Relationship of plasminogen activator inhibitor-1 levels following thrombolytic therapy with rt-PA as compared to streptokinase and patency of infarct related coronary artery

Background Type 1 plasminogen activator inhibitor (PAI-1) is considered to be risk factor for acute myocardial infarction (AMI). A rebound of circulat ing PAI-1 has been reported after rt-PA administration. We investigated the relationships between PAI-1 levels before and after thrombolytic therapy w ith streptokinase (SK) as compared to rt-PA and the patency of infarct-rela ted arteries. Methods and Results: Fifty five consecutive patients with acu te MI were randomized to streptokinase or rt-PA. The plasma PAI-1 levels we re studied before and serially within 24 h after thrombolytic administratio n. Vessel patency was assessed by an angiogram at 5 +/- 1 days. The PAI-1 l evels increased significantly with both rt-PA and SK as shown by the levels obtained from a control group of 10 patients treated with coronary angiopl asty alone. However, the area under the PAI-1 curve was significantly highe r with SK than with rt-PA (p < 0.01) and the plasma PAI-1 levels peaked lat er with SK than with rt-PA (18 h versus 3 h respectively). Conversely to PA I-1 levels on admission, the PAI-1 levels after thrombolysis were related t o vessel patency. Plasma PAI-1 levels 6 and 18 h after SK therapy and the a rea under the PAI-1 curve were significantly higher in patients with occlud ed arteries (p < 0.002, p < 0.04 and p < 0.05 respectively). The same tende ncy was observed in the t-PA group without reaching significance. Conclusio ns: This study showed that the PAI-1 level increase is more pronounced afte r SK treatment than after t-PA treatment. There is a relationship between i ncreased PAI-1 levels after thrombolytic therapy and poor patency. Therapeu tic approaches aimed at quenching PAI-1 activity after thrombolysis might b e of interest to improve the efficacy of thrombolytic therapy for acute myo cardial infarction.