Percutaneous Transcatheter Treatment of Deep Venous Thrombosis

Percutaneous transcatheter treatment of patients with deep venous thrombosis (DVT) consists of thrombus removal with catheter-directed thrombolysis, mechanical thrombectomy, angioplasty, and/or stenting of venous obstructions. In some cases, patients may also be given pulmonary embolism (PE) prophylaxis by means of filter placement in the inferior vena cava.

The goals of endovascular therapy include reducing the severity and duration of lower-extremity symptoms, preventing PE, diminishing the risk of recurrent venous thrombosis, and preventing postthrombotic syndrome (PTS).

The decision whether to use percutaneous transcatheter treatment and, if so, which technique to choose, is complicated by the lack of data from multicenter prospective randomized trials regarding the safety and efficacy of these therapies. Problems in the existing literature are variability in patient selection and the lack of standard definitions of short-term or long-term efficacy and complications. Nevertheless, a consensus regarding indications exists, although it is based on midlevel evidence from nonrandomized, controlled trials.

When an invasive procedure is considered, the benefit must be weighed against the added risk compared with standard anticoagulant therapy. If it is to be performed, the intervention must improve the results of current medical therapy. With heparin therapy, the risk of PE is 2%, the risk of recurrent DVT is 4%, and the risk of major bleeding is 5%.

More difficult to determine is the risk of PTS, which develops within 2 years in approximately one quarter of patients with symptomatic DVT and one half of those with proximal DVT. ^{[1, 2, 3]}

For more information, see Deep Venous Thrombosis.

Catheter-directed thrombolysis involves the acceleration of the body’s natural thrombolytic pathway. The basic mechanism of action is the activation of fibrin-bound plasminogen, which promotes thrombus resolution. ^[4]

Observational studies from the University of Washington demonstrated that early lysis resulted in preserved valve function, whereas persistent thrombus resulted in the most severe forms of postthrombotic morbidity. ^[5]

Direct intrathrombus injection of the thrombolytic agent protects the medication from deactivation by circulating inhibitors and achieves higher drug concentration at the site of thrombosis with a lower total dose than would be used for systemic intravenous thrombolytic therapy. The lower circulating drug levels are the suggested mechanism for the lower incidence of systemic and, in particular, intracranial hemorrhagic complications reported with catheter-directed thrombolysis.

Thrombolytic therapy offers significant advantages over conventional anticoagulant therapy, including the prompt resolution of symptoms, the prevention of pulmonary embolism, the restoration of normal venous circulation, the preservation of venous valvular function, and the prevention of postthrombotic syndrome. However, thrombolytic therapy does not prevent clot propagation, rethrombosis, or subsequent embolization. Heparin therapy and oral anticoagulant therapy must always follow a course of thrombolysis.

Success rates with catheter-directed thrombolytics vary depending on the age of the thrombus and its proximity to the inferior vena cava. Success with thrombolytic use in acute iliofemoral venous thrombosis has been reported to be 80-85%, with 1-year patency at 60-65%. Major bleeding complication rates vary from 5% to 11%; most bleeding occurs at the puncture site. ^{[6, 7]}

A prospective registry of 287 patients treated with a mean 53-hour infusion of urokinase-type plasminogen activator (uPA) showed anatomic success in 83%. ^[7] About 34% of patients received adjunctive stent placement for underlying lesions. Major bleeding and rethrombosis were observed in 11% and 25% of patients, respectively, at 30-day follow-up. ^[7]

Three studies demonstrated improved long-term venous function after catheter-directed thrombolysis versus anticoagulation alone. Two showed a decrease in reflux or symptoms from 41-70% to 11-22%. In a retrospective case-control study, quality-of-life scores (including stigmata, health distress, physical function, and symptoms) were superior at 22-month follow-up after catheter-directed thrombolysis with anticoagulation than after anticoagulation alone. ^[8]

The transcatheter approach facilitates the diagnosis of predisposing anatomic lesions or anomalies. In patients with iliofemoral deep venous thrombosis, catheter-directed thrombolysis was successful for recanalization in 92-100% of patients, and it revealed an underlying lesion in 50-66%. Treatment of these stenoses with angioplasty and stent placement reestablished unobstructed flow and achieved a prompt clinical response. ^{[6, 7, 9]} Studies with 2-year follow-up documented a 5-11% incidence of valvular incompetence.

Indications for intervention include the relatively rare phlegmasia or symptomatic inferior vena cava thrombosis that responds poorly to anticoagulation alone, or symptomatic iliofemoral or femoropopliteal deep venous thrombosis (DVT) in patients with a low risk of bleeding. In the last groups, the goal is to reduce the high risk of postthrombotic syndrome (PTS) or to achieve symptomatic relief in conjunction with angioplasty or stent placement.

Phlegmasia cerulea dolens treatment

Phlegmasia cerulea dolens is an indication for emergency catheter-directed thrombolysis in patients with moderate or low bleeding risks. ^[10] This recommendation is based on reports of limb salvage, which stand in contrast to the high rates of limb amputation and death seen with standard therapies. ^[11] Surgical thrombectomy remains an effective option in patients at high risk for hemorrhagic complications, although it often results in incomplete thrombus removal, recurrent DVT, and an increased incidence of systemic complications.

Inferior vena cava thrombosis treatment

Acute or subacute inferior vena cava thrombosis that causes at least moderate pelvic congestion, limb symptoms, or compromised visceral venous drainage warrants catheter-directed thrombolysis. Involvement of the suprarenal cava, renal veins, and/or hepatic veins may precipitate acute renal or hepatic failure. Thrombus that involves the upper inferior vena cava may make it impossible to place an inferior vena cava filter for pulmonary embolism (PE) prophylaxis.

Subacute and chronic Iliofemoral DVT treatment

Subacute and chronic iliofemoral DVT is accompanied by moderate to severe pelvic or limb symptoms with a low bleeding risk. Because recanalization of the iliac vein is unlikely, iliofemoral DVT often produces valvular reflux.

This combination of outflow obstruction and reflux is associated with the most symptomatic forms of PTS. In this situation, patients have venous damage, and the alternative is venous bypass. In these settings, catheter-directed thrombolysis is seldom expected to completely clear the vein, but it is often used to remove any acute component of thrombus and to uncover chronic stenoses or an underlying anatomic abnormality as an adjunct to angioplasty or stent placement. Compared with systemic thrombolysis, catheter-directed thrombolysis improves the preservation of valve competence (44% vs 13%).

Acute iliofemoral or femoropopliteal DVT treatment

Whether catheter-directed thrombolysis is indicated in the relatively common event of acute iliofemoral or femoropopliteal DVT is somewhat controversial. Catheter-directed thrombolysis may be superior to anticoagulation with regard to decreasing the incidence of recurrent DVT and PTS. However, the evidence is not conclusive.

Catheter-directed thrombolysis improves thrombus clearance compared with systemic thrombolysis. Few DVT cases resolve after heparin therapy, but systemic thrombolysis improves the rate to 30%, and catheter-directed thrombolysis removes 80% of thrombi. ^[12] Reports of catheter-directed thrombolysis for the management of acute DVT between 1994 and 2004 described anatomic and clinical success rates of 76-100%. The incidence of major hemorrhagic complications was 0-24%.

The literature shows that treatment of iliofemoral DVT with catheter-directed thrombolysis reduced occurrence of PTS (6.6% of patients undergoing treatment developed PTS vs 14% in the control group). ^[13] Major bleeding episodes had no significant difference between the treatment and control groups. Another study demonstrated that both major and minor bleeding episodes were limited to local bleeding periprocedurally. ^[14]

Asymptomatic DVT

Asymptomatic DVT is not considered an indication for endovascular intervention at this time. The incidence of PTS at 5 years after asymptomatic calf or proximal DVT is low, at 5%. ^[15] The absence of symptoms may reflect the lack of the obstructive effect that is proposed to initiate the syndrome. However, while the incidence of PTS may not warrant endovascular treatment, some reports suggest that treatment of asymptomatic DVT may be necessary to prevent most cases of PE that are diagnosed at autopsy. Patients with asymptomatic proximal DVT had a 13.7% risk of mortality risk versus a 2% mortality risk in patients without DVT at all. That is, asymptomatic proximal DVT is associated with a higher all-cause mortality than no venous thromboembolism. ^[16]

Guidelines recommendations

The American College of Chest Physicians (ACCP), ^{[17, 18, 19]} American Heart Association (AHA), ^[20] and Society of Interventional Radiology (SIR) ^{[21, 22]} all recommend the use of use of catheter-directed thrombolysis in patients with iliofemoral DVT, as well as emergency conditions including phlegmasia cerulea dolens. ^{[23, 24]}  Contraindications to the use of catheter-directed thrombolysis include active internal bleeding along with recent (< 3 month) history of stroke, neurosurgery for intracranial bleed, or trauma. ^[24]  Indications for catheter-directed thrombolysis in patients with iliofemoral DVT include acute onset of thrombus less than 21 days; severe symptoms from increased DVT burden such as edema, paresthesias, pain, claudication, and ulceration; and failure of conservative therapy with anticoagulation alone. ^[25]

The AHA published its own extensive guide to management of iliofemoral DVT (as well as sections on pulmonary embolism and thromboembolic pulmonary hypertension). ^[20] They recommend that patients receive catheter-directed thrombolysis with acute limb-threatening compromise (such as phlegmasia cerulea dolens), and worsening symptoms, and/or rapid thrombus extension from iliofemoral DVT despite anticoagulation. Additional recommendations include that catheter-directed thrombolysis is a reasonable first-line treatment in patients with acute iliofemoral DVT to reduce risk of PTS in patients with low perioperative bleeding risk. ^[20]

Contraindications for percutaneous transcatheter treatment of deep venous thrombosis (DVT) are the same as those for thrombolysis in general. Absolute contraindications include active internal bleeding or disseminated intravascular coagulation, a cerebrovascular event, trauma, and neurosurgery within 3 months.

Relative contraindications include major surgery within 10 days, obstetric delivery, major trauma, organ biopsy, intracranial or spinal cord tumor, uncontrolled hypertension, major gastrointestinal hemorrhage (within 3 months), serious allergic reaction to a thrombolytic agent, known right-to-left cardiac or pulmonary shunt or left-heart thrombus, and an infected venous thrombus. Unfortunately, most patients with DVT have absolute contraindications to thrombolytic therapy.

Thrombolytic therapy is also not effective once the thrombus is adherent and begins to organize. Venous thrombi in the legs are often large and associated with complete venous occlusion. In these cases, thrombolytic agents act on the surface of the clot but may not be able to penetrate and lyse the entire thrombus.

Data from many published studies indicate that thrombolytic therapy is more effective than heparin in achieving vein patency. The unproven assumption is that the degree of lysis observed on posttreatment venography is predictive of future venous valvular insufficiency and late (5-10 y) development of postthrombotic syndrome (PTS). Preliminary evidence suggests that thrombolytic therapy reduces but unfortunately does not entirely eliminate the incidence of PTS at 3 years.

The hemorrhagic complications of thrombolytic therapy are formidable (approximately 3 times higher than that of anticoagulant therapy) and include the small, but potentially fatal, risk of intracerebral hemorrhage. The uncertainty regarding thrombolytic therapy is likely to continue.

The American College of Chest Physicians (ACCP) 2008 consensus guidelines recommend catheter-directed thrombolytic therapy only for selected patients with extensive acute proximal deep venous thrombosis (DVT) (eg, those with iliofemoral DVT, symptoms for < 14 days, good functional status, and life expectancy of >1 year) who are at low risk of bleeding. ^[17]  In 2016, the ACCP recommendatios included the following ^[18] :

• Suggested use of anticoagulant therapy alone over catheter-directed thrombolysis in those with acute proximal DVT of the leg
• Suggested systemic thrombolytic therapy using a peripheral vein over catheter-directed thrombolysis in the setting of acute pulmonary embolism (PE) treated with a thrombolytic agent
• Suggested catheter-directed thrombolysis if appropriate expertise and resources are available over no such intervention in the setting of acute PE associated with hypotension and (i) a high bleeding risk, (ii) failed systemic thrombolysis, or (iii) shock that is likely to cause death before systemic thrombolysis can take effect (eg, within hours)

Treatment of DVTs can sometimes include a combined mechanical and catheter-directed thrombolysis in modern settings; however, this specific technique is not currently recommended by US institutions due to lack of evidence on the use of both techniques concurrently. ^[26]

Access to the iliofemoral venous circulation is usually obtained via the popliteal vein, using ultrasonographic guidance, although the common femoral, tibial, or internal jugular veins are also used. When thrombolysis is planned, use of ultrasonography and a micropuncture 21-gauge needle are recommended to minimize bleeding risk. ^[27]

Diagnostic venography is used to identify the extent of deep venous thrombosus (DVT). Fluoroscopic guidance is the most accurate and straightforward means of placing infusion catheters or devices. A sheath is placed, and a multiple–side-hole catheter or wire is used to maximize delivery of the thrombolytic agent to the surface area of the thrombus.

During thrombolysis, patients remain on bed rest, with frequent monitoring of their vital signs and puncture sites. Pericatheter oozing, enlarging hematoma, or evidence of gastrointestinal or genitourinary bleeding warrant immediate attention. Additional punctures, particularly arterial or intramuscular ones, should be avoided.

A separate intravenous access facilitates blood sampling, which is performed at 6-hour intervals to monitor the patient’s hematocrit; platelet count; activated partial thromboplastin time (aPTT), if concomitant heparinization is used; and, possibly, fibrinogen values. Monitoring of fibrinogen levels is controversial, although levels below 4.4 µmol/L (150 mg/dL) might indicate a clinically significant systemic effect.

Comparison of plasminogen activators and dosages

Plasminogen activators include streptokinase, urokinase-type plasminogen activator (uPA), tissue-type plasminogen activator (tPA; alteplase), tenecteplase (TNK), and recombinant tPA (r-tPA; reteplase). The US Food and Drug Administration (FDA) has approved only streptokinase for systemic thrombolytic therapy of DVT. However, this agent is not currently recommended because of high rates of allergic reaction and bleeding complications and because of the availability of lower-risk agents. In the 1980s and 1990s, uPA was used extensively, but when it was temporarily taken off the market, tPA and r-tPA subsequently became the agents of choice.

In a retrospective analysis of catheter-directed thrombolysis for DVT, no significant differences were observed between uPA, tPA, and r-tPA with regard to success rate (>97%) or major complications (3-8%), although tPA and r-tPA were significantly less expensive than uPA. ^[28]

Recommended continuous dosages for catheter-directed thrombolysis of unilateral leg DVT are as follows:

• tPA: 0.5-1.0 mg/h

• r-tPA: 0.25-0.75 U/h

• TNK: 0.25-0.5 mg/h

Other dosing options include an initial lacing dose, which entails an initial bolus given throughout the target thrombus, and a front-loaded dose, which is a high concentration given for the first few hours. No advantage to either approach has been demonstrated.

Concomitant heparinization

Most practitioners use concomitant heparinization. Previously, full heparinization was commonly used in conjunction with uPA, whereas the current trend is to administer subtherapeutic heparin with tPA. Low-molecular-weight heparin (LMWH) has not been studied in this setting.

In the coronary literature, use of enoxaparin improved outcomes (death and myocardial infarction reduced from 12% to 9.9%), but it significantly increased bleeding complications (from 1.4% to 2.1%).

The Society of Interventional Radiology (SIR) published a position paper supporting the adjunctive use of catheter-directed thrombolysis (CDT) in addition to anticoagulant therapy for carefully selected patients with acute iliofemoral deep venous thrombosis (DVT). ^[21] The authors evaluated this therapeutic option in the context of the major therapeutic goals for the treatment of DVT: (1) provision of early symptom relief, (2) prevention of postthrombotic syndrome (PTS), and (3) prevention of pulmonary embolism (PE).

The position statement cites a number of comparative studies that support the use of CDT to prevent PTS and provide rapid symptom relief. The authors explain that the natural history of iliofemoral DVT is different than that of isolated femoropopliteal DVT. ^[21] In the latter group, recanalization and collateral venous blood flow limit the degree of PTS. However, in the iliac veins, adequate recanalization is unlikely and collateral venous blood flow is minimal. This leads to persistent venous outflow obstruction and an increased risk of PTS.

Long-term studies of patients with iliofemoral DVT reported a 44% incidence of venous claudication at 5-year follow-up with standard anticoagulant therapy alone. Furthermore, the rate of recurrence of DVT is twice as high in patients with an iliofemoral DVT than in those with more distal, femoropopliteal DVT. The authors referenced a meta-analysis that demonstrated a 90% success rate with CDT for thrombus removal, as well as a case-control study that reported a decreased incidence of PTS compared with anticoagulant therapy alone. ^[21]

The SIR recognized that the main risk of adjunctive CDT is bleeding. Their pooled review of 19 published studies reported an 8% incidence of major bleeding (mostly at the catheter insertion site) and an intracranial bleeding rate of only 0.2%, which is less than that reported for systemic thrombolytic therapy. ^[21] However, the range of major bleeding risk in the studies reviewed was actually 0-24%. The incidence of PE was 1%, which is also less than the incidence of PE complicating standard anticoagulant therapy.

However, the authors conceded that no prospective, randomized study has yet been conducted to compare CDT with standard anticoagulant therapy for iliofemoral DVT. In conclusion, the SIR affirmed that the available evidence defended a clinical benefit of CDT in the specific subgroup of patients with iliofemoral DVT, limb-threatening disease, and low bleeding risk. ^[21]

In the CaVenT study, CDT was effective at achieving greater than 50% lysis of DVTs on over 77% of attempts, ^[29] with many relatively recent studies achieving closer to 100% effectiveness as techniques have improved. ^[30] The CaVenT study demonstrated decreased risk in PTS at 24 months post CDT (41.1% vs 55.6% in the control group). ^[29]  The study also demonstrated reduced risk of recurrent DVT and increased patency of the iliofemoral vein 6 months post CDT.

Measurement of outcomes from use of CDT has focused on development of PTS as a primary focus of analysis of effectiveness of CDT. Multiple studies including CaVenT trial showed reduced development of PTS. ^{[13, 29, 31, 32]} PTS is linked to poorer long-term health outcomes. ^[33]

The ATTRACT study is a multicenter minimize trial to determine the effectiveness of CDT in prevention of PTS in patients with proximal DVTs. ^{[13, 32]} The investigators used a scoring scale (Villalta PTS scale) to measure severity of the primary endpoint. Per review of the literature, a full study has yet to be published; however, it apparently showed increased recovery from DVT and reduced severity of PTS in patients who underwent CDT. However, CDT did not reduce the incidence of PTS on followup per media reports. ^[32]

Percutaneous mechanical thrombectomy has been developed as an attempt to shorten treatment time and avoid costly intensive care unit (ICU) stays during thrombolytic infusion. Mechanical disruption of venous thrombosis has the potential disadvantage of damaging venous endothelium and valves, in addition to thrombus fragmentation and possible pulmonary embolism (PE). Many devices now exist and are approved for venous use.

Percutaneous mechanical thrombectomy devices are a popular adjunct to catheter-directed thrombolysis. Although these devices may not completely remove a thrombus, they are effective for debulking and for minimizing the dose and time required for infusing a thrombolytic. In patients at high risk for hemorrhagic complications, mechanical thrombectomy may obviate thrombolytic infusion. Such devices are most commonly used to initially restore antegrade flow (in cases of limb threat) or to manage a thrombus that has proved resistant to thrombolysis.

A wide variety of devices are under development or already on the market. These devices macerate a thrombus by use of physical cutting blades, vortex, high-pressure or low-pressure saline jets, suction alone, or ultrasonic liquefaction.

An example is the Trellis catheter, which isolates the thrombosed segment with two occluding balloons and a rotating filament between that mechanically disrupts the thrombus while injecting a thrombolytic agent. After treatment, the thrombus and thrombolytic agent are aspirated, and a venogram is performed. Published data include results with a 97% patency with a single treatment and no bleeding complications in a study group of over 700 patients. ^[34]

The most basic method for mechanical thrombectomy is thromboaspiration, or the aspiration of a thrombus through a sheath. Balloon maceration of the thrombus may be done to facilitate the procedure. The most technically advanced devices, approved primarily for interventions requiring hemodialysis access, may be divided by mechanism into categories of recirculation and fragmentation. Recirculation devices engage the thrombus and destroy it by continuously mixing it by creating a hydrodynamic vortex.

Fragmentation devices leave macroscopic particulate effluent and include devices that chop, brush, or cut the clot. With these devices, concomitant lytic infusion and possible inferior vena cava filter placement are necessary to ensure PE prophylaxis.

Of recirculation devices, only the Trellis-8 Peripheral Infusion System is FDA approved for the treatment of deep venous thrombosis (DVT). The AngioJet System has the broadest FDA-approved uses, including uses in the coronary and peripheral arteries and in obtaining arteriovenous access; this is one of the most effective devices.

Reports have described use of the Arrow-Trerotola, AngioJet, and Helix Clot Buster percutaneous thrombectomy devices for iliofemoral DVT, as well as combined therapy (often with adjunctive thrombolysis, angioplasty and stenting, and placement of an inferior vena cava filter with the Arrow-Trerotola). These devices had 74-100% initial technical and 24-hour clinical success rates. Complete thrombus removal was variable (23-100%). The remainder improved with lytic infusion, with a mean infusion time of 6 hours.

Only one study had a 6% incidence of major bleeding complications. The primary patency rate at 1 year was 85%, and clinical success was obtained in 92%. At 9- to 12-month follow-up, two studies demonstrated an 8% rate of venous insufficiency, whereas two others showed repeat DVT in 15-23%.

Percutaneous mechanical thrombectomy and PTS

Although the literature lacks conclusive evidence, some data support the argument that DVT treated with anticoagulation results in a high risk of PTS 5-10 years later. Active removal of the thrombus with surgery or catheter-directed lysis clears the thrombus relatively quickly and improves preservation of valvular function while reducing the incidence and severity of PTS. However, systemic or catheter-directed pharmacologic thrombolysis entails a high risk of bleeding complications. Initial data suggest that combination therapy that includes percutaneous mechanical thrombectomy, which allows a reduction in the dose and duration of thrombolytic treatment, may achieve thrombus clearance and reduce the incidence of PTS without elevating the bleeding risk.

For more information, see Deep Venous Thrombosis.

The American Society of Hematology (ASH) released their updated recommendations on the management of venous thromboembolism (VTE) (deep vein thrombosis [DVT] and pulmonary embolism [PE]) in October 2020. ^[35] Select recommendations are outlined below.

Strong Recommendations

For patients with PE and hemodynamic compromise, it is recommended that thrombolytic therapy followed by anticoagulation be used over anticoagulation alone.

For patients with DVT and/or PE who have completed primary treatment and will continue vitamin K antagonist (VKA) therapy as secondary prevention, it is recommended that an international normalized ratio (INR) range of 2.0 to 3.0 be used over a lower INR range (eg, 1.5-1.9).

For patients with a recurrent unprovoked DVT and/or PE, indefinite antithrombotic therapy is recommended over stopping anticoagulation after completion of primary treatment.

Conditional Recommendations

Initial management

For patients with DVT and/or PE, the ASH guideline panel suggests using direct oral anticoagulants (DOACs) over VKAs. No single DOAC is suggested over another.

In most patients with proximal DVT, anticoagulation therapy alone is suggested over thrombolytic therapy in addition to anticoagulation.

For patients with PE with echocardiography and/or biomarkers that are compatible with right ventricular dysfunction but without hemodynamic compromise (submassive PE), anticoagulation alone is suggested over the routine use of thrombolysis in addition to anticoagulation.

For patients with extensive DVT in whom thrombolysis is considered appropriate, the ASH guideline panel suggests using catheter-directed thrombolysis over systemic thrombolysis.

For patients with PE in whom thrombolysis is considered appropriate, systemic thrombolysis is suggested over catheter-directed thrombolysis.

For patients with proximal DVT and significant preexisting cardiopulmonary disease, as well as for patients with PE and hemodynamic compromise, use of anticoagulation alone is suggested rather than anticoagulation plus insertion of an inferior vena cava (IVC) filter.

Primary treatment

For primary treatment of patients with DVT and/or PE, whether provoked by a transient risk factor or by a chronic risk factor or unprovoked, using a shorter course of anticoagulation for primary treatment (3-6 months) is suggested over a longer course of anticoagulation for primary treatment (6-12 months).

Secondary prevention

To guide the duration of anticoagulation for patients with unprovoked DVT and/or PE, the ASH guideline panel suggests against routine use of prognostic scores, D-dimer testing, or ultrasonography to detect residual vein thrombosis.

Indefinite antithrombotic therapy is suggested over anticoagulation cessation after completion of primary treatment for the following:

• Patients with DVT and/or PE provoked by a chronic risk factor
• Patients with unprovoked DVT and/or PE

For patients with DVT and/or PE who have completed primary treatment and will continue to receive secondary prevention, use of anticoagulation is suggested over aspirin.

For patients with DVT and/or PE who have completed primary treatment and will continue with a DOAC for secondary prevention, the ASH guideline panel suggests using a standard-dose DOAC or a lower-dose DOAC.

Recurrent events

For patients with breakthrough DVT and/or PE during therapeutic VKA treatment, the ASH guideline panel suggests using low-molecular-weight heparin (LMWH) over DOAC therapy.

For patients who develop DVT and/or PE provoked by a transient risk factor and have a history of previous unprovoked VTE or VTE provoked by a chronic risk factor, indefinite antithrombotic therapy is suggested over stopping anticoagulation after completing primary treatment.

For patients who develop DVT and/or PE provoked by a transient risk factor and have a history of a previous VTE also provoked by a transient risk factor, anticoagulation cessation after completion of primary treatment is suggested over indefinite antithrombotic therapy.

Other

For patients with DVT and/or PE with stable cardiovascular disease (CVD) who initiate anticoagulation and were previously taking aspirin for cardiovascular risk modification, it is suggested that aspirin be suspended over continuing it for the duration of anticoagulation therapy.

For patients with DVT, with or without an increased risk for postthrombotic syndrome (PTS), the ASH guideline panel suggests against the routine use of compression stockings.

Additional resources

For more information, please go to Venous Thromboembolism (VTE), Deep Venous Thrombosis (DVT), and Pulmonary Embolism (PE).

The Society of Interventional Radiology (SIR) released recommendations on the periprocedural management of thrombotic and bleeding risk in patients undergoing percutaneous image-guided interventions in August 2019. ^{[22, 36]}

A multidisciplinary team (cardiology, hematology, or vascular or internal medicine) approach is recommended for planning optimal periprocedural management in patients at high risk for thromboembolic or bleeding events.

Screening coagulation laboratory testing is not routinely recommended for patients with minimal bleeding risk factors who are undergoing procedures with low bleeding risk, but it may be considered for patients receiving warfarin or unfractionated heparin (UFH) or for those with an inherently higher risk of bleeding. Suggested laboratory value thresholds are as follows:

• Correct the international normalized ratio (INR) to within a range of 2.0 to 3.0 or less

• Consider platelet transfusion if the platelet count is below 20 × 10⁹/L

• For low bleeding risk procedures requiring arterial access, the recommended INR threshold is less than 1.8 for femoral access and below 2.2 for radial access

Obtain appropriate preprocedural coagulation testing for patients undergoing procedures with high bleeding risk. Activated partial thromboplastin time is no longer recommended. Suggested laboratory value thresholds are as follows:

• Correct the INR to within a range of 1.5 to 1.8 or less

• Consider platelet transfusion if the platelet count is below 50 × 10⁹/L

In patients with chronic liver disease, judicious use of transfusion of plasma and platelets is recommended owing to the potential for increased portal pressure and transfusion-related adverse events. For patients with chronic liver disease undergoing an invasive procedure, consider adjusting the INR threshold higher and the platelet count threshold lower than in the general population to minimize unnecessary transfusions. It may be useful to measure the fibrinogen level; if it is low, replace with cryoprecipitate.

The guidelines also include a table with management recommendations for nearly two dozen specific anticoagulant and antiplatelet agents.

For more information, please go to Venous Thromboembolism (VTE), Deep Venous Thrombosis (DVT), International Normalized Ratio (INR) Targets: Venous Thromboembolism, and Perioperative Anticoagulation Management.