In a report from the recent Moderate Pulmonary Embolism Treated With Thrombolysis (MOPETT) trial, the investigators described the efficacy of low-dose tissue plasminogen activator in reducing the incidence of pulmonary arterial hypertension at 28-month follow-up in patients with pulmonary embolism. The reported incidence (57%) of pulmonary hypertension in their control group at 28 months is in stark contrast to the previously reported incidence of pulmonary hypertension (<5% at 3 years after pulmonary embolism). Although the high occurrence of pulmonary hypertension could have been due to inadequate anticoagulation during hospitalization and follow-up, the underlying cardiopulmonary diseases might have also contributed to the development of pulmonary hypertension. Although the co-morbid diseases in the 2 groups were reported to be similar, the investigators did not specify the severity of underlying diseases, especially cardiovascular and respiratory diseases, which might independently influence pulmonary arterial pressures and might explain the difference of pulmonary arterial pressures between the 2 groups. Moreover, the different underlying pulmonary conditions (interstitial lung diseases vs obstructive lung diseases) between the 2 groups might also explain the difference in incidence of pulmonary hypertension. Finally, we also wish to know the prevalence of coexistent left ventricular diastolic dysfunction in the study population.