The assessment of coronary haemodynamics in patients with саrdiac X syndrome using positron emission tomography

Purpose: the characteristics of coronary hemodynamics were studied by positron emission tomography (PET) in patients with cardiac syndrome X (CSX). Materials and Methods: Sixteen patients with the typical triad of CSX: pain in the chest, ST segment depression during stress ECG test, and angiographically normal coronary arteries were included. Patients with coronary heart disease (CHD) (n=12) and volunteers without cardiovascular disease (n=12) served as the control groups. Cardiac PET with radiopharmaceuticals "Rubidium chloride, 82Rb from the generator" (82Rb-chloride) was performed at rest, during cold pressor test (CPT), and dipyridamole hyperaemia (DH). Absolute values of myocardial blood flow (MBF) were calculated using the software package "Carimas 2.2". Endothelium-dependent and "independent perfusion reserve (EDPR and EIPR, respectively) was calculated based on the values of MBF at rest as well as during CPT and DH. Results: We didn't find significant differences between values of EIPR in patients with CSX and volunteers. Patients with CHD showed a significant decrease in EIPR compared with control groups. In patients with CSX, PET during CPT revealed an insignificant increase in MBF compared to baseline values (6 pts.) or decrease in MBF (10 pts.) suggesting an absence of EDPR or microvascular spasm. MBF during CPT was significantly increased (by over 25% of baseline values) in volunteers. Conclusion: disturbance of endothelium-dependent vasodilatation plays a role in the pathogenesis of myocardial ischemia in patients with coronary syndrome X.