CC9287-Ghanem.indd Expanded abstract Citation Ch en Wang, Zh enguo Zhai, Yuanhua Yang, Qi Wu, Zhaozhong Cheng, Lirong Liang, Huaping Dai, Kewu Huang, Weixuan Lu, Zhonghe Zhang, Xiansheng Cheng, Ying H Shen, For the China Venous Th romboembolism (VTE) Study Group: Chest 2010, 137:254–262. Trial regis tration: clinicaltrials.gov; Identifi er: NCT00781378. Background Optimal dosing of recombinant tissue-type plasminogen activator (rt-PA) is important in treating pulmonary thromboembolism (PTE). Methods Objective: Th e aim of this study was to compare the effi cacy and safety of a 50 mg/2 h rt-PA regimen with a 100 mg/2 h rt-PA regimen in patients with acute PTE. Design: A prospective, randomized, open label trial. Setting: A multicenter trial in China. Subjects: 118 patients with acute PTE and either hemo- dynamic instability or massive pulmonary artery obstruction. Intervention: Patients were randomly assigned to receive a treatment regimen of either rt-PA at 50 mg/2 h (n= 65) or 100 mg/2 h (n= 53). Outcomes: Th e effi cacy was determined by observing the improvements of right ventricular dysfunctions (RVDs) on echocardiograms, lung perfusion defects on venti la- tion perfusion lung scans, and pulmonary artery obstruc- tions on CT angiograms. Th e adverse events, including death, bleeding, and PTE recurrence, was also evaluated. Results Progressive improvements in RVDs, lung perfusion defects, and pulmonary artery obstructions were found to be similar in both treatment groups. Th is is true for patients with either hemodynamic instability or massive pulmonary artery obstruction. Th ree (6%) patients in the rt-PA 100 mg/2 h group and one (2%) in the rt-PA 50 mg/2 h group died as the result of either PTE or bleeding. Importantly, the 50 mg/2 h rt-PA regimen resulted in less bleeding tendency than the 100 mg/2 h regimen (3% vs. 10%), especially in patients with a body weight, 65 kg (14.8% vs. 41.2%, P = 0.049). No fatal recur- rent PTE was found in either group.