Low molecular weight heparin in prevention of restenosis after PTCA

Low-molecular-weight heparin in arterial reconstructive surgery: a double-blind, randomized dose-finding trial

Periprocedural and postprocedural anticoagulation during arterial reconstructive surgery (ARS) with intravenous heparin is standard of care. The general use and correct dosage of low-molecular-weight heparin, however, are still under debate. A prospective, randomized, double-blind trial was performed with a parallel group comparison of four dose regimen of a low-molecular-weight heparin, reviparin sodium, in patients undergoing major ARS. Sixty-five patients were randomly allocated to receive twice-daily subcutaneous injections of reviparin, 3500 (group A, n=17), 4200 (group B, n=16), 5950 (group C, n=16), and 7000 (group D, n=16) anti-Xa IU per day. Patients were eligible for the trial if they had angiographically proven peripheral arterial obstructive disease with a planned arterial reconstruction of the infrarenal aorta, iliaca artery, or femoralis artery. Fifty-nine patients completed the trial. The goal was to determine the optimal dose of the low-molecular-weight heparin to achieve a minimum of early vascular events (less than 12%) with a minimum of major bleeding events (less than 10%) during a short-term follow-up of up to 8 postoperative days. There was no reocclusion in the entire population. Patients randomized into the two lower dose groups (A and B), however, experienced a relatively high incidence of restenosis, whereas patients enrolled in group D, receiving the highest dose of reviparin, experienced an unacceptably high rate of bleeding events (all bleeds, 43%; major bleeding, 14.3%). Thus, the optimal dose of reviparin sodium to be administered in patients undergoing major ARS is half the therapeutic dose: 5950 to 6300 anti Xa IU (75-85 anti Xa IU/kg body weight per day). Patients included in group C had no major bleeding event (95% confidence interval, 0% to 6.6%), a significant improvement of the doppler ankle-brachial systolic pressure index (difference of 0.46 +/- 0.29, P=.017), and a higher rate of responders with regard to the puls status measured at the tibialis posterior arteries (66.7%) compared to groups A and B (46.7% and 54.5%, respectively, P=.086). The efficacy and safety of this dosage regimen in comparison to standard of care should be further substantiated in larger trials.

Reviparin: a review of its efficacy in the prevention and treatment of venous thromboembolism

Reviparin (reviparin sodium) is a low molecular weight heparin (LMWH) that catalyses the inactivation of factors Xa and IIa by binding to antithrombin, which ultimately leads to the inhibition of the clotting cascade. It is administered subcutaneously. Reviparin 7,000 to 12,600 anti-XaIU/day was found to be as effective as intravenous unfractionated heparin in preventing the clinical recurrence of acute deep vein thrombosis (DVT) and/or pulmonary embolism in 1 large randomised, multicentre trial (COLUMBUS) and was significantly more effective than intravenous unfractionated heparin in the prevention of recurrent venous thromboembolism in another large randomised, multicentre trial (CORTES). Reviparin has also been compared with unfractionated heparin in children with established DVT. However, the trial was under-powered and no conclusion could be made regarding comparative efficacy. As prophylaxis, reviparin 1,750 anti-XaIU once daily was as effective as unfractionated heparin 5,000IU twice daily in 1,311 patients undergoing abdominal surgery and, in a once daily dosage of 4,200 anti-XaIU, was as effective as subcutaneous enoxaparin sodium 40 mg/day or acenocoumarol in patients undergoing hip replacement surgery. Reviparin 1,750 anti-XaIU also effectively prevented DVT. compared with no treatment, in patients undergoing knee arthroscopy. It was also more effective than placebo in patients with brace immobilisation of the lower extremity. Reviparin was compared with 'standard care' in children with central venous lines. However, the trial was too small to make conclusions regarding its efficacy. Comparative data indicate that reviparin is at least as well tolerated as heparin and enoxaparin sodium. However, in a large (n = 1,279) trial there were significantly fewer major bleeding episodes in patients receiving reviparin than in patients given the oral anticoagulant acenocoumarol. The most commonly reported adverse events in therapeutic trials have been intraoperative blood loss and postoperative bleeding complications such as wound haematoma, bruising and injection site haemorrhage. Reviparin was also well tolerated in 2 studies in children aged < or = 16 years.

CONCLUSION

Reviparin has shown efficacy in the treatment of established DVT and in the prevention of postoperative DVT after moderate and high risk surgery and was as effective as enoxaparin sodium or acenocoumarol in patients undergoing hip replacement surgery. As an effective and well tolerated antithrombotic agent, reviparin is likely to assume a significant role in the treatment and prevention of DVT, as it appears to have a preferable tolerability profile to subcutaneous heparin after moderate risk surgery and is at least as effective as intravenous heparin in the treatment of established DVT.