Mental Stress-Induced Myocardial Ischemia Detected by Global Longitudinal Strain and Quantitative Myocardial Contrast Echocardiography in Women With Nonobstructive Coronary Artery Disease

Background The utility of radionuclide myocardial perfusion imaging including positron emission tomography (PET) for diagnosing mental stress-induced myocardial ischemia (MSIMI) is clinically restricted. This study aims to assess the diagnostic performance of novel echocardiographic techniques, including automated strain and quantitative myocardial contrast echocardiography (MCE) with dedicated software and deep neural network model, for MSIMI detection. The secondary objective was to explore the correlation between changes in myocardial blood flow and MSIMI. Methods Seventy-two female patients ages 18 to 75 with angina and nonobstructive coronary artery disease (ANOCA) and 23 healthy controls were prospectively recruited. Both echocardiography with contrast agent and PET imaging were performed during structured mental stress testing. Mental stress-induced myocardial ischemia was defined as a summed difference score >= 3 on PET. Echocardiographic parameters including left ventricular global longitudinal strain, beta, and A x beta were obtained, and their trends during mental stress testing were observed. Delta GLS was defined as the ratio of difference between global longitudinal strain values at stress and rest to the rest data. beta reserve and Ax beta reserve were respectively calculated. Results Thirty-two ANOCA patients (44%) and 1 control (4%) were diagnosed with MSIMI (P < .01). For ANOCA patients with MSIMI, left ventricular GLS, beta, and A x beta declined to varied extents during mental stress testing compared with those without MSIMI and the controls (P < .05). Bland-Altman plots demonstrated good consistency between beta reserve and A x beta reserve output by the deep neural network model and iMCE software. Receiver operating characteristic curve analyses showed that Delta GLS, beta reserve, and A x beta reserve demonstrated favorable ability to predict MSIMI, especially the combination of A x beta reserve using iMCE analysis and Delta GLS (area under the curve, 0.94; sensitivity, 83%; specificity, 97%). Conclusions Novel technologies in echocardiography exhibit the potential to be a clinical alternative to cardiac PET for effectively detecting MSIMI. Attenuated myocardial blood flow response during structured mental stress testing was correlated with MSIMI, providing a reasonable explanation for the chest discomfort persisting in ANOCA women.