Actilyse® in Pulmonary Embolism

Pulmonary embolism occurs when a blood clot formed in the deep veins of the upper or lower extremities (deep vein thrombosis, or DVT) breaks free from the vessel wall and is swept into the pulmonary circulation by de-oxygenated blood returning to the heart. Once lodged in the pulmonary artery, the clot can disrupt, and some times completely stop, normal blood flow. The most extreme cases - massive pulmonary embolism - cause complete circulatory collapse and death within as little as two hours of onset. Half a million people in the U.S. and Europe suffer a pulmonary embolism each year, and up to 30% of those affected die.
The blood clots that cause pulmonary embolism develop after a period of stagnant blood flow and vessel wall injury in persons with a variety of clotting risk factors such as recent surgery, genetics, cancer, pregnancy, obesity, medication use, and immobility. DVT-induced pulmonary embolism also occurs among long-distance air travelers, a phenomenon known as economy- or coach-class syndrome. Sudden or strenuous activity can dislodge the clots, freeing them to migrate to the lungs.
In non-life-threatening cases of pulmonary embolism, where there is no disruption of blood flow or right ventricle dysfunction, anticoagulation therapy with intravenous unfractionated heparin and warfarin is the treatment of choice. This approach is slow-acting, some times requiring several weeks of therapy.
Actilyse® is the thrombolytic agent of choice when treating severe cases of pulmonary embolism, as it is capable of restoring normal hemodynamics within one hour of treatment. It has long been used to treat cases of pulmonary embolism complicated by cardiogenic shock or circulatory collapse requiring resuscitation (collectively referred to as hemodynamic instability). In these patients, fast, immediate, thrombolytic therapy is needed, as death is an impending reality. There is a risk of bleeding complications and intracranial haemorrhage, but the potential benefits of thrombolytic therapy in this population far outweigh the risks.
Recently, massive pulmonary embolism patients who are hemodynamically stable but suffer right ventricular dysfunction - a condition known as submassive pulmonary embolism - were identified as another group that can benefit from Actilyse®. In the largest pulmonary embolism trial ever conducted (n=256), Actilyse®, given with unfractionated heparin, significantly reduced the composite endpoint of death and need for additional therapy as compared to unfractionated heparin alone (11% versus 24.6%, p=0.0058).

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