Perfusion Estimation For Optimal Treatment Strategy in Chronic Coronary Syndrome

Inclusion Criteria: 1. Age \> 18 years 2. Willing to participate and able to understand, read and sign the informed consent document before the planned procedure 3. Known ischemic heart disease defined as one of the following 1. Previous myocardial infarction, percutaneous coronary intervention or coronary artery bypass grafting 2. Previous coronary computed tomography angiography or invasive coronary angiography documenting atherosclerosis. 4. Undergoing clinically indicated \[15O\]H2O cardiac PET/CT due to chest discomfort or dyspnea as angina equivalent Additional inclusion criteria for randomized trial: 5. Initial \[15O\]H2O cardiac PET/CT with abnormal perfusion defined as all of the following 1. Hyperemic myocardial blood flow (hMBF) ≤2.3 mL/min/g in at least two adjacent myocardial segments 2. Relative hMBF ≤ 65% in at least two adjacent segments as compared with the mean hMBF of the two adjacent segments with the highest mean hMBF 3. Tissue perfusion defect extent ≥ 5% based on indices of relative hypoperfusion 6. Clinical indication for invasive coronary angiography decided at a multidisciplinary conference between consultants in nuclear medicine and cardiology Exclusion Criteria: 1. Ongoing acute coronary syndrome or acute coronary syndrome within 30 days 2. Contraindications for adenosine 1. Severe asthma 2. Advanced atrioventricular block without pacemaker 3. Severe aortic stenosis 3. Patients not able to breath hold (severe COPD/asthma) 4. Pregnant women, including women who are potentially pregnant or lactating 5. Allergy to iomeron 6. Life expectancy of less than 2 years 7. Severe valvular disease 8. Reduced kidney function with an estimated glomerular filtrations rate \<40 ml/min 9. Inability to consent Additional exclusion criteria for randomized trial: 10. Unprotected left main coronary artery stenosis on coronary CT angiography 11. Very large perfusion defect on initial \[15O\]H2O cardiac PET/CT indicating left main coronary artery stenosis or balanced ischemia defined as tissue perfusion defect extent based on indices of absolute hMBF ≥ 20% in two or more myocardial territories supplied by coronary arteries with an Agatston calcium score ≥ 300