Peroperative anticoagulation with antithrombin or heparin in infrainguinal bypass surgery. Venographic comparison of subcutaneous low-molecular weight heparin with oral anticoagulant therapy in the long-term treatment of deep venous thrombosis. A randomised open-label trial comparing long-term sub-cutaneous low-molecular-weight heparin compared with oral-anticoagulant therapy in the treatment of deep venous thrombosis. Dalteparin for prevention of catheter-related complications in cancer patients with central venous catheters: final results of a double-blind, placebo-controlled phase III trial. Prevention of postoperative deep vein thrombosis in cancer patients. A randomized trial with low molecular weight heparin (CY 216). Long-term treatment of deep venous thrombosis with a low molecular weight heparin (tinzaparin): a prospective randomized trial. Self-managed long-term low-molecular-weight heparin therapy: the balance of benefits and harms. Enoxaparin for the prevention of venous thromboembolism associated with central vein catheter: a double-blind, placebo-controlled, randomized study in cancer patients. Prevention of catheter-related venous thrombosis with nadroparin in patients receiving chemotherapy for hematologic malignancies: a randomized, placebo-controlled study.
Patients suffering from atherosclerosis may have a hypercoagulable state which is further aggravated by surgery. Thrombin, a central enzyme in the coagulation process, cleaves fibrinogen to fibrin. Therefore, inhibition of thrombin is an important anticoagulant mechanism. This is accomplished by heparin in concert with antithrombin III (AT), but vessel wall glycosaminoglycans may act as substitutes for heparin and catalyse thrombin inhibition. The present study examines whether administration of AT or heparin is effective as an anticoagulant during infrainguinal bypass surgery. Preoperatively and during surgery the patients had elevated levels of fibrinogen, fibrinopeptide A (FPA) and thrombin-antithrombin (T-AT) complexes. There were higher levels of FPA in the venous outflow from the ischemic leg than in the arterial inflow. Taken together these measurements indicate ongoing coagulation in the operated leg. Administration of heparin decreased FPA levels and prevented intraoperative graft thrombosis, whereas in patients receiving AT, T-AT levels increased but FPA levels were unchanged. In the latter group, intraoperative graft thrombosis occurred in a high proportion. Based on additional case histories in these patients with hypercoagulability, it is suggested that fibrinogen is a risk factor for thromboembolic complications and that a combination of low dose of heparin and AT might be an effective regimen to prevent intraoperative thrombosis with a low risk of haemorrhage. The primary objective of this study was to evaluate with venography the rate of thrombus regression after a fixed dose of low-molecular weight heparin (LMWH) per day for 3 months compared with oral anticoagulant therapy for deep venous thrombosis (DVT). Secondary endpoints were the comparisons of the efficacy and safety of both treatments.
                This study was designed as an open randomized clinical study in a university hospital setting. Of the 165 patients finally enrolled in the study, 85 were assigned LMWH therapy and 80 were assigned oral anticoagulant therapy. In the group randomized to oral anticoagulant therapy, the patients first underwent treatment in the hospital with standard unfractionated heparin and then coumarin for 3 months. Doses were adjusted with laboratory monitoring to maintain the international normalized ratio between 2.0 and 3.0. Patients in the LMWH group were administered subcutaneous injections of fixed doses of 40 mg enoxaparin (4000 anti-Xa units) every 12 hours for 7 days, and after discharge from the hospital, they were administered 40 mg enoxaparin once daily at fixed doses for 3 months without a laboratory control assay. A quantitative venographic score (Marder score) was used to assess the extent of the venous thrombosis, with 0 points indicating no DVT and 40 points indicating total occlusion of all deep veins. The rate of thrombus reduction was defined as the difference in quantitative venographic scores after termination of LMWH or coumarin therapy as compared with the scores obtained on the initial venographic results. The efficacy was defined as the ability to prevent symptomatic extension or recurrence of venous thromboembolism (documented with venograms or serial lung scans). The safety was defined as the occurrence of hemorrhages.
                After 3 months of treatment, the mean Marder score was significantly decreased in both groups in comparison with the baseline score, although the effect of therapy was significantly better after LMWH therapy (49.4% reduction) than after coumarin therapy (24.5% reduction; P <.001). LMWH therapy and male gender were independently associated with an enhanced resolution of the thrombus. A lower frequency of symptomatic recurrent venous thromboembolism was also shown in patients who underwent treatment with LMWH therapy (9.5%) than with oral anticoagulant therapy (23.7%; P <.05), although this difference was entirely a result of recurrence of DVT. Bleeding complications were significantly fewer in the LMWH group than in the coumarin group (1. 1% vs 10%; P <.05). This difference was caused by minor hemorrhages. Coumarin therapy and cancer were independently associated with an enhanced risk of complications. Subcutaneous heparin therapy was well tolerated by all patients.
                The patients who were allocated to undergo enoxaparin therapy had a significantly greater improvement in their quantitative venographic score, a significantly lower recurrence rate of symptomatic venous thromboembolism, and a significantly lower incidence of bleeding than patients who underwent treatment with coumarin. LMWH can be used on an outpatient basis as a safer and more effective alternative to classical oral anticoagulant therapy for the secondary prophylaxis of selected patients with DVT. To evaluate whether low-molecular-weight heparin (LMWH) could be equally (or more) effective than oral anti-vitamin-K agents (AVK) in the long-term treatment of deep venous thrombosis (DVT).
                A randomised, open-label trial.
                In this trial, 241 patients with symptomatic proximal DVT of the lower limbs confirmed by duplex ultrasound scan were included. After initial LMWH, patients received 6 months of treatment with full therapeutic dosage of tinzaparin or acenocoumarol. The primary outcome was the 12-month incidence of symptomatic recurrent venous thrombo-embolism (VTE). Duplex scans were performed at 6 and 12 months.
                During the 12-month period, six patients (5%) of 119 who received LMWH and 13 (10.7%) of 122 who received AVK had recurrent VTE (p=0.11). In patients with cancer, recurrent VTE tended to be lower in the LMWH group (two of 36 [5.5%]) vs. seven of 33 [21.2%]; p=0.06). One major bleeding occurred in the LMWH group and three in the AVK group. Venous re-canalisation increased significantly at 6 months (73.1% vs. 47.5%) and at 12 months (91.5% vs. 69.2%) in the LMWH group.
                Tinzaparin was more effective than AVK in achieving re-canalisation of leg thrombi. Long-term tinzaparin was at least as efficacious and safe as AVK for preventing recurrent VTE, especially in patients with cancer. Cancer patients receiving chemotherapy experience thromboembolic complications associated with the use of long-term indwelling central venous catheters (CVCs). This prospective, double-blind, placebo-controlled, multicenter study evaluated whether prophylactic treatment with a low molecular weight heparin could prevent clinically relevant catheter-related thrombosis.
                Patients with cancer undergoing chemotherapy for at least 12 weeks (n=439) were randomly assigned, in a 2:1 ratio, to receive either dalteparin (5000 IU) or placebo, by subcutaneous injection, once daily for 16 weeks. Patients underwent upper extremity evaluation with either venography or ultrasound at the time of a suspected catheter-related complication (CRC) or upon completion of study medication. The primary end point, as determined by a blinded adjudication committee, was the occurrence of a CRC, defined as the first occurrence of any one of the following: clinically relevant catheter-related thrombosis that was symptomatic or that required anticoagulant or fibrinolytic therapy; catheter-related clinically relevant pulmonary embolism; or catheter obstruction requiring catheter removal.
                There was no significant difference in the frequency of CRCs between the dalteparin arm (3.7%) and the placebo arm (3.4%; P=0.88), corresponding to a relative risk of 1.0883 (95% confidence interval 0.37-3.19). No difference in the time to CRC was observed between the two arms (P=0.83). There was no significant difference between the dalteparin and placebo groups in terms of major bleeding (1 versus 0) or overall safety.
                Dalteparin prophylaxis did not reduce the frequency of thromboembolic complications after CVC implantation in cancer patients. Dalteparin was demonstrated to be safe over 16 weeks of treatment in these patients. Sixty-one consecutive patients were enrolled in a randomized, controlled trial of thromboprophylaxis with a low molecular weight heparin (Seleparina, CY 216) in major abdominal oncological surgery. Thirty patients received 2 x 3,825 anti-Xa international units of CY 216 subcutaneously on the day of surgery followed by a single daily 3,825 anti-Xa international units injection for 7 days; thirty-one patients did not receive any form of prophylaxis. The occurrence of deep vein thrombosis (DVT) was detected by 125I-labelled fibrinogen leg scan. Postoperative DVT developed in 2 patients in the CY 216 group and in 11 patients in the control group (6.8% vs 35.4%, p < 0.01). Although there was a higher postoperative transfusional requirement in the group receiving CY216 (p < 0.05), the total number of patients transfused was similar in the two groups (14 vs 13). On day 1 after surgery, the two patients who later developed DVT in the CY216 group had plasma anti-Xa activity significantly lower (p < 0.01) than the remaining patients. As a good relationship was found between plasma anti-Xa activity and body weight, adoption of a personalized dosage schedule might improve efficacy of CY 216 prophylaxis. Evaluation of the effectiveness and safety of the low molecular weight heparin (LMWH) tinzaparin versus unfractionated heparin (UFH) followed by acenocoumarol in proximal deep venous thrombosis (DVT).
                Prospective, randomized clinical trial.
                Consecutive patients (n=108) with acute leg DVT, confirmed by duplex, were randomized to either tinzaparin alone or UFH and acenocoumarol for 6 months. Patients were evaluated ultrasonographically at entry, 1, 3, 6 and 12 months. Thrombus regression, reflux distribution and the incidence of complications were studied. A cost-analysis, comparing the two treatments, was performed.
                The overall incidence of major events (mortality, DVT recurrence, pulmonary embolism, major bleeding, heparin-induced thrombocytopenia) was significantly different (p=0.035) in favor of tinzaparin (7 versus 17 events). The ultrasonographic clot volume score (an index of recanalization) decreased significantly in both treatment groups. However, tinzaparin produced significantly more extended overall recanalization from 3 months onwards (p<0.02). Thrombus regression was equivalent or in favor of tinzaparin in the different DVT subgroups and venous segments, but the statistical significance varied. Reflux showed non-significant differences overall or in subgroups. A cost-analysis resulted in favor of LMWH.
                A fixed daily dose of tinzaparin for 6 months was at least as effective and safe as UFH and acenocoumarol. Regarding major events and recanalization, there was a significant benefit in favor of tinzaparin. Long-term DVT treatment with tinzaparin could represent an alternative to conventional treatment. A substantial clinical need exists for an alternate to vitamin K antagonists for treating deep vein thrombosis in many patients. Long-term low-molecular-weight heparin (LMWH), body-weight adjusted, avoids anticoagulant monitoring and may be associated with less bleeding. We evaluated the effectiveness and safety of long-term LMWH compared with vitamin K antagonist therapy in a broad spectrum of patients with proximal vein thrombosis.
                We performed a multicenter, randomized, open-label clinical trial using objective outcome measures comparing therapy for 3 months. Outcomes were assessed at 3 and 12 months.
                Of 737 patients, 18 of 369 receiving tinzaparin (4.9%) had recurrent venous thromboembolism at 3 months compared with 21 of 368 (5.7%) receiving usual care (absolute difference, -0.8%, 95% confidence interval -4.1-2.4). Hemorrhagic complications occurred less frequently in the LMWH group largely because of less minor bleeding: 48 of 369 patients (13.0%) versus 73 of 368 patients (19.8%) receiving usual-care anticoagulation (absolute difference -6.8%; P = .011; risk ratio = 0.66). New major bleeding events ceased early (by day 23, P = .034) for patients receiving LMWH but persisted throughout the study treatment interval for patients receiving vitamin K antagonist therapy. No mortality advantage was shown for LMWH.
                Our study shows that LMWH is similar in effectiveness to the usual-care vitamin K antagonist treatment for preventing recurrent venous thromboembolism in a broad spectrum of patients. It causes less harm and enhances the clinicians' therapeutic options for patients with proximal deep vein thrombosis. Our findings reported here suggest the possibility of a broader role for long-term LMWH in selected patients. The extent of venous thromboembolism (VTE) associated with central vein catheters (CVC) in cancer patients remains unclear. The aim of this study was to evaluate the efficacy and safety of the low molecular weight heparin, enoxaparin, in the prevention of VTE.
                In a multicenter, double-blind study, consecutive cancer patients scheduled for CVC insertion were randomly assigned to receive either subcutaneous enoxaparin 40 mg once a day or placebo. Treatment was started 2 hours before CVC insertion and continued for 6 weeks. The primary end points of the study were deep vein thrombosis (DVT), confirmed by venography of the CVC limb performed 6 weeks after randomization, or clinically overt pulmonary embolism, confirmed by objective testing during the study drug administration. Patients were assessed for bleeding complications.
                Three hundred eighty-five patients were randomized, of which 321 (83.4%) underwent venography. A venography was adequate for adjudication in 155 patients in each treatment group. A DVT was observed in 22 patients (14.1%) treated with enoxaparin and in 28 patients (18.0%) treated with placebo, corresponding to a relative risk of 0.78 (95% CI, 0.47 to 1.31). No major bleeding occurred. Five patients (2.6%) in the enoxaparin group and two patients (1.0%) in the placebo group died during the treatment period.
                In this study, no difference in the rate of CVC-related VTE was detected between patients receiving enoxaparin and patients receiving placebo. The dose of enoxaparin used in this study proved to be safe. Clinical trials evaluating higher enoxaparin doses could optimize the efficacy of this agent for this indication. Hemato-oncology patients treated with intensive chemotherapy usually require the placement of a central venous catheter (CVC). CVCs are frequently complicated by catheter-related central venous thrombosis (CVT), which has been associated with an increased risk of pulmonary embolism and catheter-related infection.
                To determine the efficacy and safety of thromboprophylaxis with s.c. low-molecular-weight heparin (nadroparin) administered once daily in a randomized placebo-controlled, double-blind trial in patients with hematologic malignancies.
                Consecutive patients with hematologic malignancies requiring intensive chemotherapy including autologous stem cell transplantation were eligible. The patients were randomized to receive nadroparin 2850 antifactor Xa units once daily or placebo s.c. for 3 weeks. Venography was performed on day 21 after CVC insertion. Secondary outcomes were bleeding and catheter-related infection.
                In total, 113 patients were randomized to nadroparin or placebo, and 87 patients (77%) underwent venography. In total, 11 venographically proven catheter-related CVTs were diagnosed. The frequency of catheter-related CVT was not significantly different between study groups, namely four catheter-related CVTs in the placebo group [9%; 95% CI: 0.002-0.16] vs. seven catheter-related CVTs in the nadroparin group (17%; 95% CI: 0.06-0.28). In addition, no difference in the incidence of catheter-related infection or bleeding was observed between the groups.
                This study showed that the actual risk for catheter-related CVT in patients with hematologic malignancies is lower than suggested in earlier studies in cancer patients. Although prophylactic administration of nadroparin appeared to be safe in this group of patients with a high risk of bleeding, it cannot be recommended for the prevention of catheter-related CVT or catheter-related infection in patients with hematologic malignancies.
We found no statistically significant effect of heparin or VKA on the outcomes of interest. However, the findings did not rule out clinically important benefits and harms. Patients with cancer with CVCs considering anticoagulation should balance the possible benefit of reduced thromboembolic complications with the possible harms and burden of anticoagulants.