The investigators aim at analyzing the diagnostic accuracy of 320-row CT for coronary stents.

Inclusion Criteria:

• Suspected coronary artery in-stent restenoses based on clinical findings or findings on other noninvasive imaging tests and planned coronary angiography within the next 14 days.
• Able to understand and willing to sign the Informed CF.

Exclusion Criteria:

• Creatinine of above 2.0 mg/dl
• Age below 40 years
• Women of child bearing potential (no hysterectomy, no menopause, or menopause since less than 12 months) must demonstrate a negative pregnancy test performed within 24 hours before CT.
• Resting heart rate above 70 beats per minute and contraindications to beta blockers (e.g. moderate to severe bronchospastic disease, asthma)
• Atrial fibrillation, uncontrolled tachycardia, A-V block II or III degree or other non-sinus rhythms
• Inability to hold the breath for 10 seconds
• Hypotension < 80 mmHg systolic
• Unstable angina pectoris, acute myocardial infarction < 48h
• Continuous therapy with Dipyridamol
• Severe aortic stenosis

Patients who underwent coronary artery stent placement in the past and are clinically indicated to undergo conventional coronary angiography.