• Primary endpoint: Numerical in-stent acute lumen gain in mm [ Time Frame: At the end of the index procedure ]
  The main angiographic endpoint will be in-stent acute lumen gain defined as minimal lumen diameter (MLD) in stent at the end of the index procedure minus baseline MLD.
• Co-primary OCT endpoint: Ratio of stent expansion index (SEI) [ Time Frame: At the end of the index procedure ]
  The main OCT endpoint will be stent expansion index (SEI), defined as minimum stent area divided by mean reference area in optical coherence tomography (OCT) quantitative analysis at the end of the index procedure

• Numerical in-stent late lumen loss at 9 month follow-up angiography in mm [ Time Frame: 9 months follow-up ]
  In-stent late lumen loss at 9 month follow-up angiography defined as the difference between the postprocedure in-stent minimal lumen diameter (MLD)and the in-stent MLD at 9-month followup angiography will be adopted as a co-primary endpoint.
• Rate of angiographic success in percent [ Time Frame: Peri-procedural ]
  'Angiographic Success' defined as successful stent delivery and expansion with attainment of < 20% in-stent residual stenosis of the target lesion in the presence of TIMI 3 flow.
• Rate of strategy success in percent [ Time Frame: Peri-procedural ]
  'Strategy Success' defined as successful stent delivery and expansion with attainment of < 20% in-stent residual stenosis of the target lesion in the presence of TIMI 3 flow without stent failure.
• Rate of target vessel failure in percent [ Time Frame: 9 months, 1 and 2 years follow-up ]
  Target vessel failure (TVF) defined as a composite of cardiac death, target vessel related myocardial infarction and clinically driven target vessel revascularization at 9 months, 1 and 2 years.
• Rate of in-segment binary restenosis at 9 months in percent [ Time Frame: 9 months follow-up ]
  In-segment binary restenosis at 9 months
• Rate of stent thrombosis in percent [ Time Frame: 9 months, 1 and 2 years follow-up ]
  Stent thrombosis
• Rate of peri-procedural myocardial infarction in percent [ Time Frame: Peri-procedural ]
  Peri-procedural myocardial infarction
• Rate of vessel perforation in percent [ Time Frame: Peri-procedural ]
  Rate of vessel perforation
• Numerical procedural duration in min [ Time Frame: Peri-procedural ]
  Procedural duration
• Numerical contrast dye amount in ml [ Time Frame: Peri-procedural ]
  Procedural contrast dye amount

Inclusion Criteria:

Clinical inclusion criteria

1. Age above 18 years and consentable
2. Angiographically proven coronary artery disease
3. Anginal symptoms and/or reproducible ischemia in the target area by ECG, functional stress testing or fractional flow reserve
4. Written informed consent

Angiographic inclusion criteria

1. De-novo lesion in a native coronary artery
2. Target reference vessel diameter between 2.25 and 4.0 mm by visual estimation
3. Luminal diameter reduction of 50-100% by visual estimation
4. Severe calcification of the target lesion (for definition see appendix)

Exclusion Criteria:

Clinical exclusion criteria

1. Myocardial infarction (within 1 week)
2. Decompensated heart failure
3. Limited long term prognosis due to other conditions

Angiographic exclusion criteria

1. Target lesion is in a coronary artery bypass graft
2. Target lesion is an in-stent restenosis
3. Target vessel thrombus