The primary objective of this study is:

• comparison of a safety and effectiveness of third generation DES (biolimus A9 and everolimus) in patients with STEMI treated by primary PCI with OCT guidance. A rate of 9 month MACE (deaths, myocardial infarction, ischemia driven TLR) will be assessed in both groups.

The secondary outcomes are a comparison of (using OCT):

• number of uncovered stent struts
• number of malapposed stents struts
• in-stent neointimal volume
• in-segment assessment of vessel wall response to DES

The aim of this multicenter, prospective, randomized trial with a core lab analysis is to assess the safety and effectiveness (at 9-month follow-up) of third generation DES (biolimus A9 and everolimus) in patients with evolving STEMI with the OCT guidance (to optimize a stent implantation) A serial OCT analysis will be performed to assess the number of either uncovered or malaposed stents strut and a degree of in-stent neointimal hyperplasia. Furthermore, the in-segment vessel wall response to DES implantation will also be analysed. The goal is to enroll 400 patients (200 in each group) with OCT guidance in 100 patients in each group.

Inclusion Criteria:

1. Acute STEMI within 12 hours from symptoms onset
2. Native coronary disease with a lesion suitable for stenting
3. Vessel size in between 2.5-3.75mm
4. Patient is willing to provide written informed consent
5. Male or female patients between 18-85 years of age

Exclusion Criteria:

1. Significant left main disease
2. Killip class IV
3. Known allergy to aspirin and or clopidogrel/ticlopidine
4. Recent bleeding (<1month)
5. Patient in anticoagulant therapy
6. No suitable coronary anatomy for OCT scan (ostial lesion, very distal or large vessel />3.75mm in diameter/)
7. Pregnancy
8. Severe liver or renal disease (Cr>2.0)
9. Life expectancy < 1 year