Quality Improvement Guidelines for the Treatment of Lower Extremity Deep Vein Thrombosis with Use of Endovascular Thrombus Removal

Abstract

LOWER extremity deep vein thrombosis (DVT) is a serious medical condition that can result in death or major disability due to pulmonary embolism (PE), post-thrombotic syndrome (PTS), paradoxical embolization, or limb loss. Since the early 1990s, endovascular methods have been used by interventional radiologists to provide aggressive treatment for lower extremity DVT (1Semba CP Dake MD Iliofemoral deep venous thrombosis: aggressive therapy with catheter-directed thrombolysis.Radiology. 1994; 191: 487-494PubMed Google Scholar). However, there currently exist no published guidelines for the appropriate utilization of these techniques. The Society of Interventional Radiology (SIR) strongly believes that active participation of the interventional radiologist in the patient selection, pretreatment evaluation, patient selection, periprocedural monitoring, and postprocedural care of the DVT patient will improve the safety and effectiveness of these procedures. SIR creates its Standards of Practice documents with use of the following process: Standards documents of relevance and timeliness are conceptualized by the Standards of Practice Committee members. A recognized expert is identified to serve as the principal author, with additional authors assigned depending on the project's magnitude. An in-depth literature search is performed with use of electronic medical literature databases. A critical review of peer-reviewed articles is performed with regard to the study methodology, results, and conclusions. The qualitative weight of these articles is assembled into an evidence table, which is used to write the document such that it contains evidence-based data with respect to content, rates, and thresholds. When the evidence of literature is weak, conflicting, or contradictory, consensus for the parameter is reached by a minimum of 12 Standards of Practice Committee members with use of a Modified Delphi Consensus Method (2Sacks D McClenny TE Cardella JF Lewis CA Society of Interventional Radiology clinical practice guidelines.J Vasc Interv Radiol. 2003; 14: S199-S202Abstract Full Text Full Text PDF PubMed Scopus (1250) Google Scholar). For the purpose of these documents, consensus is defined as 80% participant agreement on a value or parameter. The draft document is critically reviewed by the Standards of Practice Committee members in either a telephone conference call or face-to-face meeting. The revised draft is then sent to the SIR membership for further input/criticism during a 30-day comment period. These comments are discussed by the Standards of Practice Committee members and appropriate revisions are made to create the finished Standards document. Before its publication, the document is endorsed by the SIR Executive Council. The current guidelines are written to be used in quality improvement programs to assess the endovascular treatment of lower extremity DVT. The most important elements of care are (a) pretreatment evaluation and patient selection, (b) performance of the procedure, and (c) postprocedure follow-up care. The outcome measures or indicators for these processes are indications, success rates, and complication rates. Although practicing physicians should strive to achieve perfect outcomes, in practice all physicians will fall short of ideal outcomes to a variable extent. Therefore, in addition to quality improvement case reviews conducted after individual procedural failures or complications, outcome measure thresholds should be used to assess treatment safety and efficacy in ongoing quality improvement programs. For the purpose of these guidelines, a threshold is a specific level of an indicator which, when reached or crossed, should prompt a review of departmental policies and procedures to determine causes and to implement changes, if necessary. Thresholds may vary from those listed here; for example, patient referral patterns and selection factors may dictate a different threshold value for a particular indicator at a particular institution. Therefore, setting universal thresholds is very difficult and each department is urged to adjust the thresholds as needed to higher or lower values to meet its specific quality improvement program situation. The SIR is committed to the basic principles of outcomes-focused, evidence-based medicine. Ideally, every Standards of Practice Committee recommendation would be based on evidence derived from multiple prospective randomized trials of adequate statistical power. Unfortunately, there currently exist no published multicenter randomized trials of significant size that evaluate image-guided endovascular DVT therapies. In evaluating the existing publications, several major limitations are evident: (a) extreme variation in patient selection parameters, definitions of short-term efficacy, and definitions of complications; (b) reliance on surrogate measures of treatment success instead of scientifically rigorous assessment of clinically meaningful outcomes; and (c) absence of systematic assessment of long-term efficacy. For these reasons, the U.S. Food and Drug Administration (FDA) does not currently label any drug or device for endovascular DVT treatment. Streptokinase (administered systemically) did receive FDA approval for DVT in 1980, but a National Institutes of Health consensus panel later recommended against the use of systemic thrombolysis for DVT (3Sherry S Thrombolytic therapy in thrombosis.NIH Consensus Statement Online. 1980; 3: 1-6Google Scholar). The SIR recognizes the potential pitfalls of developing evidence-based DVT standards and of making recommendations regarding the off-label use of drugs and devices based on studies of suboptimal design. However, these difficulties are far outweighed by the potential improvements in safety and treatment efficacy that may be gained by implementing the key lessons learned from the peer-reviewed scientific literature that has evaluated these procedures. The current document was drafted by the DVT Standards and DVT Research Committees of the SIR Venous Forum with further modification by the SIR Standards of Practice Committee and therefore reflects the consensus experience of interventional radiologists with extensive expertise in treating DVT using endovascular means. Given the limited scientific foundation, however, most of the recommendations presented in this document are intended to guide clinical practice rather than to mandate the use of specific methodologies. The authors fully anticipate that these guidelines will be appropriately revised when future studies of greater scientific rigor are available. Venous thromboembolism (VTE) refers to the single common disease entity with two principal manifestations: DVT and PE. A patient with a proved episode of DVT and/or PE is said to have had an episode of VTE. Pulmonary embolism (PE) refers most commonly to the intravascular migration of a venous thrombus to the pulmonary arterial circulation. Proved PE refers to PE that is documented by a positive pulmonary angiogram, an unequivocally positive helical CT scan, a high probability ventilationperfusion scan, surgical observation, or autopsy. Proved PE can be symptomatic (patient had clinical PE symptoms and/or signs such as chest pain, dyspnea, hemoptysis, palpitations, or tachycardia) or asymptomatic (PE was detected on an imaging study in a patient without suggestive symptoms). Suspected PE refers to PE that is suspected based on clinical symptoms and/or signs but for which definitive diagnosis has not been made by imaging or autopsy. Deep vein thrombosis (DVT) refers to the presence of thrombus within a deep vein of the body as proved by diagnostic imaging. Phlegmasia refers to a characteristic clinical picture in which DVT causes massive swelling of the entire extremity. Patients with phlegmasia alba dolens do not have associated cyanosis. Patients with phlegmasia cerulea dolens have more extensive thrombosis with associated cyanosis of the affected limb. This disorder can lead to arterial insufficiency, compartmental compression syndrome (compartment syndrome), and/or venous gangrene and has been associated with a high rate of limb amputation (4Porter JM Rutherford RB Clagett GP et al.Reporting standards in venous disease.J Vasc Surg. 1988; 8: 172-181PubMed Google Scholar). Acute DVT refers to venous thrombosis for which symptoms have been present for 14 days or less or for which imaging studies indicate that venous thrombosis occurred within the last 14 days. Subacute DVT refers to venous thrombosis for which symptoms have been present for 15 to 28 days or for which imaging studies indicate that venous thrombosis occurred within this time interval. Chronic DVT refers to venous thrombosis for which symptoms have been present for more than 28 days or for which imaging findings document the presence of venous thrombosis more than 28 days before. Acute-on-chronic DVT refers to venous thrombosis that has both chronic (> 28 d) and acute (≤ 14 d) components as indicated by symptom history or imaging findings. Proximal DVT refers to complete or partial thrombosis of the popliteal vein, femoral vein (formerly known as the superficial femoral vein), deep femoral vein, common femoral vein, iliac vein, and/or inferior vena cava (IVC). Proximal DVT is often complicated by PE. Proximal DVT can be further subclassified as follows: Femoropopliteal DVT refers to complete or partial thrombosis of the popliteal vein, femoral vein, and/or deep femoral vein. Iliofemoral DVT refers to complete or partial thrombosis of any part of the iliac vein and/or the common femoral vein, with or without associated femoropopliteal DVT. Calf vein DVT refers to complete or partial thrombosis of one or more deep calf veins, including the anterior tibial veins, posterior tibial veins, peroneal veins, and/or deep muscular veins. Isolated calf vein DVT is rarely associated with symptomatic PE (5Buller HR Hull RD Hyers TM et al.Antithrombotic therapy for venous thromboembolic disease. The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy.Chest. 2004; 26: 401S-428SCrossref Scopus (1309) Google Scholar). When calf vein DVT propagates into the popliteal vein, it is considered proximal DVT. Pharmacologic thrombolysis refers to administration of drugs with thrombolytic activity. Several different routes of administration can be used: Systemic thrombolysis refers to pharmacologic thrombolytic agent delivery through an intravenous line located distant from the affected extremity. Flow-directed thrombolysis refers to pharmacologic thrombolytic agent delivery through a pedal intravenous line placed within the affected extremity, with or without the use of tourniquets to intermittently compress the saphenous system to direct the drug into the deep venous system. Catheter-directed intrathrombus thrombolysis (CDT) refers to pharmacologic thrombolytic agent delivery through an infusion catheter and/or wire that is embedded within the thrombosed vein being treated. Lacing refers to the use of a catheter to disperse a bolus dose of the thrombolytic drug throughout the thrombus. Percutaneous mechanical thrombectomy (PMT) refers to the percutaneous use of catheter-based mechanical devices that contribute to thrombus removal via fine (microscopic) thrombus fragmentation, maceration, and/or aspiration. Pharmacomechanical thrombolysis refers to thrombus dissolution via any simultaneous use of pharmacologic thrombolysis and mechanical thrombectomy. Pulse-spray pharmacomechanical thrombolysis refers to a specific technique in which a thrombolytic drug is periodically forcefully injected into the thrombus (6Bookstein JJ Fellmeth B Roberts A et al.Pulsed-spray pharmacomechanical thrombolysis: preliminary clinical results.AJR. 1989; 152: 1097-1100Crossref PubMed Scopus (140) Google Scholar). Aspiration thrombectomy refers to the use of a syringe to aspirate thrombus from the clotted vein via a catheter or sheath. Balloon maceration refers to the use of a catheter-mounted angioplasty balloon to produce gross (macroscopic) thrombus fragmentation or maceration. Balloon angioplasty refers to inflation of a catheter-mounted angioplasty balloon with the specific intent of enlarging the venous lumen. Stent placement refers to catheterbased deployment of a metallic endoprosthesis to enlarge and maintain the venous lumen. Surgical thrombectomy refers to the use of open surgical techniques, including venotomy, to remove thrombus from the deep veins of the body. Therapeutic-level heparin administration refers to the intravascular use of unfractionated heparin to raise the partial thromboplastin time (PTT) to 1.5 to 2.5 times control. Subtherapeutic heparin refers to the intravascular use of unfractionated heparin at lower doses to prevent pericatheter thrombosis (PTT < 1.5 times control). Major bleeding is defined as intracranial bleeding or bleeding severe enough to result in death, surgery, cessation of therapy, or blood transfusion (7Patel N Sacks D Patel RI et al.SIR reporting standards for the treatment of acute limb ischemia with use of transluminal removal of arterial thrombus.J Vasc Interv Radiol. 2003; 14: S453-S465Abstract Full Text Full Text PDF PubMed Scopus (60) Google Scholar). Minor bleeding is defined as less severe bleeding manageable with local compression, sheath upsizing, and/or dose alterations of a pharmacologic thrombolytic agent, anticoagulant, or antiplatelet drug. Progression of DVT is defined as imaging-proved extension of an existing DVT into at least one previously uninvolved venous segment. Recurrent VTE is defined as the presence of a new proved PE or recurrent DVT in a patient with at least one prior episode of VTE. Recurrent DVT is defined as imaging-proved DVT involving a new venous segment or a previously involved venous segment for which symptomatic and imaging improvement had been obtained in a patient with at least one prior episode of DVT. Post-thrombotic syndrome (PTS) refers to a symptom complex that is commonly observed after one or more episodes of DVT. PTS is often characterized by limb edema, heaviness, pain, venous claudication, and limb hyperpigmentation, with a minority of patients developing severe manifestations such as venous ulceration. A careful medical history and directed physical examination will usually yield most of the information needed to determine the appropriateness of endovascular therapy. Patients should be queried about known VTE risk factors, details of prior VTE episodes and treatments, the duration and exact nature of preexisting and more recent limb symptoms, and common PE symptoms such as dyspnea, chest pain, palpitations, hemoptysis, and syncope. Identification of PE is important because systemic PE thrombolysis, surgical pulmonary thrombectomy, or endovascular pulmonary thrombectomy may be more appropriate for unstable PE patients and stable PE patients with echocardiographic right ventricular dysfunction (“submassive PE”) (5Buller HR Hull RD Hyers TM et al.Antithrombotic therapy for venous thromboembolic disease. The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy.Chest. 2004; 26: 401S-428SCrossref Scopus (1309) Google Scholar, 8Konstantinides S Geibel A Heusel G et al.Heparin plus alteplase compared with heparin alone in patients with submassive pulmonary embolism.N Engl J Med. 2002; 347: 1143-1150Crossref PubMed Scopus (888) Google Scholar). Important comorbidities to identify include factors that might promote bleeding complications (such as active ongoing bleeding; previous or current intracranial disease; recent trauma, surgery, or percutaneous procedures; severe hepatic dysfunction; gastrointestinal bleeding history; and severe uncontrolled hypertension), pulmonary hypertension and other cardiopulmonary diseases, renal failure, and active infection. Prior to thrombolysis, patients with malignancies known to metastasize to the central nervous system should undergo brain imaging to exclude the presence of lesions that might bleed. The patient's medications and drug allergies should be reviewed, and particular note should be taken of medications that influence coagulation or platelet function. The patient's life expectancy and anticipated activity level are also important to factor into the global assessment of the patient's suitability for endovascular therapy. Because VTE symptoms tend to be nonspecific, the clinical assessment should be supplemented with imaging confirmation. In patients with suggestive symptoms, the presence of PE is typically established with contrastenhanced helical CT scanning or ventilation-perfusion scanning, although catheter angiography is occasionally needed. The anatomical extent of DVT often influences decisions of whether to use endovascular therapy and can usually be determined noninvasively. In patients with calf swelling, compression duplex sonography can characterize the extent of thrombus in the popliteal, femoral, and common femoral veins with high accuracy (9Douglas MG Sumner DS Duplex scanning for deep vein thrombosis: has it replaced both phlebography and non-invasive testing?.Semin Vasc Surg. 1996; 9: 3-12PubMed Google Scholar, 10Tick LW Ton E van Voorthuizen T et al.Practical diagnostic management of patients with clinically suspected deep vein thrombosis by clinical probability test, compression ultrasonography, and D-dimer test.Am J Med. 2002; 113: 630-635Abstract Full Text Full Text PDF PubMed Scopus (84) Google Scholar, 11Prandoni P Bernardi E Tormene D et al.Diagnosis of recurrent deep vein thrombosis.Semin Vasc Med. 2001; 1: 55-60Crossref PubMed Scopus (10) Google Scholar). The hallmark finding of DVT on duplex sonography is venous noncompressibility. Other findings may include visualized intraluminal material, absence of flow on augmentation, lack of respiratory variation, and/or incomplete color filling. One pitfall can occur when a duplicated femoral vein is present: DVT in the accessory vein may be missed if the duplication is not recognized (12Quinlan DJ Alikhan R Gishen P Sidhu PS Variations in lower limb venous anatomy: implications for US diagnosis of deep vein thrombosis.Radiology. 2003; 228: 443-448Crossref PubMed Scopus (67) Google Scholar). Duplex sonography has only 70% to 85% accuracy for calf vein thrombosis, but its presence rarely affects decisions of whether to use endovascular therapy (13Kamida CB Kistner RL Eklof B Masuda EM Lower extremity ascending and descending phlebography.in: Gloviczki P Yao JST Handbook of Venous Disorders, 2nd ed: Guidelines of the American Venous Forum. Arnold, Great Britain2001: 132-139Google Scholar, 14Elias A LeCorff G Bouvier JL Value of real-time ultrasound imaging in the diagnosis of deep vein thombosis of the lower limbs.Int Angiol. 1987; 6: 175-182PubMed Google Scholar, 15Mitchell DC Grasty MS Stebbings WSL et al.Comparison of duplex ultrasonography and venography in the diagnosis of deep venous thrombosis.Br J Surg. 1991; 78: 611-613Crossref PubMed Scopus (66) Google Scholar). If thigh swelling is present or if the common femoral vein is abnormal on ultrasonogram, then imaging of the iliocaval venous system may be performed to define the upper extent of the thrombus. Contrast-enhanced CT scanning, MR imaging, and duplex US are commonly used for this purpose. However, it must be noted that at the time of writing, no CT or MR imaging method of evaluating the iliocaval veins had been validated for DVT diagnosis (16Roh BS Park KH Kim EA et al.Prognostic value of CT before thrombolytic therapy in iliofemoral deep venous thrombosis.JVIR. 2002; 13: 71-76Abstract Full Text Full Text PDF Scopus (10) Google Scholar, 17Fraser DG Moody AR Morgan PS et al.Diagnosis of lower-limb deep venous thrombosis: a prospective blinded study of magnetic resonance direct thrombus imaging.Ann Intern Med. 2002; 136: 89-98Crossref PubMed Scopus (253) Google Scholar). When endovascular therapy is planned, a baseline hematocrit, platelet count, INR, PTT, creatinine, and serum human chorionic gonadotropin level (in women of childbearing age) should be obtained prior to treatment. A preprocedure fibrinogen level, while not required, is also recommended to serve as a baseline for later comparison. For any particular DVT patient, the decision to use endovascular therapy depends on a balanced assessment of the likelihood that the patient will experience treatment success, the degree to which this benefit would be clinically meaningful to the patient, and the likelihood that the patient will suffer a major complication. The challenge in making this clinical determination is heightened by the lack of conclusive randomized trial data that characterize the actual safety and efficacy of endovascular DVT interventions. Hence, at present, decisions concerning the use of endovascular DVT therapy should be highly individualized and based on a rigorous pretreatment assessment of the patient. The patient must be informed of all the risks of therapy, the possible lack of long-term benefits, and the existence of alternative treatment methods. The evidence basis pertaining to the treatment of lower extremity DVT using pharmacologic catheter-directed intrathrombus thrombolysis (CDT) with adjunctive balloon angioplasty and/or stent placement is considered sufficient to support limited recommendations regarding thresholds for indications, success rates, and complications. Acceptable indications for CDT for lower extremity DVT are described here and are summarized in Table 1. The suggested threshold for these indications is 95%.Table 1Indications for Pharmacologic Catheter-Directed ThrombolysisIndication*The suggested threshold for these indications is 95%.Acceptable Bleeding RiskLife ExpectancyPrimary GoalsPhlegmasia cerulea dolensLow-ModerateAnyLimb salvageSurvivalAcute/subacute IVC thrombosisLow-ModerateAnyPE preventionPreserve organsSymptom reliefAcute iliofemoral DVTLowLongPrevent PTSAcute femoropopliteal DVTLowLongPrevent PTSSubacute/chronic iliofemoral DVTLow†When thrombolytic therapy is being used.LongAlleviate PTSPrevent PTS* The suggested threshold for these indications is 95%.† When thrombolytic therapy is being used. Open table in a new tab 1.Phlegmasia cerulea dolens in patients with low or moderate bleeding risk. The use of CDT for phlegmasia cerulea dolens is predicated on anecdotal evidence of immediate efficacy and the unsatisfactory performance of other therapies. Surgical thrombectomy can also be effective in rapidly restoring venous outflow but often results in incomplete thrombus removal, recurrent DVT, and systemic complications in these extremely ill patients (18Eklof B Arfvidsson B Kistner RL Masuda EM Indications for surgical treatment of iliofemoral vein thrombosis.Hematol Oncol Clin North Am. 2000; 14: 471-482Abstract Full Text Full Text PDF PubMed Scopus (27) Google Scholar). Multiple case reports and small series attest to the ability of CDT to provide limb salvage for these patients without exposing them to the risks of surgery (19Patel NH Plorde JJ Meissner M Catheter-directed thrombolysis in the treatment of phlegmasia cerulea dolens.Ann Vasc Surg. 1998; 12: 471-475Abstract Full Text PDF PubMed Scopus (60) Google Scholar, 20Robinson DL Teitelbaum GP Phlegmasia cerulea dolens: treatment by pulse-spray and infusion thrombolysis.AJR. 1993; 160: 1288-1290Crossref PubMed Scopus (35) Google Scholar). Given the high rates of limb amputation and death observed with other therapies, the risks of CDT are clearly justified for most phlegmasia cerulea dolens patients (21Weaver FA Meacham PW Adkins RB Dean RH Phlegmasia cerulea dolens: therapeutic considerations.South Med J. 1988; 81: 306-312Crossref PubMed Scopus (79) Google Scholar). Patients thought to be at high risk for bleeding may be candidates for surgical thrombectomy. When phlegmasia cerulea dolens is present, endovascular or surgical thrombus removal should be performed on an emergency basis.2.Acute or subacute IVC thrombosis causing moderate to severe pelvic congestion, moderate to severe limb symptoms, and/or compromise of venous drainage from visceral organs in patients with low or moderate bleeding risk. IVC syndrome can create major clinical problems beyond those experienced by patients with less extensive forms of DVT. First, the discomfort associated with acute IVC thrombosis can be quite severe, particularly when severe venous congestion involves the external genitalia. Second, extension of thrombus into the suprarenal IVC, renal veins, and/or hepatic veins can lead to acute renal failure or Budd-Chiari syndrome. Third, the presence of IVC thrombus can preclude the placement of an IVC filter for PE prophylaxis. For these reasons, treatment of IVC thrombosis via CDT is often justified to prevent PE, preserve visceral organ function, and obtain immediate symptom relief in patients at low or moderate bleeding risk. Patients thought to be at high risk for bleeding complications may be candidates for surgical thrombectomy.3.Acute iliofemoral DVT in ambulatory patients with low bleeding risk and long life expectancy. Patients with acute iliofemoral DVT tend to be highly symptomatic and may be at particularly high risk for recurrent DVT, PTS, and late disability (22Douketis JD Crowther MA Foster GA Ginsberg JS Does the location of thrombosis determine the risk of disease recurrence in patients with proximal deep vein thrombosis?.Am J Med. 2001; 110: 515-519Abstract Full Text Full Text PDF PubMed Scopus (193) Google Scholar, 23Strandness DE Langlois Y Cramer M et al.Long-term sequelae of acute venous thrombosis.JAMA. 1983; 250: 1289-1292Crossref PubMed Scopus (338) Google Scholar, 24Delis KT Bountouroglou D Mansfield AO Venous claudication in iliofemoral thrombosis: long-term effects on venous hemodynamics, clinical status, and quality of life.Ann Surg. 2004; 239: 118-126Crossref PubMed Scopus (294) Google Scholar). CDT can remove venous thrombus, provide immediate symptom relief, and facilitate stent treatment of underlying venous stenoses (1Semba CP Dake MD Iliofemoral deep venous thrombosis: aggressive therapy with catheter-directed thrombolysis.Radiology. 1994; 191: 487-494PubMed Google Scholar).The primary justification for using CDT to treat iliofemoral DVT is its potential to reduce the frequency and severity of PTS. This relationship has not been conclusively established but is supported by several compelling lines of indirect evidence: (a) Absence of venous thrombus on follow-up duplex ultrasonogram after an episode of DVT has been associated with a reduced rate of recurrent DVT, the major risk factor for PTS (25Prandoni P Lensing AW Prins MH et al.Residual venous thrombosis as a predictive factor of recurrent venous thromboembolism.Ann Intern Med. 2002; 137: 955-960Crossref PubMed Scopus (470) Google Scholar, 26Prandoni P Lensing AW Cogo A et al.The long-term clinical course of acute deep venous thrombosis.Ann Intern Med. 1996; 125: 1-7Crossref PubMed Scopus (1936) Google Scholar); (b) thrombus removal via surgical thrombectomy or systemic thrombolysis has been associated with reduced rates of PTS in randomized trials (27Arnesen H Hoiseth A Ly B Streptokinase or heparin in the treatment of deep vein thrombosis.Acta Med Scand. 1982; 211: 65-68Crossref PubMed Scopus (218) Google Scholar, 28Elliot MS Immelman EJ Jeffery P A comparative randomized trial of heparin versus streptokinase in the treatment of acute proximal venous thrombosis: an interim report of a prospective trial.Br J Surg. 1979; 66: 838-843Crossref PubMed Scopus (251) Google Scholar, 29Watson MI Armon MP Thrombolysisforacutedeepveinthrombosis.Cochrane Database Syst Rev. 2004; 1: 1-66Google Scholar, 30Plate G Eklof B Norgren L et al.Venous thrombectomy for iliofemoral venous thrombosis: 10-year results of a prospective randomized study.Eur J Vasc Endovasc Surg. 1997; 14: 333-343Abstract Full Text PDF PubMed Scopus (209) Google Scholar, 31Eklof B Kistner RL Is there a role for thrombectomy in iliofemoral venous thrombosis?.Semin Vasc Surg. 1996; 9: 34-45PubMed Google Scholar); (c) in a retrospective case-control study, acute iliofemoral DVT patients treated with successful CDT plus anticoagulation experienced reduced PTS and improved health-related quality of life at midterm follow-up compared with a matched control group who received anticoagulation alone (32Comerota AJ Throm RC Mathias S et al.Catheter-directed thrombolysis of iliofemoral deep venous thrombosis improves health-related quality of life.J Vasc Surg. 2000; 32: 130-137Abstract Full Text Full Text PDF PubMed Scopus (307) Google Scholar); and d) a single-center randomized trial and another nonrandomized study found improved limb outcomes in iliofemoral DVT patients treated with CDT plus anticoagulation compared with patients who received anticoagulation alone at follow-up of 6 months and 5 years, respectively (33AbuRahma AF Perkins SE Wulu JT Ng HK Iliofemoral deep vein thrombosis: conventional therapy versus lysis and percutaneous transluminal angioplasty and stenting.Ann Surg. 2001; 233: 752-760Crossref PubMed Scopus (209) Google Scholar, 34Elsharawy M Elzayat E Early results of thrombolysis vs anticoagulation in iliofemoral venous thrombosis: a randomised clinical trial.Eur J Vasc Endovasc Surg. 2002; 24: 209-214Abstract Full Text PDF PubMed Scopus (336) Google Scholar).Therefore, CDT is an acceptable and possibly superior method of treating acute iliofemoral DVT in ambulatory patients with long life expectancy who are considered to be at low risk for bleeding. In patients at moderate or high risk of bleeding, surgical thrombectomy may be considered.4.Acute femoropopliteal DVT in highly symptomatic ambulatory patients with low bleeding risk and long life expectancy. In patients with acute femoropopliteal DVT, the use of CDT is based on its potential to pr