Systemic thrombolysis effectively and rapidly dissolves clots in the pulmonary vasculature as well as the deep veins, but unlike thrombi in coronary or cerebral arteries, a PE usually does not result in permanent tissue necrosis. Provided that the patient survives the immediate hemodynamic effects of the initial event, therapy with antithrombotics alone (heparin products followed by warfarin) will usually keep further clotting at bay, allowing the body's natural fibrinolytic system to slowly dissolve any existing thromboses. This favorable response to standard anticoagulation in the majority of patients with PE, coupled with the known hemorrhagic risks of systemic thrombolysis, limits the target population for thrombolysis to those patients at high risk for hemodynamic collapse and perhaps those at high risk for developing severe pulmonary hypertension, which occurs over the course of months to years in about 4% of patients after an index PE, particularly those with a large thrombus burden.1 The precise indications for systemic thrombolysis, however, remains uncertain and debated.
Brotman DJ, Streiff MB. Thrombolytic Therapy and Mortality in Patients With Acute Pulmonary Embolism—Invited Commentary. Arch Intern Med. 2008;168(20):2191–2192. doi:10.1001/archinte.168.20.2191