Enrollment rate too slow to reach anticipated number of participants.

Coronary CT angiography is challenging in patients with more than mildly calcified coronary vessels, because of calcium artefacts that prevents evaluation of the lumen. The purpose of the CCT-PCD-1-study is to evaluate the diagnostic accuracy and image quality in coronary CT angiography using a commercially available CT system equipped with a photon counting detector technology.

Patients referred for cardiac CT and conventional coronary angiography as part of routine preoperative evaluation before Transcatheter Aortic Valve Implantation (TAVI) will be asked for inclusion in the study. This group of patients has generally a coronary artery calcium burden and perform cardiac CT and coronary angiography as part of routine care.

The diagnostic accuracy concerning significant coronary artery stenosis on the preoperative CT will be evaluated with the conventional coronary angiography as reference. Also, CT examination image quality will be evaluated.

Inclusion Criteria:

• Patients referred for cardiac CT AND conventional coronary angiography as part of routine preoperative evaluation.

Exclusion Criteria:

• <65 years old.
• Heart arrhythmia.
• Heart rate >90/min with contraindication against beta blockers.
• Not capable of giving informed consent
• eGFR <30 mL/min/1.73m2

The study population are at least 65 years old with an expected median age of ~80 years. This group of patients has generally a high coronary artery calcium burden which prevents conventional cardiac CT from evaluation of the coronary arteries.

Since cardiac CT and coronary artery angiography is performed as part of routine care in this patient cohort, no extra examinations are needed for the reference measure of the primary outcome.