The study aims to determine a diagnostic marker for regionally impaired myocardial oxygenation response in patients with suspected coronary artery stenosis.

This observational applied research international study aims to assess the validity of breathing maneuvers as a vasoactive maneuver and Oxygenation-Sensitive Cardiac Magnetic Resonance Imaging (OS-CMR) in a patient population. OS-CMR results will be compared to the clinical gold standard of Fractional Flow Reserve (FFR) and instant wave-free ratio (iFR) as a secondary objective, to determine if this non-invasive, no pharmaceutical agent imaging technique can identify areas of oxygenation deficit in myocardium perfused by a stenosed coronary artery.

Inclusion Criteria:

Healthy Participants

• Age: > 40y
• No known current or pre-existing significant medical problems that would affect the cardiovascular or respiratory system.

CAD Patients

• Age > 18 y
• Indication for invasive coronary angiography based on symptoms and a test positive for inducible coronary ischemia, or previous coronary angiography.

Exclusion Criteria:

ALL participants:

• General MRI contraindications: Pacemakers, defibrillating wires, implanted defibrillators, intracranial aneurysm clips, metallic foreign bodies in the eyes, knowledge or suspicion of pregnancy.
• Consumption of caffeine (coffee, tea, cocoa, chocolate, "energy drink") during the 12 hours prior to the exam.
• Regular nicotine consumption during the last 6 months.

Patients only

• Vasoactive medication (e.g. nitro) during the 12 hours prior to the exam Contraindications to adenosine (2nd or 3rd A-V block, sinus node disease, asthma, bronchoconstrictive diseases).
• Acute Coronary Syndrome (ACS), or previous Coronary Artery Bypass Surgery
• Previous myocardial infarction within 1 month
• Clinically unstable condition
• Significant or uncontrolled arrhythmia

Study population will be composed of patients with suspected or known CAD and healthy volunteers. The primary group will consist of patients with 1- or 2-vessel CAD. Patients diagnosed with 3-vessel or no obstructive disease in an angiography visit after the CMR exam will be included as a sub-group, with not more than 25% of the study population being in this group. Healthy volunteers will serve to act as a control for the assessment of a diagnostic cut-off.

Patient who performed the CMR and then the angiography, who are deemed to have no obstructive (no vessel) CAD or 3-vessel CAD, will be assigned to a subgroup of the study. No vessel disease will be those who have no vessel stenosis of >0.75. 3-vessel disease will be those who have a stenosis of >0.75 in all three coronary arteries.