Myocardial blood flow mechanism of mental stress-induced myocardial ischemia in women with ANOCA

Mental stress-induced myocardial ischemia (MSIMI) is linked to a 2-fold increase in cardiovascular events, but its underlying myocardial blood flow (MBF) mechanisms remain underexplored. Using nitrogen-13-ammonia cardiac positron emission tomography-computed tomography (PET-CT) assessing myocardial perfusion defect and MBF under resting, mental stress (MS), adenosine stress (AS) conditions, angina with no obstructive coronary artery disease (ANOCA) women showed a significantly higher prevalence of MSIMI compared to age-matched healthy controls (36/84 vs. 1/42, p < 0.001). The MBF_AS and rate-pressure product-corrected MBF_MS were consistently lower, especially in the left anterior descending artery territory, in participants with increased perfusion defect scores under MS. The lowest values of restricted coronary flow reserve and corrected MBF_MS in participants of ANOCA&MSIMI+ group indicated that impaired coronary microvascular function and mismatch between myocardial blood supply and demand together constitute the pathogenic mechanism of MSIMI in ANOCA population. These findings deepen our understanding of the pathophysiological mechanisms of MSIMI and confirm the long-standing hypothesis of the involvement of impaired coronary microvascular function.