The purpose of this study is to use a high-resolution intracoronary imaging modality, called optical coherence tomography (OCT) to examine two different types of coronary artery stents used to treat patients with coronary artery disease.

The development of coronary stents has significantly improved the safety and efficacy of percutaneous coronary intervention (PCI) compared to balloon angioplasty alone. Nevertheless, restenosis is still encountered in 20 to 40% of coronary lesions after implantation of bare metal stents, inferring frequent repeat revascularization procedures with a negative impact on quality of life and health care expenditures. Drug-eluting stents (DES), with their controlled release of therapeutic agents, have significantly reduced the rate of major adverse cardiac events (MACE) following coronary stent implantation, primarily by a reduction in restenosis and target lesion revascularization.

Optical coherence tomography (OCT) is an optical analogue of intravascular ultrasound (IVUS): it uses an infrared light source (wavelength 1310nm) and measures the backscatter of light in a technique similar to conventional ultrasound. With this technique a resolution up to 10μm in-vivo has been reported, a far better level of resolution compared with IVUS. Optical coherence tomography has been used in vivo and has detected early atherosclerotic plaques previously not visualised by IVUS. Segments with strut malapposition and the presence or thickness of neointimal hyperplasia can also be more accurately assessed with OCT compared with IVUS.

The present study will utilize the imaging capabilities of OCT to assess stent strut malapposition and tissue coverage in two different types of DES. The biolimus-eluting stent eludes biolimus from a biodegradable polylactic acid polymer on the abluminal surface of a stainless steel stent. This stent will be compared in a randomized fashion to the permanent polymer based everolimus-eluting coronary stent made of cobalt chromium alloy.

Inclusion Criteria:

• Age ≥ 18 years
• Symptomatic coronary artery disease including patients with chronic stable angina, silent ischemia, and acute coronary syndromes including non-ST elevation myocardial infarction
• Presence of one or more coronary artery stenosis > 50% in a native coronary artery with a reference diameter ranging from 2.25 to 4.0 mm which can be covered with one or multiple stents
• No limitation to the number of treated lesions, number of vessels or lesion length according to the randomization group

Exclusion Criteria:

• Known intolerance to aspirin, clopidogrel, heparin, stainless steel, cobalt chromium, Biolimus, everolimus, contrast material
• Acute ST-segment elevation myocardial infarction
• Bypass graft
• Inability to provide informed consent
• Pregnancy
• Planned surgery within 12 months of PCI unless dual antiplatelet therapy is maintained throughout the peri-surgical period
• Left ventricular ejection fraction < 25%
• Serum creatinine > 180mmol/L