Plasminogen activator inhibitor type-1 (part two): role for failure of thrombolytic therapy. PAI-1 resistance as a potential benefit for new fibrinolytic agents.

Rapid and sustained reperfusion of an occluded coronary artery is the goal of thrombolytic therapy in acute myocardial infarction. However, the clot-dissolving efficacy of fibrinolytic agents such as tissue-type plasminogen activator (t-PA) is limited, in vivo, in part by the action of plasminogen activator inhibitor type-1 (PAI-1). A new generation of fibrinolytic agents has been genetically engineered to have greater resistance to PAI-1 inhibition. This article reviews the pathophysiologic role of PAI-1 in failure of thrombolytic therapy and describes the advantages that PAI-1-resistance may confer upon fibrinolytic agents such as TNK-t-PA, the new fibrinolytic agent with the most powerful PAI-1 resistance.