT done with streptokinase was 4.5±1.3days. Patients with residual venous obstruction and/or large clot burden were treated further with venous angioplasty and/or stenting. Primary endpoint was to evaluate the safety, efficacy and patency of venous stenting in the management of incomplete result following CDT. After 12months, post-thrombotic syndrome (PTS) was assessed clinically using Villalta scale and deep venous patency was assessed through duplex ultrasound. We studied 8 (5 female and 3 male) patients with 9 (3 left and 6 right) limb involvement and 13 stent (4 balloon expandable and 9 self expandable) placement. All patients improved clinically immediately following venous stenting. Technical success was achieved in all patients. One patient developed pulmonary embolism during course of hospital stay. One patient had stent thrombosis and PTS and another patient died due to carcinoma breast during follow-up. Deep venous stenting is an effective mode of treatment in proximal acute lower limb DVT with high late patency rate up to 1-year.

Duplex imaging of residual venous obstruction to guide duration of therapy for lower extremity deep venous thrombosis.

Clinical trials have shown that the presence of ultrasound-identified residual venous obstruction (RVO) on follow-up scanning may be associated with an elevated risk for recurrence, thus providing a potential tool to help determine the optimal duration of anticoagulant therapy. We performed a systematic review to evaluate the clinical utility of post-treatment duplex imaging in predicting venous thromboembolism (VTE) recurrence and in adjusting duration of anticoagulation. The Ovid MEDLINE Database, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Database of Abstracts of Reviews of Effects were queried for the terms residual thrombus or obstruction, duration of therapy, deep vein thrombosis, deep venous thrombosis, DVT, venous thromboembolism, VTE, antithrombotic therapy, and anticoagulation, and 228 studies were selected for review. Six studies determined the rate of VTE recurrence on the basis of the presence or absence of RVO. Findings on venous ultrasound scans frequently remained abnormal in 38% to 80% of patients, despite at least 3 months of therapeutic anticoagulation. In evaluating for VTE recurrence, the definition of RVO varied widely in the literature. Some studies have shown an association between RVO and VTE recurrence, whereas other studies have not. Overall, the presence of RVO is a mild risk factor for recurrence (odds ratio, 1.3-2.0), but only when surveillance imaging is performed soon after the index deep venous thrombosis (3 months). RVO is a mild risk factor for VTE recurrence. The presence or absence of ultrasound-identified RVO has a limited role in guiding the duration of therapeutic anticoagulation. Further research is needed to evaluate its utility relative to other known risk factors for VTE recurrence.