Thus, TIMI Open Label Phase studies were initiated in 1985, with the aim of establishing the safety and efficacy of the 'new' intravenous rt-PA. As in Phase I, the endpoint was lysis of coronary thrombus within 90 minutes of the initiation of treatment in patients with documented total occlusion of the infarct-related coronary artery. Additional goals of the study were to determine reocclusion rates of infarct-related arteries at 18-48 hours, as well as to determine the efficacy of PTCA to maintain perfusion in infarct-related arteries and prevention of recurrent myocardial infarction. The TIMI Open Label Phase studies determined that optimal coronary recanalization and maintenance of reperfusion occurred with 150 mg of 'new' rt-PA infused over six hours. However, subsequent hemorrhagic complications observed with 150 mg rt-PA necessitated a change in the dose of rt-PA to 100 mg.