RESUMO
OBJECTIVES: The aim of this study was to determine the lowest optimal tissue plasminogen activator (tPA) dose and delivery duration using ultrasound-facilitated catheter-directed thrombolysis (USCDT) for the treatment of acute intermediate-risk (submassive) pulmonary embolism. BACKGROUND: Previous trials of USCDT used tPA over 12 to 24 h at doses of 20 to 24 mg for acute pulmonary embolism. METHODS: Hemodynamically stable adults with acute intermediate-risk pulmonary embolism documented by computed tomographic angiography were randomized into this prospective multicenter, parallel-group trial. Patients received treatment with 1 of 4 USCDT regimens. The tPA dose ranged from 4 to 12 mg per lung and infusion duration from 2 to 6 h. The primary efficacy endpoint was reduction in right ventricular-to-left ventricular diameter ratio by computed tomographic angiography. A major secondary endpoint was embolic burden by refined modified Miller score, measured on computed tomographic angiography 48 h after initiation of USCDT. RESULTS: One hundred one patients were randomized, and improvements in right ventricular-to-left ventricular diameter ratio were as follows: arm 1 (4 mg/lung/2 h), 0.40 (24%; p = 0.0001); arm 2 (4 mg/lung/4 h), 0.35 (22.6%; p = 0.0001); arm 3 (6 mg/lung/6 h), 0.42 (26.3%; p = 0.0001); and arm 4 (12 mg/lung/6 h), 0.48 (25.5%; p = 0.0001). Improvement in refined modified Miller score was also seen in all groups. Four patients experienced major bleeding (4%). Of 2 intracranial hemorrhage events, 1 was attributed to tPA delivered by USCDT. CONCLUSIONS: Treatment with USCDT using a shorter delivery duration and lower-dose tPA was associated with improved right ventricular function and reduced clot burden compared with baseline. The major bleeding rate was low, but 1 intracranial hemorrhage event due to tPA delivered by USCDT did occur.
