Oral Rapamycin to Reduce Intimal Hyperplasia After Bare Metal Stent Implantation - A Prospective Randomized Intravascular Ultrasound Study

Abstract

Coronary artery disease is a major health problem throughout the world. Important advances in diagnosis and treatment of atherosclerotic disorders have been made over the last five decades. Coronary angiography, introduced by Mason Sones in 1958 has been very effective on expanding the diagnosis and treatment of coronary lesions. The introduction of conventional balloon percutaneous transluminal coronary angioplasty (PTCA) by Andreas Gruntzig in 1977, represented an innovative and quite efficient non surgical treatment of angina pectoris and acute myocardial infarction. This procedure was however frequently complicated by an abrupt vessel closure, coronary dissections and a high incidence of restenosis (up to 40 – 50 % of cases) (Gruntzig et al., 1979). In 1986 the first coronary Wallstent was implanted in Toulouse by Jacques Puel and Ulrich Sigwart (Sigwart et al., 1987) and in 1994 Palmaz-Schatz stents were approved by FDA in the United States. Coronary stents improved the immediate and long-term results of coronary angioplasty, reducing immediate complications of the procedure like coronary dissection and abrupt closure and the incidence of restenosis. However, despite technical advances in stent delivery systems and design the rate of restenosis after stent implantation remained 20-30% especially in the high risk patients subsets (Serruys et al., 1994; Fischman et al., 1994). To overcome the problem of restenosis the drug eluting stents Cypher and Taxus were approved in 2003 and 2004 respectively. The initial studies with these stents demonstrated a marked major advance in reducing restenosis (Bailey, 1997; Serruys et al., 2002). Later studies however confirmed that despite these advances, in the real world, stent thrombosis (acute, subacute and late) and instent restenosis still remain a great clinical challenge (Daemen et al., 2007). The process of restenosis is complex. Restenosis may ensue mainly because of: a) patients-related factors (diabetes, restenosis after PTCA, chronic renal insufficiency, high serum PCR etc), b) vessel factors (chronic occlusion, vessel involved e.g. LAD, SVG etc, vessel 30 mm, bifurcation lesion, ostial lesion), c) procedure factors (post-stent MLD < 3mm, multiple stents, stent underexpansion or malapposition, stent fracture).