Coagulation Inhibition and Development of Myocardial Damage in ST-Elevation Myocardial Infarction

University dissertation from Uppsala : Acta Universitatis Upsaliensis

Abstract: In 101 patients with ST-elevation myocardial infarction treated with streptokinase the additional effects of lmw-heparin (dalteparin) were investigated. The prognostic value of troponin-T (TnT) was elucidated and the development of myocardial damage was investigated with Positron Emission Tomography (PET).Dalteparin tended to provide a higher rate of TIMI grade 3 flow in the infarct-related artery at 24 h compared to placebo. In patients with signs of early reperfusion there was a higher rate of TIMI grade 3 flow in the dalteparin group compared to placebo. There were significantly fewer patients with ischemic episodes at 6-24 h in the dalteparin compared to placebo group.The increase in coagulation activity was attenuated in the dalteparin group. There was a tendency to more ischemic episodes and lower frequency of TIMI grade 3 flow in patients with persistent elevation of coagulation activity at 18 h. Among deceased patients the coagulation activity was significantly higher than in survivors. The association between elevated TnT on admission and long-term mortality might be explained by longer delay, episodes of chest pain during the last 24 h, less non-invasive signs of reperfusion at 90 minutes, and lower patency in the infarct-related artery at 24 h. Eight patients were investigated with PET at 3h, 24 h and after 3 weeks. PET outlines the infarct region with reduced perfusion and metabolism. The oxidative metabolism in the infarct region at 3 h correlated with the water-Perfusable Tissue Fraction (PTF) and its improvement over time.Dalteparin seems to improve maintenance of coronary patency, which can be explained by attenuation of the increased coagulation activity. Elevated TnT level on admission is associated with a worse outcome, which can partly be explained by less successful fibrinolytic treatment. PET investigations might to be a useful method in future trials evaluating new agents in the treatment of acute myocardial infarction.