The purpose of the trial is to directly compare the Cobalt Chromium platform everolimus-eluting stent, Xience Prime™, with the Platinum Chromium platform everolimus-eluting stent, Promus Element™, in relation to stent scaffolding shape, position with the heart blood vessel and extent of tissue coverage (at 6 months) using optical coherence tomography.

Hypotheses:

1. The alloy composition and strut design of a drug-eluting stent has a direct bearing on stent apposition measured using OCT.
2. Stent design and alloy composition have a direct influence on radial support and scaffold shrinkage.

Inclusion Criteria:

1. Age ≥ 18 years
2. Symptomatic coronary artery disease including patients with chronic stable angina, silent ischemia, and acute coronary syndromes including non-ST elevation myocardial infarction
3. Presence of one or more coronary artery stenosis > 50% in a native coronary artery with a reference diameter ranging from 2.25 to 4.25 mm which can be covered with one or multiple stents
4. No limitation to the number of treated lesions or number of vessels according to the randomization group
5. De-novo native coronary disease with complex lesions involving: Bifurcations, chronic occlusions > 3 months, lesions > 20mm in length or moderately/heavily calcified lesions of any length

Exclusion Criteria:

1. Known intolerance to aspirin, clopidogrel, heparin, cobalt chromium, platinum chromium, everolimus, contrast material
2. Acute ST-segment elevation myocardial infarction
3. Type A lesion including vessel angulation <45 degrees
4. Bypass graft
5. Inability to provide informed consent
6. Pregnancy
7. Planned surgery within 12 months of PCI unless dual antiplatelet therapy is maintained throughout the peri-surgical period
8. Left ventricular ejection fraction < 25%
9. Serum creatinine > 180mmol/L