sentences:  Trials in the late 1990s revealed that anticoagulation with warfarin was not required post balloon angioplasty or stent implantation, while intense anti-platelet regimens and changes in procedural technique (most importantly, making sure that the stent was well opposed to the walls of the coronary artery) improved short term and long term outcomes.Many different antiplatelet regimens were evaluated in the 1990s and the turn of the 21st century, with the optimal regimen in an individual patient still being up for debate.With the high use of intracoronary stents during PCI procedures, the focus of treatment changed from procedural success to prevention of recurrence of disease in the treated area (in-stent restenosis).