Low molecular weight heparins: current use and indications

Thromboembolic complications are associated with significant morbidity and mortality in postoperative patients. For many years, unfractionated heparin has been used successfully in primary and secondary prophylaxis of these complications. In recent times, however, the usefulness of LMWHs has caught the attention of clinicians because of improved bioavailability, predictable anticoagulation, ease of administration, and the lack of need for monitoring anticoagulation. In clinical situations, LMWHs have been tested and proved to be safe and equipotent or supe rior when compared with unfractionated heparin or warfarin (Table 5). It is clear from clinical trials that LMWHs are superior in primary prophylaxis of DVT in orthopaedic surgical procedures, treatment of unstable angina, and in patients with multiple traumas. LMWHs were also tested and found to be an acceptable alternative to unfractionated heparin in both the primary prophylaxis of DVT in high risk general surgical procedures and in the treatment of patients with DVT and pulmonary embolism. However, the role of LMWHs in ischemic heart diseases, valvular heart diseases, postcoronary angioplasty, and vascular surgery remains to be proved. The major impact of LMWHs would be in allowing clinicians to treat PE and DVT in an outpatient setting, which would directly impact medical economics. LMWHs are associated with similar complications as unfractionated heparin is, but the complications occur less frequently. Currently, the main limitation in using LMWHs in place of unfractionated heparin or warfarin is its cost. However, taking into account the cost incurred by hospitalization and longterm monitoring of anticoagulation in patients treated with unfractionated heparin, certain trials have proved the cost of LMWHs to be the same or less than the cost of unfractionated heparin overall. We envision that LMWHs will be widely used in the future and will bring welcomed change in the treatment of thromboembolic diseases.