Restricted Coronary Flow Reserve of Mental Stress Induced Myocardial Ischemia in Angina and No Obstructive Coronary Artery Disease

Background: The myocardial blood flow (MBF) mechanism in mental stress-induced myocardial ischemia (MSIMI) in angina with no obstructive coronary artery disease (ANOCA) population is unknown. Methods: 13-NH 3 cardiac PET-CT was utilized to assess MBF and perfusion changes under mental stress (ms) and adenosine stress (as) in ANOCA subjects and gender- and age-matched healthy controls. MSIMI was defined as an increase in perfusion defect score of ≥3 points. Results: Among the 126 participants enrolled, ANOCA women showed a significantly higher prevalence of MSIMI compared to the healthy controls (36/84 vs. 1/42, p <0.001). Perfusion defects under ms occurred synchronously however more pronounced in the left anterior descending and right coronary artery territories, consistent with a significantly higher MBF hyperemia in the left circumflex territory. MBF ms shows a close correlation with rate-pressure product (RPP ms ) ( p <0.05 in ANOCA&MSIMI+, ANOCA&MSIMI-, and control groups with r pearson ranging from 0.39-0.65). Although no differences existed in absolute MBF ms values between groups, there were notable increasing trends among the three groups in corrected MBF, which reflected blood flow supply-demand balance (ANOCA&MSIMI+: 0.96±0.23 vs. control group: 1.10±0.29, p =0.020), and in coronary flow reserve (CFR) (ANOCA&MSIMI+: 2.41±0.75 vs. control group: 2.89±0.77, p =0.016). Furthermore, after adjusting for confounding factors, only subjects in ANOCA&MSIMI+ group did not exhibit a corresponding increase in MBF ms matching MBF as . Conclusion: Restricted CFR, indicating impaired coronary microvascular function, and mismatch between myocardial blood supply and demand together constitute the pathogenic mechanism of MSIMI in ANOCA population. More researches are still needed in exploring the brain-heart interaction in MSIMI.