Pulmonary embolism: Current treatment options

Abstract

The initial treatment of patients with acute pulmonary embolism has traditionally involved unfractionated heparin. Given the more predictable pharmacodynamic and pharmacokinetic properties of low molecular weight heparins, their simpler (fixed) dosing regimens, and few or no laboratory monitoring requirements, low molecular weight heparins are gradually replacing heparin for the initial treatment of most patients diagnosed with acute pulmonary embolism, except in very obese patients or patients with renal failure. Only selected patients with massive, life-threatening pulmonary embolism should be managed with intravenously administered thrombolytic drugs, surgical embolectomy, or catheter-based embolectomy. Likewise, inferior vena caval filter should be considered only in patients with an absolute contraindication to, or a documented failure of, anticoagulant therapy. New anticoagulants, such as ximelagatran, an oral direct thrombin inhibitor, or fondaparinux and idraparinux, selective factor X(a) inhibitors with an almost complete bioavailability after subcutaneous injection are promising alternatives, but these drugs have yet to find a place in the initial treatment of pulmonary embolism in standard day-to-day clinical practice. Long-term anticoagulation treatment is still provided by antivitamin K antagonists (eg, warfarin), which unfortunately have a narrow therapeutic window. Consequently, time-consuming monitoring is required to ensure the therapeutic anticoagulant effect. A target International Normalized Ratio (INR) of 2.5 (INR range: 2.0 to 3.0) is recommended for warfarin therapy. This treatment should be continued for at least 3 months for patients with a first episode of pulmonary embolism secondary to a transient (reversible) risk factor, or up to 6 to 12 months for patients with a first episode of idiopathic pulmonary embolism.