Evaluation of Diagnostic Accuracy, Safety, and Cost-Effectiveness of the Non-Invasive Cardiolens FFR-CT Pro Method to Measure the Fractional Flow Reserve in Diagnostics of Chronic Coronary Syndromes Versus the Standard Diagnostic Modalities. A Multicentre Post-marketing Trial of a Class 2a Medical Device, Cardiolens FFR-CT Pro - Software for Non-invasive Determination of Haemodynamic Parameters in Coronary Arteries.

Stage 1 After a patient declares their consent, a doctor or another member of the study team trained by the sponsor will perform procedures in the following order: * Define the unique patient ID to be recorded in the CRF with the patient's demographic data * Assess the quality of CCTA imaging data (DICOM) according to guidelines agreed upon with the sponsor and record the number and location of the significant (≥50%) stenosis sites in the CRF based on CCTA * No later than one hour before ICA starts, perform a physical examination consisting in instantaneous peripheral blood pressure (systolic and diastolic) resting measurement performed with a standard sphygmomanometer and Continuous Non-Invasive Blood Pressure measurement (1-3 min). Stage 2 After the procedures mentioned above are performed, the patient will undergo elective ICA with the outcomes, i.e.: * video material showing the location of the wire during the FFR measurement, * digital pressure signals exported from the FFR measuring device used to determine the value of the invasive FFR, * values of FFR measurements obtained during ICA will be entered after being anonymised in a dedicated HEMOFLOW PMS\_2020 reference database. Stage 3 Within 48 hours of ICA completion a doctor or another member of the study team trained by the sponsor: * will enter the following data in the Cardiolens FFR-CT Pro system: 1. Patient's data, i.e. patient's ID, gender, height, body mass, exercise tolerability, information on used medications and smoking cigarettes. Optionally, i.e. if upon admission for ICA a blood test was performed as a part of the standard diagnostic workup - haematocrit levels and total protein concentration 2. Files containing CCTA imaging data in the DICOM format. 3. Values of instantaneous peripheral blood pressure (systolic and diastolic) resting measurement performed with a standard sphygmomanometer as well as the digital signal obtained during the CNBP measurement (1-3 min) * Based on the CCTA description or meta data contained in the imaging data the doctor or another member of the study team will record the following information in the CRF: 1. Radiation dose during CCTA 2. Contrast medium dose during CCTA * Will enter the following information in the CRF: 1. Radiation dose during the diagnostic part of ICA 2. Contrast medium dose during the diagnostic part of ICA 3. Number and type of adverse events 4. Duration of the diagnostic workup. Stage 4 Within 7 days of entering all the stage 3 data the investigator (a cardiologist) trained by the sponsor will measure the value of the virtual FFR with the Cardiolens FFR-CT Pro system at locations corresponding to ICA FFR measurements (based on video recording entered in the database during stage 2) Based on results obtained from the Cardiolens FFR-CT Pro system vs reference data an analysis will be performed on meeting the primary and secondary end points of the trial.