The Association Between Catheter-based Absolute Coronary Flow and Resistance and 15O-H2O Positron Emission Tomography Scan Based Absolute Myocardial Blood Flow in the Coronary Artery Territory

Aims 1. To assess the correlation between absolute flow and resistance assessed by catheter-based thermodilution technique using CoroFlow®-system and myocardial blood flow (MBF) measured by positron emission tomography (PET) and the tracer \[15O\] labeled water (\[15O\]H2O) (15O-H2O PET) 2. To assess the correlation between impaired MBF measured with 15O-H2O PET and negative fractional flow reserve (FFR) and index of microvascular resistance (IMR) level. Hypothesis: In patients with angina pectoris and reduced MBF measured with 15O-H2O PET but no hemodynamic significant stenosis (FFR \> 0.80), the IMR is \>25 measured with continuous thermodilution indicating microcirculatory dysfunction. Methods: We include patients with angina pectoris and suspected coronary disease based on a cardiac-computerised tomography (CT) scan. Patients are then referred to an 15O-H2O PET (rest and stress) and then a diagnostic invasive coronary angiography (ICA) with physiological assessment.