Not clearly stated. From tables and text it appears that there were 9 randomised trials (461 patients) of efficacy (comparing thrombolytic to heparin), 6 randomised trials (481 patients) comparing efficacy and safety of one thrombolytic versus another.
1. What are the proven advantages of thrombolytic therapy?
Thrombolytic therapy results in more rapid clot resolution than treatment with heparin alone. Within 5 to 7 days, both treatments produce similar improvements in pulmonary perfusion, as assessed by perfusion scan (Level I and II evidence).
Based on data from a small randomised study, thrombolytic therapy appears to reduce mortality in patients with shock due to massive PE (level II evidence).
In haemodynamically stable patients, thrombolysis has not been proven to reduce mortality or the risk of recurrence of PE (level I and II evidence).
In the subset of patients with normal systemic arterial pressure and right ventricular dysfunction, thrombolytic therapy may decrease both mortality and recurrent thromboembolism (level II and III evidence). Based on one level II study, thrombolytic therapy may enhance the resolution of small peripheral emboli and improve the hemodynamic response to exercise.
2. How do available thrombolytic agents compare with regard to efficacy and safety?
The three thrombolytic agents appear to be equally effective and safe when equivalent doses are delivered at the same rate over a short period of time (level II evidence).
A 2-hour infusion of rt-PA results in more rapid clot lysis when compared with the 12 or 24-hour regimens of UK and SK (level II evidence).
3. Should thrombolytic therapy be administered systemically or locally?
The limited available data do not support the use of intrapulmonary thrombolytic therapy (level II and V evidence).
4. What is the role of bolus thrombolytic therapy?
Bolus dose rt-PA therapy is not safer or more effective that the approved 2-hour regimen (level II evidence).
5. What is the optimum time window for PE thrombolysis?
Thrombolytic therapy is most effective when administered soon after PE but benefit may extend up to 14 days after symptom onset. (Level I and II evidence).
6. What are the complications of thrombolytic therapy?
Thrombolytic therapy is accompanied by a significantly greater risk of major haemorrhage than is treatment with heparin alone. There is also a small but clinically important risk of intracranial hemorrhage. (Level I and II evidence).
7. What are the indications for thrombolytic therapy of PE?
Patients with hypotension or other signs of systemic hypoperfusion caused by PE should be treated with thrombolytic therapy (level II evidence).
Additional information is needed to determine whether right ventricular dysfunction and/or large clot burden are, by themselves, indications for PE thrombolysis.