- Unfractionated heparin is the traditional treatment of choice for patients presenting with submassive pulmonary embolism. However, newer low-molecular-weight heparins have been developed and tested in several clinical trials in the last 2 decades because of the many limitations of unfractionated heparin. The pharmacologic properties of the low-molecular-weight heparins allow them to be administered subcutaneously in fixed, weight-adjusted doses without need for laboratory monitoring. Different studies have recently proved their efficacy in the treatment of patients with deep vein thrombosis. Because there is good evidence that deep vein thrombosis and pulmonary embolism are 2 expressions of a single disease, the use of low-molecular-weight heparins has been extended to patients presenting with clinically stable pulmonary embolism. In particular, the results of 2 important clinical trials, the Columbus and the Thésée, have conclusively proved that the low-molecular-weight heparins are as safe and effective as unfractionated heparin. In some centers, approximately 80% of patients with deep vein thrombosis are treated at home. This suggests that carefully selected patients with clinically stable pulmonary embolism can receive home treatment with low-molecular-weight heparins.