<P> 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 . Late restenosis rates with Palmaz - Schatz stents were also significantly improved when compared with balloon angioplasty . However, mortality rates were unchanged compared to balloon angioplasty . While the rates of subacute thrombosis and bleeding complications associated with stent placement were high, by 1999 nearly 85% of all PCI procedures included intracoronary stenting . </P> <P> In recognition of the focused training required by cardiologists to perform percutaneous coronary interventions and the rapid progression in the field of percutaneous coronary interventions, specialized fellowship training in the field of Interventional Cardiology was instituted in 1999 . </P> <P> Through the 1990s and beyond, various incremental improvements were made in balloon and stent technology, as well as newer devices, some of which are still in use today while many more have fallen into disuse . As important as balloon and stent technology had been, it was becoming obvious that the anticoagulation and anti-platelet regimen that individuals received post-intervention was at least as important . 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 . </P> <P> 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). By the late 1990s it was generally acknowledged among cardiologists that the incidence of in - stent restenosis was between 15 and 30%, and possibly higher in certain subgroups of individuals . Stent manufacturers experimented with (and continue to experiment with) a number of chemical agents to prevent the neointimal hyperplasia that is the cause of in - stent restenosis . </P>

When were stents first used in the uk