MOPETT (2013)

Submassive pulmonary embolism (PE) carries a significant risk of adverse outcomes, including chronic pulmonary hypertension and recurrent VTE. Standard anticoagulation alone may not prevent these complications, leading to interest in thrombolytic therapy. The MOPETT trial investigated whether low-dose thrombolysis could improve long-term outcomes in submassive PE.

This was a randomized controlled trial comparing low-dose alteplase (50 mg over 2 hours) plus anticoagulation versus anticoagulation alone in patients with submassive PE. The study population included patients with acute PE, right ventricular dysfunction on echocardiography, and elevated troponin. The primary endpoint was the composite of recurrent PE or development of pulmonary hypertension at 2 years.

Patients receiving low-dose alteplase had significantly lower rates of recurrent PE or pulmonary hypertension at 2 years (16% vs. 57% in the control group, p<0.001). Specifically, the incidence of pulmonary hypertension was 12% in the alteplase group compared to 43% in the control group (p<0.001). There was no significant difference in major bleeding between the two groups (6% vs. 5%, p=NS).

Low-dose thrombolysis with alteplase in patients with submassive PE significantly reduces the risk of recurrent PE and chronic pulmonary hypertension without increasing major bleeding, suggesting a benefit for select patients.

The study was single-center and relatively small (n=121), which may limit generalizability. The definition of submassive PE relied on echocardiographic RV dysfunction and troponin, which may not capture all relevant risk profiles.