sentences:  Soon after Andreas Gruentzig began performing percutaneous interventions on individuals with stable coronary artery disease, multiple groups described the use of catheter-delivered streptokinase for the treatment of acute myocardial infarction (heart attack).In the early years of coronary angioplasty, there were a number of serious complications.Abrupt vessel closure after balloon angioplasty occurred in approximately 1% of cases, often necessitating emergency bypass surgery.