This document discusses the history and evolution of percutaneous coronary intervention (PCI) procedures such as angioplasty and stenting to repair coronary arteries. It covers the initial development of balloon angioplasty, the issues it posed around restenosis and abrupt closure, and how stents helped address these issues but introduced the new problem of in-stent restenosis. Drug-eluting stents were then developed to significantly reduce restenosis rates by preventing cell replication through the local delivery of drugs. The document discusses ongoing research to develop newer stent materials, polymers, drug coatings, and bioabsorbable technologies to continue improving PCI outcomes and safety.