sentences:  Post-procedure bleeding was also an issue, due to the intense combination of anticoagulation and anti-platelet agents used to prevent stent thrombosis.Stent technology improved rapidly, and in 1989 the Palmaz-Schatz balloon-expandable intracoronary stent was developed.Initial results with the Palmaz-Schatz stents were excellent when compared to balloon angioplasty, with a significantly lower incidence of abrupt closure and peri-procedure heart attack.