Delayed neointimal healing after drug-eluting stent implantation: seeing is believing

Abstract

Ever since its introduction in 1977, the long-term benefit of percutaneous coronary intervention has been limited by the phenomenon of restenosis, i.e. recurrence of significant stenosis at the site of intervention. Whereas, after plain balloon angioplasty, restenosis is for roughly two-thirds due to negative vessel wall remodelling, the late lumen loss after stent implantation is virtually exclusively caused by neointimal hyperplasia, a proliferation of smooth muscle cells with deposition of abundant extracellular matrix. Over the last years, a multitude of anti-proliferative drugs have been tested, several of which have been found effective in inhibiting this neointimal hyperplasia when locally delivered from a polymer-encapsulated stent. The two compounds with the largest clinical experience are paclitaxel and sirolimus, a cytostatic macrocyclic lactone with both anti-inflammatory and anti-proliferative properties. Although the efficacy of these drug-eluting stents (DES) in preventing restenosis has been well established over the last years, recently, concerns have been raised about a possibly increased incidence of late stent thrombosis (more than 6 months after stent implantation) when compared with the very low incidence of late stent thrombosis after implantation of bare metal coronary stents (BMS). At the annual congress of the American College of Cardiology in March 2006, Matthias E. Pfisterer presented a new analysis of the Basel Stent Cost Effectiveness Trial (BASKET), a randomized study that compared BMS and DES. This new analysis, known as Late Clinical Events Related to Late Stent Thrombosis After Stopping Clopidogrel (BASKET-LATE), was performed to determine the risk of late stent thrombosis after discontinuation of clopidogrel and focused on 746 patients from the BASKET study who experienced no cardiac complications within the first 6 months of stent implantation and were advised to discontinue clopidogrel at that time. The investigators continued to follow-up with these patients for another 12 months, in order to determine the … Corresponding author. Tel: +32 16 344 235. E-mail address : walter.desmet{at}uz.kuleuven.ac.be