These considerations explain why thrombolysis has not been universally adopted for patients with pulmonary embolism; in many medical centers, lytic therapy is often reserved for patients with massive pulmonary embolism and a significant hemodynamic impairment. Promising results have been obtained with rt-PA in a series of clinical trials reported by Goldhaber et al.
Even more debated is the use of thrombolytic agents for DVT. Presently, heparin is the treatment of choice in patients with objectively confirmed DVT and is effective in most patients. The potential advantages of thrombolytic therapy over heparin treatment include prevention of pulmonary embolism by lysing the source of thrombus in situ, rapid restoration of normal venous circulation with a prompt resolution of symptoms, and prevention or reduction of venous valve damage, which would otherwise result in chronic venous insufficiency. A pooled analysis of 6 randomized trials comparing heparin with streptokinase indicates that in patients treated with streptokinase, important clot lysis was achieved 3.7 times more often than in patients receiving heparin, but with a 2.9 times greater risk of bleeding.