Thrombolysis for pulmonary embolism: Past, present and future.

Patients with high-risk pulmonary embolism (PE), i.e. those with shock or hypotension at presentation, are at high risk of in-hospital death, particularly during the first hours after admission. A meta-analysis of trials which included haemodynamically compromised patients indicated that thrombolytic treatment significantly reduces the rate of in-hospital death or PE recurrence. Therefore, thrombolysis should be administered to patients with high-risk PE unless there are absolute contraindications to its use. Uncontrolled data further suggest that thrombolysis may be a safe and effective alternative to surgery in patients with PE and free-floating thrombi in the right heart. On the other hand, normotensive patients generally have a favourable short-term prognosis if heparin anticoagulation is instituted promptly, and they are thus considered to have non-high-risk PE. Generally, the bleeding risk of thrombolysis appears to outweigh the clinical benefits of this treatment in patients without haemodynamic compromise. However, within the group of normotensive patients with PE, some may have evidence of right ventricular dysfunction on echocardiography or computed tomography, or of myocardial injury based on elevated cardiac biomarkers (troponin I or T, heart-type fatty acid-binding protein). These patients have an intermediate risk of an adverse outcome in the acute phase of PE. Existing data suggest that selected patients with intermediate-risk PE may benefit from early thrombolytic treatment, particularly if they have a low bleeding risk. However, controversy will continue to surround the optimal treatment for this group until the results of a large ongoing thrombolysis trial are available in a few years.