The purpose of this study is to compare vascular healing of the stented segment after deployment of titanium-nitride-oxide coated cobalt-chromium OPTIMAX™ bio-active stent (BAS) and SYNERGY™ everolimus-eluting stent (EES) in patients with acute coronary syndromes requiring percutaneous coronary intervention.

Patients treated with BAS will be treated with DAPT for at least 4 weeks after the procedure followed by aspirin alone, while patients in the EES group will be treated with DAPT, at least for 6 months post procedure. In addition, this study will collect initial information about the safety and effectiveness of the BAS in comparison with EES group at 30 days, 6 months, and 12 months.

OPTIMAX-OCT is a prospective, randomized (1:1), study that will be conducted at 2-3 sites (Finland, Belgium) to evaluate OPTIMAX-BAS vascular healing patterns and thrombus formation with OCT at one (Study A) and six (Study B) month after stent implantation in comparison with SYNERGY-EES. Patients receiving BAS will receive dual antiplatelet treatment (DAPT) for at least four weeks followed by aspirin, while patients implanted with EES, will receive DAPT for at least 6 months followed by aspirin.

Patients will be randomized to study A and B as follow:

Study A: OPTIMAX-BAS (n=25) versus SYNERGY-EES (n=25). First 50 patients will be randomized to study A. OCT at 1 month follow up.

Study B: OPTIMAX-BAS (n=30) versus SYNERGY-EES (n=30) Following 60 patients will be randomized to study B. OCT at 6 months follow up.

Randomization is used at the time of recruitment with sealed envelopes. Patients will be randomized in 1:1 fashion. First 50 patients are randomized in study A and following 60 patients in study B. Patients in study A will have OCT follow up at 1 month after index procedure and patients in study B will have OCT at 6 months.

OCT analyses will be performed blinded to patient's characteristics as well as the type of the stent used.

Two (2-3) investigational sites:

• Cardiovascular Center Aalst, Aalst, Belgium
• Heart Center, Satakunta Central Hospital, Pori, Finland

Inclusion Criteria:

1. Age >18 and <80 years
2. STEMI or NSTEMI (assumed by investigator to be type 1 myocardial infarction, according to universal definitions of MI; EHJ 2007; 28(20):2525-38); or unstable angina (clinical symptoms of chest pain, ecg suggestive of reversible ischemia)
3. Patient is willing to comply with specified follow-up evaluations
4. Patient or legally authorized representative has been informed of the nature of the study, agrees to its provisions and has been provided written informed consent, approved by the appropriate Medical Ethics committee or Institutional Review Board.
5. Single de novo or non-stented restenosis lesion
6. Patients with two-vessel disease may have undergone successful treatment of the non-target vessel with approved devices up to and including the index procedure but must be prior to the index target vessel treatment.
7. Target lesion (maximum 20 mm length by visual estimation) to be covered by a single stent of maximum 23mm length.
8. Reference vessel diameter must be >2.5mm and <4.0mm by visual estimate.
9. The vessel diameter should be measured after pre-dilation procedure and after intracoronary nitroglycerin if vasospasm is suspected.
10. Target lesion >50% and <100% stenosed by visual estimate.

Exclusion Criteria:

1. Impaired renal function (serum creatinine >177micromol/l) or on dialysis
2. Platelet count < 10 e5 cells/mm3
3. Patient has a history of bleeding diathesis or coagulopathy or patients in whom antiplatelet and and/or anticoagulation therapy is contraindicated.
4. Patient has received organ transplant or is on a waiting list for any organ transplant.
5. Patient has a known hypersensitivity or contraindication to aspirin, heparin/bivalirudin, clopidogrel/prasugrel/ticagrelol, cobalt chromium alloy, or contrast agent that cannot be adequately pre-medicated.
6. Patient presents with cardiogenic shock.
7. Any significant medical condition which in the Investigator's opinion may interfere with the patient's optimal participation in the study.
8. Currently participating in another investigational drug or device study.
9. Unprotected left main disease.
10. Ostial target lesions.
11. Chronic total occlusion.
12. Calcified target lesions that cannot be adequately pre-dilated.
13. Target lesion has excessive tortuosity unsuitable for stent delivery and deployment.
14. Target lesion involving bifurcation with a side branch larger than 2.0mm in diameter.
15. A >30% stenosis proximal or distal to the target lesion that cannot be covered with the same stent.
16. Diffuse distal disease.
17. Prior stent in the target vessel.