Cardiac: Coronary Stents

Abstract

Percutaneous coronary intervention (PCI) with stent placement is the leading technique for nonsurgical myocardial revascularization therapy. Despite a technical success rate of more than 95%, in-stent restenosis remains a major clinical problem. Restenosis rates of up to 46% have been described in patients receiving non-drug-eluting stents.1 Although the incidence of early in-stent restenosis may be significantly reduced when drug-eluting stents are employed, the early detection of restenosis is important to avoid recurrent myocardial ischemia and infarction and thus to improve the long-term prognosis after revascularization therapy. Furthermore, patients who previously underwent PCI often suffer from progression of atherosclerosis at other sites and may therefore require repeated imaging studies for the assessment of arterial patency. Currently conventional catheter coronary angiography remains the reference standard for the assessment of stent patency and overall for the evaluation of coronary artery stenosis. Due to its invasiveness, conventional coronary angiography is associated with rare but potentially serious side effects such as retroperitoneal bleeding, arterial rupture, myocardial infarction or stroke. Therefore, a non-invasive alternative for imaging of the coronary artery system would be highly desirable. Coronary magnetic resonance angiography is of limited value for the assessment of stent patency due to susceptibility artifacts generated by the metallic stent material, which usually obscures the stent lumen. Electron beam computed tomography (EBCT) has been employed for the display of coronary artery stents. However, EBCT does not allow the accurate visualization of the stent lumen and is therefore of limited value for the diagnosis of stent restenosis.2 Compared with EBCT, multi-detector computed tomography (MDCT) allows acquisition of image data with thinner slice thickness and less noise.