Stent coverage and neo-intimal growth can be evaluated in-detail by intracoronary optical coherence tomography (OCT), which is a catheter-based imaging technique. It is performed as part of the PCI procedure. OCT is the optical analogue of intravascular ultrasound (IVUS), except that it can provide much higher resolution of coronary cross sectional images than IVUS. The LightLab C7XR OCT system (Frequency Domain OCT) used in this Hospital has obtained full CE Mark, approved by the US FDA, and approved for clinical use in Hong Kong. It has been shown to be safe in clinical settings and has been used in over 300 patients without complication at Queen Mary Hospital.

In this study, stent coverage and neo-intimal growth between zotarolimus-eluting stents (ZES) and biolimus-eluting stents (BES) will be compared by using OCT at 9 month and specific post-intervention re-study intervals.

The investigators objective is to investigate the clinical impact and OCT difference on early stent healing and late lumen loss between the two new-generation limus-eluting-stents - Resolute Integrity and Biomatrix, which differ in stent design, eluting drug and coating polymer.

This is a prospective, randomised, assessor-blinded, single centre study. Patients with symptomatic coronary artery diseases in 2 or 3 coronary vessels requiring PCI are eligible for the study. PCI will be performed in the usual manner to all the study lesions in the same procedure. In a randomized fashion, each patient will have one artery with critical disease(s) treated by the Resolute Integrity Stent(s) and the other artery treated by the Biomatrix Stent(s).

Baseline OCT data will be obtained right after stenting. The remaining coronary artery, if diseased and required PCI treatment, will be treated during the angiographic and OCT follow-up as a staged procedure. Patients will be randomly assigned into 5 groups with equal number, receiving a follow-up coronary angiogram with OCT from 2, 3, 4, 5 and 6 months interval post-intervention. Each patient will serve as his/her own control comparing the 2 types of stents. At 9-month post-intervention, all patients will receive a second follow-up coronary angiogram with OCT. All OCT data analyses will be performed in a blinded fashion by a core laboratory. Phone follow up will be carried out for cardiac events at 1 year and 2 year of post intervention.

Inclusion Criteria:

• Patient aged 18-85 years old
• Patient with symptomatic coronary artery diseases involving two or more vessels requiring percutaneous coronary intervention

Exclusion Criteria:

• Patient who is unable to give consent
• Patient in acute myocardial infarction or unstable angina
• Patient who is hemodynamically unstable
• Patient who is allergic to contrast agents
• Patient who is allergic to anti-platelet agents
• Patient who is allergic to zotarolimus
• Patient who is allergic to biolimus
• Patient who is pregnant
• Patient who has planned surgery in the following 12 months after percutaneous coronary intervention
• Left main coronary lesion
• Bifurcation lesion
• Chronic total occlusion lesion
• Coronary vessel size smaller than 2.5mm
• Coronary lesion longer than 38mm in length