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Prevention and treatment of thromboembolic and ischemic complications associated with endovascular procedures: Part II--Clinical aspects and recommendations.

We reviewed the incidence, risk factors, and clinical features of thromboembolic and ischemic events associated with diagnostic cerebral angiography, endovascular treatment of aneurysms using coils or balloons, angioplasty and stent placement to treat extracranial carotid artery stenosis, and embolization of arteriovenous malformations using glue or other embolic agents. We performed a cumulative analysis to determine the frequency and characteristics of these events and a subset analysis (whenever possible) to determine the benefits of various strategies for complication avoidance. Of the 1,547 patients who underwent Guglielmi detachable coil treatment, thromboembolic events were observed for 127 (8.2%), consisting of asymptomatic events for 12 patients, transient ischemic attacks for 29, and strokes for 86. The outcomes for the 86 patients with strokes were categorized as full recovery for 15, good recovery for 27, partial recovery for 19, no recovery for 11, death for 12, and undetermined outcome for 2. Of the 834 patients who underwent carotid angioplasty and stent placement, thromboembolic events were observed for 73 (8.8%), consisting of transient ischemic attacks for 26 patients and strokes for 47. The outcomes for the patients with strokes were categorized as full recovery for 20, good recovery for 15, partial recovery for 6, no recovery for 2, and death for 4. High rates of thromboembolic events were also observed with balloon occlusion of aneurysms (11%) or parent arteries (19%) and carotid angioplasty alone (5.9%). Arteriovenous malformation embolization was associated with an ischemic event/procedure rate of 9.4%. High rates of thromboembolic and ischemic complications, with subsequent morbidity and death, are associated with most endovascular procedures. Further research and the formulation of standard preventive guidelines may help to reduce these risks and improve the overall success of these procedures.

Angioplasty, Balloon↗

Thromboembolic complications after major thoracolumbar spine surgery.

STUDY DESIGN: Adult spinal surgery patients were studied prospectively to determine the incidence of subclinical deep venous thrombosis. An overlapping group of patients was reviewed retrospectively for symptomatic thromboembolism. OBJECTIVES: To determine the incidence of symptomatic and asymptomatic thromboembolism in spinal surgery patients. SUMMARY OF BACKGROUND DATA: Although thromboembolic complications are known to occur after spinal operations, there are limited published data on the incidence of pulmonary embolus or deep venous thrombosis after major spinal surgery. METHODS: One hundred sixteen adult spinal surgery patients were examined with duplex ultrasound to determine the incidence of deep venous thrombosis. Seventy-three of these patients also underwent lung perfusion scans to look for subclinical pulmonary embolism. A retrospective review was conducted of symptomatic thromboembolic complications occurring in a 2-year period at the authors' center. Three hundred and eighteen major spinal reconstructive procedures were performed during the period reviewed, which included the period of the prospective study and therefore the patients of the prospective group. Thigh-length compression stockings and pneumatic compression leggings were used for prophylaxis in all patients. RESULTS: One patient had an asymptomatic iliac vein thrombosis, and seven patients had symptomatic pulmonary embolism (2.2%). Six of the symptomatic pulmonary emboli occurred after combined anterior/posterior spinal fusions (6%), whereas only one occurred after posterior decompression and fusion (0.5%). CONCLUSIONS: Duplex ultrasound appeared insensitive for diagnosing clots before embolization in this patient group. Simple mechanical prophylaxis for thromboembolism, which may be adequate for patients undergoing posterior procedures, may not be as protective for patients undergoing combined anterior/posterior spine surgery.

Female↗

Prophylaxis of venous thromboembolism in medical patients.

Prophylaxis of venous thromboembolism in medical patients is an area where the potential benefits to patients are great. Venous thromboembolism is at least as common among medical as it is among surgical patients. Despite the widespread use of thromboprophylaxis in surgical patients, fatal pulmonary embolism is one of the most common causes of preventable death in the hospital. This may result from underuse of thromboprophylaxis in medical patients. The incidence of venous thromboembolism varies, but a history of previous venous thromboembolism, age 40 years and older, immobility, and specific illnesses such as stroke, myocardial infarction, heart failure, and cancer put patients at particular risk. Most early studies assessed the use of anticoagulants such as unfractionated heparin, low-molecular-weight heparin, and warfarin at reducing the incidence of venous thromboembolism in surgical patients. More recent studies and those currently being carried out are assessing the role of thromboprophylaxis in general medical patients and those with specific medical illnesses. As the evidence accumulates and guidelines are strengthened physicians will be able to tailor the use of thromboprophylaxis to the individual patient's needs.

Anticoagulants↗

Subcutaneous unfractionated heparin compared with low-molecular-weight heparin for the initial treatment of venous thromboembolism.

PURPOSE OF REVIEW: Low-molecular-weight heparin is the preferred choice for the initial treatment of acute, uncomplicated venous thromboembolism. In this context, unfractionated heparin is as safe and effective as low-molecular-weight heparin but requires strict laboratory monitoring. Twice-daily subcutaneous unfractionated heparin is more effective than, and as safe as, intravenous unfractionated heparin and may simplify patient treatment in or out of the hospital, being possibly cost saving, especially if it is used in weight-based, fixed, unadjusted doses. The present review focuses on the relative values of low-molecular-weight heparin and subcutaneous unfractionated heparin for the initial treatment of venous thromboembolism. RECENT FINDINGS: The major advantages of low-molecular-weight heparin over unfractionated heparin seem to be ease of administration and cost savings associated with home therapy or early hospital discharge; however, many patients with venous thromboembolism are still admitted to the hospital for treatment, and unfractionated heparin is extensively used to this purpose, especially in the United States. Subcutaneous unfractionated heparin, adjusted according to activated partial thromboplastin time algorithms, is as safe and effective as low-molecular-weight heparin for the treatment of venous thromboembolism, allows for quick mobilization and early discharge of suitable patients, and represents a cost-effective strategy. Fixed-dose unfractionated heparin, like low-molecular-weight heparin, may be used for the home treatment of deep vein thrombosis. SUMMARY: Subcutaneous unfractionated heparin, targeted on activated partial thromboplastin time results or in fixed doses, may be used in or out of the hospital for the treatment of venous thromboembolism, being possibly cost effective; however, these findings need confirmation through appropriate, large-sample, randomized clinical trials.

Algorithms↗

Pulmonary angiography for the diagnosis of thromboembolic events in the non-human primate.

BACKGROUND: Evaluating possible thromboembolic events in the non-human primate has traditionally required euthanasia, significantly limiting the ability to conduct longitudinal studies. We hypothesized that pulmonary angiography could offer a safe, reproducible, and non-lethal means to assess for pulmonary embolus in the non-human primate. METHODS: Eleven rhesus primates were studied using standard pulmonary angiography techniques. Five animals studied had previously received humanized anti-CD154 antibodies (associated with thromboembolism risk) in the context of skin transplantation 2 years before the angiography study. Four primates were studied after receiving mouse anti-human CD154 antibody following allogeneic islet or skin transplantation. RESULTS: Angiography was successful in all primates. We observed no complications, and all animals promptly recovered from the procedure. Angiographic findings consistent with thromboembolism were demonstrated in the three primates actively receiving anti-CD154 antibody and in one primate that last received anti-CD154 nearly 2 years before the study. The study was normal in both the streptozotocin-induced diabetic control animals. Histopathology of the lungs confirmed thrombus in two of the four primates, but no thromboembolus was identified in the other two. The first had limited pathologic evaluation without fine slices, and in the second (treated 2 years before with a humanized anti-CD154), ascariasis was found in the area identified as abnormal by the angiogram. CONCLUSIONS: Minimally invasive pulmonary angiography is a safe, reproducible, and inexpensive method to assess possible thromboembolic events in the non-human primate. This method may allow for the longitudinal assessment of non-human primates given novel agents that may promote thromboembolism.

Angiography, Digital Subtraction↗

Individual time within target range in patients treated with vitamin K antagonists: main determinant of quality of anticoagulation and predictor of clinical outcome. A retrospective study of 2300 consecutive patients with venous thromboembolism.

The efficacy and safety of vitamin K antagonists (VKA) are related to the actual level of anticoagulation (given as the international normalized ratio, INR). It is often difficult to maintain an optimal INR over time. We assessed the clinical impact of the individual time spent within INR target range (ITTR) in 2304 consecutive patients with venous thromboembolism. Annual incidences of recurrent thromboembolism and major bleeding were 6.2% and 2.8% respectively. The relative risk (RR) of thromboembolism was 4.5 [95% confidence interval (CI) 3.1-6.6, P < 0.001] at INR < 2.0, for major bleeding it was 6.4 (2.5-16.1, P < 0.001) at INR > 5.0, compared with INR 2.0-3.0. Patients with ITTR < 45% were at higher risk than those with ITTR > 65% (RR 2.8, 1.9-4.3, P < 0.001), while no difference was demonstrated comparing ITTR 45-65% and ITTR > 65% (RR 1.2, 0.7-1.8, P = 0.54). Annual incidences of recurrent thromboembolism were 16.0%, 4.9% and 4.6% at ITTR < 45%, 45-60% and >65% respectively. For major bleeding these were 8.7%, 2.1% and 1.9% respectively. ITTR < 37% during the first 30 treatment days was highly predictive for the total treatment time ITTR < 45% (RR 24.2, 13.5-43.1, P < 0.001). In conclusion, ITTR can be used to identify patients on VKA at risk of recurrent thromboembolism or major bleeding. Since the 30-d ITTR is highly predictive for total treatment ITTR, these patients can be identified soon after start of treatment.

Anticoagulants↗

The role of transesophageal echocardiography in the management of patients with acute and chronic pulmonary thromboembolism.

UNLABELLED: Acute and chronic pulmonary thromboembolism carry high mortality. The role of transesophageal echocardiography (TEE), however, has not been well delineated in patients with suspected pulmonary thromboembolism. The aim of the present study was to demonstrate the value of Tee in patients with various clinical manifestations of pulmonary thromboembolic disease. Twelve patients--ten males and two females, age 47-85 years--are presented in whom central pulmonary thromboembolism was found by TEE. Six patients were referred for breathlessness and had moderate to severe pulmonary hypertension (PH) with (3) or without (1) right atrial thrombus or had right heart dilatation (1) or right ventricular myxoma (1) on transthoracic echocardiography (TTE). Thrombolysis (2), surgery (2), and heparin (2) treatment was performed without angiography. All but one patient recovered. Six patients had severe PH by TTE, one of them had a right atrial thrombus. Angiography was done in five patients in whom surgery was considered. Pulmonary thromboendarterectomy was successfully performed in two patients, it was contraindicated in two patients for advanced age or severe left ventricular dysfunction, both patients died during follow-up, and two patients were waiting for surgery. IN CONCLUSION: TEE has a definite role in the management of patients with acute pulmonary thromboembolism or in pulmonary embolism associated with right-sided intracardiac masses and in the selection of patients with PH for pulmonary thromboendarterectomy.

Acute Disease↗

Comparison of bronchopulmonary collaterals and collateral blood flow in patients with chronic thromboembolic and primary pulmonary hypertension.

OBJECTIVE: To compare the visualisation of bronchopulmonary collaterals and bronchopulmonary collateral blood flow in patients with chronic thromboembolic pulmonary hypertension 2nd primary pulmonary hypertension. SETTING: Referral centre for cardiology at an academic hospital. PATIENTS: Nine patients with chronic thromboembolic pulmonary hypertension and 17 with primary pulmonary hypertension. INTERVENTIONS: Bronchopulmonary collaterals were visualised by selective bronchial arteriography or thoracic aortography. Bronchopulmonary collateral blood flow was estimated by injecting indocyanine green into the ascending aorta and sampling below the mitral valve from the left ventricle. RESULTS: The degree of pulmonary hypertension was comparable in the two groups. Large bronchopulmonary collaterals were visualised in all the patients with thromboembolic pulmonary hypertension who had bronchial arteriography or aortography or both. None of the primary pulmonary hypertension group studied by aortography had bronchopulmonary collaterals (P < < 0.001). All the patients with chronic thromboembolic pulmonary hypertension had significant bronchopulmonary collateral blood flow, which was (mean (SD)) 29.8 (18.6)% of the systemic blood flow. There was no recordable collateral blood flow in 11 of 15 patients with primary pulmonary hypertension. In the remaining four patients the mean value was 1.1 (1.8)% of the systemic blood flow (P < < 0.001). CONCLUSIONS: Visualisation of bronchopulmonary collaterals by thoracic aortography or by bronchial arteriography, or the demonstration of an increased bronchopulmonary collateral flow, helps to distinguish patients with chronic thromboembolic pulmonary hypertension from those with primary pulmonary hypertension.

Aortography↗

[Risk and prevention of thromboembolism complications in gynecologic malignancies].

Gynecologic malignancies are often associated with deep vein thrombosis and pulmonary embolism, even before treatment is begun. But such complications also happen during treatment, also if thromboembolism prophylaxis is performed. The incidence of pulmonary embolism before treatment was investigated using scintigraphy. In a retrospective and in a prospective randomized trial, various methods of thromboembolism prophylaxis were evaluated during primary or postoperative radiation therapy. Pulmonary embolism was present in 11.9% of the patients admitted with uterine malignancy. Retrospectively, there were deep vein thromboses in 6.8%, pulmonary embolisms in 3.8% and bleeding complications in 5.3% of the patients receiving thromboembolism prophylaxis with acenocoumarol during radiation therapy of cervical and endometrial cancer. In the prospective study, deep vein thromboses occurred in 1.5%, pulmonary embolisms in 5.9% and bleedings in 2.2%, with both the LMW heparin and the acenocoumarol groups presenting similar results. Thromboembolism is a frequent paraneoplasia of uterine malignancies. The prevention of thromboembolic complications during radiation therapy of uterine malignancies is efficacious and safe using either LMW heparin or acenocoumarol.

Acenocoumarol↗

Body mass index and thromboembolic stroke in nonsmoking men in older middle age. The Honolulu Heart Program.

BACKGROUND AND PURPOSE: While evidence suggests that obesity has an independent relation to coronary artery disease, similar findings for stroke have not been established. The purpose of this study was to examine the relation between body mass index and the risk of thromboembolic stroke independently of other risk factors. METHODS: Since 1965, the Honolulu Heart Program has followed a cohort of men in a prospective study of cardiovascular disease. This article examines the relationship between the baseline measurement of body mass index and the risk of thromboembolic stroke in 1163 nonsmoking men in older middle age (55 to 68 years). Men who had an elevated risk of stroke due to hypertension, diabetes, and other risk factors were excluded from the analysis. RESULTS: After 22 years of follow-up, the rate of stroke increased significantly with increasing levels of body mass (P < .01). In the bottom tertile of the body mass index, the rate of thromboembolic stroke was 28.7 per 1000 (11/383). In the middle tertile, the rate was increased by 40% to 40.7 per 1000 (16/393), and in the top tertile, the rate of thromboembolic stroke was 55.4 per 1000 (21/387), a twofold excess compared with the bottom tertile. After adjustment for age and the residual effects of confounding risk factors, including systolic blood pressure and serum glucose, the estimated relative risk of stroke for the average body mass index in the top tertile (26.6 kg/m2) compared with that in the bottom tertile (20.3 kg/m2) was 2.1 (95% confidence interval, 1.1 to 4.1). These findings were not affected by coronary events that occurred in the course of follow-up, nor did they appear to be influenced by deaths from other causes. CONCLUSIONS: We conclude that elevated body mass is associated with an increased risk of thromboembolic stroke in nonsmoking men in older middle age who are free of commonly observed conditions related to cardiovascular disease.

Age Factors↗

Changes of circadian blood pressure patterns after hemodynamic and thromboembolic brain infarction.

BACKGROUND AND PURPOSE: We investigated the changes of circadian blood pressure patterns after thromboembolic and hemodynamic brain infarction and evaluated the relation between circadian blood pressure variation, infarct location, and activation of the autonomic nervous system after thromboembolic stroke. METHODS: Repeated 24-hour blood pressure measurements were performed in 45 patients with proven first-ever brain infarctions of different origins. Evaluation of serum norepinephrine concentration, prolongation of the QT interval, and degree of cardiac arrhythmias were used to determine the extent of sympathetic activation after thromboembolic stroke. RESULTS: Whereas circadian blood pressure variation was significantly increased after hemodynamic infarction compared with a control group (diastolic, -25.2 +/- 4.5% versus -13.8 +/- 6.5%; p < .005), a clearly reduced variation was observed after thromboembolic infarction (diastolic, -5.2 +/- 6.9%). Blood pressure variation was positively related to serum norepinephrine concentration (r = .79; P < .01) after thromboembolic infarction. Patients with involvement of the insular cortex showed a nocturnal rise of blood pressure significantly more frequently (66.7% versus 11.8%; P < .005) and had higher norepinephrine levels (66.7 +/- 110 pg/mL versus 290 +/- 178 pg/mL; P < .01) than patients without insular cortex infarction, indicating increased sympathetic activity. This was associated with a significantly more frequent occurrence of QT prolongation and cardiac arrhythmias. CONCLUSIONS: The observed differences in circadian blood pressure patterns may (1) help to distinguish the pathophysiological basis of the stroke, (2) help to explain worsening in some cases of hemodynamic stroke, (3) confirm the importance of the insular cortex for sympathetic activation, and (4) identify subgroups of patients with increased risk of myocardial infarction and arrhythmia.

Aged↗

The relationship of the factor V Leiden mutation or the deletion-deletion polymorphism of the angiotensin converting enzyme to postoperative thromboembolic events following total joint arthroplasty.

BACKGROUND: Although all patients undergoing total joint arthroplasty are subjected to similar risk factors that predispose to thromboembolism, only a subset of patients develop this complication. The objective of this study was to determine whether a specific genetic profile is associated with a higher risk of developing a postoperative thromboembolic complication. Specifically, we examined if the Factor V Leiden (FVL) mutation or the deletion polymorphism of the angiotensin-converting enzyme (ACE) gene increased a patient's risk for postoperative thromboembolic events. The FVL mutation has been associated with an increased risk of idiopathic thromboembolism and the deletion polymorphism of the ACE gene has been associated with increased vascular tone, attenuated fibrinolysis and increased platelet aggregation. METHODS: The presence of these genetic profiles was determined for 38 patients who had a postoperative symptomatic pulmonary embolus or proximal deep venous thrombosis and 241 control patients without thrombosis using molecular biological techniques. RESULTS: The Factor V Leiden mutation was present in none of the 38 experimental patients and in 3% or 8 of the 241 controls (p = 0.26). Similarly there was no difference detected in the distribution of polymorphisms for the ACE gene with the deletion-deletion genotype present in 36% or 13 of the 38 experimental patients and in 31% or 74 of the 241 controls (p = 0.32). CONCLUSIONS: Our results suggest that neither of these potentially hypercoaguable states are associated with an increased risk of symptomatic thromboembolic events following total hip or knee arthroplasty in patients receiving pharmacological thromboprophylaxis.

Journal Article↗

Frequency and timing of clinical venous thromboembolism after major joint surgery.

Over a 13-year period we studied all patients who underwent major hip and knee surgery and were diagnosed with objectively confirmed symptomatic venous thromboembolism, either deep venous thrombosis or non-fatal pulmonary embolism, within six months after surgery. Low-molecular-weight heparin had been given while the patients were in hospital. There were 5607 patients. The cumulative incidence of symptomatic venous thromboembolism was 2.7% (150 of 5607), of which 1.1% had developed pulmonary embolism, 1.5% had deep venous thrombosis and 0.6% had both. Patients presented with deep venous thrombosis at a median of 24 days and pulmonary embolism at 17 days after surgery for hip fracture. After total hip replacement, deep venous thrombosis and pulmonary embolism occurred at a median of 21 and 34 days respectively. After total knee replacement, the median time to the presentation of deep venous thrombosis and pulmonary embolism was 20 and 12 days respectively. The cumulative risk of venous thromboembolism lasted for up to three months after hip surgery and for one month after total knee replacement. Venous thromboembolism was diagnosed after discharge from hospital in 70% of patients who developed this complication. Despite hospital-based thromboprophylaxis, most cases of clinical venous thromboembolism occur after discharge and at different times according to the operation performed.

Aged↗

A cost-effectiveness analysis of fondaparinux sodium compared with enoxaparin sodium as prophylaxis against venous thromboembolism: use in patients undergoing major orthopaedic surgery.

OBJECTIVE: To determine the cost effectiveness of fondaparinux sodium compared with enoxaparin sodium for prophylaxis against venous thromboembolism in patients undergoing major orthopaedic surgery. METHODS: Using a cohort simulation model, two primary analyses were conducted from the perspective of the US healthcare payer. Probabilities for a trial-based analysis were obtained from patients participating in the fondaparinux clinical trial programme supplemented with data from published literature. Probabilities for a label-based analysis were estimated for a hypothetical cohort of US patients receiving either fondaparinux or enoxaparin as recommended by US FDA-approved labelling. Resource use and costs were obtained from large US healthcare databases. Outcome measures were rates of symptomatic thromboembolic events and healthcare costs. Costs were in 2003 values. RESULTS: In the trial-based analysis, fondaparinux was estimated to prevent 15.1 symptomatic venous thromboembolic events (per 1,000 patients) at 3 months for patients undergoing major orthopaedic surgery compared with enoxaparin. The cost savings (per patient) of using fondaparinux over enoxaparin are US 61 dollars at 30 days, US 89 dollars at 3 months, and US 155 dollars at 5 years. In the label-based analysis, fondaparinux was estimated to prevent 17.8 venous thromboembolic events (per 1,000 patients) at 3 months compared with enoxaparin, producing savings per patient of US 25 dollars at discharge, US 112 dollars over 1 month, US 141 dollars over 3 months and US 234 dollars over 5 years. Results remain robust to clinically plausible variation in input parameters and assumptions. CONCLUSION: Our model suggests that fondaparinux, when compared with the current standard regimen of enoxaparin for prophylaxis of venous thromboembolism in major orthopaedic surgery, improves outcomes and is cost saving from a US healthcare-payer perspective over the broad range of assumptions evaluated.

Aged↗

Towards evidence-based guidelines for the prevention of venous thromboembolism: systematic reviews of mechanical methods, oral anticoagulation, dextran and regional anaesthesia as thromboprophylaxis.

OBJECTIVES: To assess the benefits in terms of reductions in the risks of deep vein thrombosis (DVT) and of pulmonary embolism (PE), and hazards in terms of major bleeding, of: (i) mechanical compression; (ii) oral anticoagulants; (iii) dextran; and (iv) regional anaesthesia (as an alternative to general anaesthesia) in surgical and medical patients. DATA SOURCES: Electronic databases, search of Antithrombotic Trialists' Collaboration database, contact with trialists and manufacturers. REVIEW METHODS: All trials identified as fitting the selection criteria were independently assessed. The primary outcomes were DVT, PE and major bleeding events, and proximal venous thrombosis (PVT) and fatal PE were secondary outcomes. Trials were subdivided into those that had assessed a method as the only means of thromboprophylaxis ('monotherapy') and those that had assessed the effects of adding a method to another form of thromboprophylaxis ('adjunctive therapy'). RESULTS: Mechanical compression methods reduced the risk of DVT by about two-thirds when used as monotherapy and by about half when added to a pharmacological method. These benefits were similar irrespective of the particular method used (graduated compression stockings, intermittent pneumatic compression or footpumps) and were similar in each of the surgical groups studied. Mechanical methods reduced the risk of PVT by about half and the risk of PE by two-fifths. Oral anticoagulants, when used as monotherapy, reduced the risk of DVT and of PVT by about half, and this protective effect appeared similar in each of the surgical groups studied. There was an apparently large four-fifths reduction in the role of PE, but not only was the magnitude of this reduction statistically uncertain, but also pulmonary embolism was reported by a minority of trials, so it may be subject to selection bias. Oral anticoagulant regimens approximately doubled the risk of major bleeding and appeared less effective at preventing DVT than heparin regimens, although were associated with less major bleeding. Dextran reduced the risk of DVT and of PVT by about half, again irrespective of the type of surgery, but too few studies had reported PE to provide reliable estimates of effect on this outcome. Dextran appeared to be less effective at preventing DVT than the heparin regimens studied. Dextran was associated with an increased risk of bleeding, but too few bleeds had occurred for the size of this excess risk to be estimated reliably. Compared with general anaesthesia, regional anaesthesia reduced the risk of DVT by about half, and this benefit appeared similar in each of the surgical settings studied. Regional anaesthesia was associated with less major bleeding than general anaesthesia. CONCLUSIONS: In the absence of a clear contraindication (such as severe peripheral arterial disease), patients undergoing a surgical procedure would be expected to derive net benefit from a mechanical compression method of thromboprophylaxis (such as graduated compression stockings), irrespective of their absolute risk of venous thromboembolism. Patients who are considered to be at particularly high risk of venous thromboembolism may also benefit from a pharmacological thromboprophylactic agent, but since oral anticoagulant and dextran regimens appear less effective at preventing DVT than standard low-dose unfractionated heparin or low molecular weight heparin regimens, they may be less suitable for patients at high risk of venous thromboembolism, even though they are associated with less bleeding. Whenever feasible, the use of regional anaesthesia as an alternative to general anaesthesia may also provide additional protection against venous thromboembolism. There is little information on the prevention of venous thromboembolism among high-risk medical patients (such as those with stroke), so further randomised trials in this area would be helpful.

Administration, Oral↗

Residual venous thrombosis as a predictive factor of recurrent venous thromboembolism.

BACKGROUND: The optimum duration of anticoagulant therapy after an episode of deep venous thrombosis (DVT) is controversial. Contributing to the controversy is uncertainty about whether residual venous thrombosis, as assessed by repeated ultrasonography over time, increases the risk for recurrent thromboembolism. OBJECTIVE: To determine the risk for recurrent thromboembolism in patients who have persistent residual thrombosis compared with patients who have early vein recanalization. DESIGN: Prospective cohort study. SETTING: A university hospital in Padua, Italy. PATIENTS: 313 consecutive symptomatic outpatients with proximal DVT who received conventional short-term anticoagulation. MEASUREMENTS: Ultrasonographic assessment of the common femoral and popliteal veins was performed 3 months after acute DVT in all patients and at 6, 12, 24, and 36 months in patients found to have residual venous thrombosis. Veins were considered recanalized if they were 2.0 mm or less in diameter on a single test or 3.0 mm or less in diameter on two consecutive tests. Recurrent thromboembolism was assessed during a 6-year period. RESULTS: The cumulative incidence of normal results on ultrasonography was 38.8% at 6 months, 58.1% at 12 months, 69.3% at 24 months, and 73.8% at 36 months. Of 58 recurrent episodes, 41 occurred while the patient had residual thrombosis. The hazard ratio for recurrent thromboembolism was 2.4 (95% CI, 1.3 to 4.4; P = 0.004) for patients with persistent residual thrombosis versus those with early vein recanalization. CONCLUSIONS: Residual venous thrombosis is an important risk factor for recurrent thromboembolism. Ultrasonographic assessment of residual venous thrombosis may help clinicians modify the duration of anticoagulation in patients with DVT.

Adult↗

Coinheritance of the HR2 haplotype in the factor V gene confers an increased risk of venous thromboembolism to carriers of factor V R506Q (factor V Leiden).

With the aim of establishing whether the HR2 haplotype in factor V affects the risk of venous thromboembolism, a retrospective multicenter cohort study was performed in 810 family members identified through 174 probands who suffered from at least 1 episode of deep vein thrombosis and/or pulmonary embolism and had an inherited defect associated with thrombophilia (antithrombin, protein C, or protein S deficiency; factor V R506Q or prothrombin G20210A). Fifty-eight percent (468/810) of the family members had an inherited defect and 10% (47/468) were symptomatic. The HR2 haplotype was found in association with factor V R506Q more frequently in family members with venous thromboembolism (18%) than in those without (8%). Double heterozygosity for factor V R506Q and HR2 conferred a 3- to 4-fold increase in the relative risk of venous thromboembolism compared with factor V R506Q alone. The median age at first event was lower when the 2 defects were associated (46 v 52 years). No increase in risk of venous thromboembolism could be demonstrated when the HR2 haplotype was associated with inherited thrombophilic defects other than factor V R506Q. Because both factor V R506Q and the HR2 haplotype are very frequent, the effect of their coinheritance on the risk of venous thromboembolism might represent a clinically relevant issue, and screening for HR2 in carriers of factor V R506Q should be considered.

Adolescent↗

Coexistence of factor V Leiden and Factor II A20210 mutations and recurrent venous thromboembolism.

Patients carrying the FV Leiden or the FII A20210 mutation have a high risk of venous thromboembolism. Among 542 patients with a documented diagnosis of deep venous thrombosis in one leg consecutively referred for a thrombophilic work-up, we have retrospectively assessed the rate of objectively documented previous recurrence in carriers of both FV Leiden and FII A20210 mutations. Eighty-two patients had experienced 115 episodes of recurrent venous thromboembolism. The rate of recurrent venous thromboembolism was 29.2% among subjects with and 14.5% in those without deficiencies of natural anticoagulant proteins (p = 0.055), and 24.6% among patients with and 14.0% in those without antiphospholipid antibodies (p = 0.036). The frequency of having a recurrent thromboembolism was 16.2%, 20.0%, and 36.4% among carriers of FV Leiden, FII A20210 mutation, or both gene defects, respectively, and 12.8% in subjects carrying neither mutation (p for trend = 0.004). When adjusted for age, sex, and thrombophilic risk factors, the rate was higher among patients with than in those without deficiencies of natural anticoagulant proteins (OR: 3.0; 95% CI: 1.2-7.5), aPL 2.5 (95% CI: 1.3-4.9), or both FV Leiden and FII A20210 gene mutations (OR 4.8; 95% CI: 1.9-12.2). The rate of previous recurrent venous thromboembolism was significantly higher in subjects carrying both FV Leiden and FII 20210 mutations and was comparable to that observed in subjects with deficiencies of natural anticoagulant proteins or antiphospholipid antibodies.

Adolescent↗