More than 50% of patients with stable or unstable angina pectoris have no obstructive coronary arteries by angiographic visual estimation, in which coronary microvascular dysfunction (CMD) is one of the causes of myocardial ischemia and chest pain. Presently, the index of microcirculatory resistance (IMR) measured by the pressure wire is recognized as standard for evaluating coronary microcirculatory function. A coronary angiography-derived index of microcirculatory resistance (caIMR) is proposed for physiological assessment of microvascular diseases in coronary circulation without pressure wire, hyperemic agents, or thermodilution method.~This study is a prospective, multi-center clinical trial. In the study, IMR (measured by pressure wire) will be used as a reference standard to evaluate the feasibility, accuracy and safety of caIMR measured by a non-invasive diagnosis system (FM21a) based on angiography images and aortic pressure wave. 116 patients eligible for inclusion criteria will be enrolled in the study. Both IMR and caIMR measurement will be performed in the same patient in a random order after angiography. The definitions of IMR and caIMR for coronary microcirculatory ischemia are IMR≥25 and caIMR≥25. The primary endpoint is the diagnostic accuracy of caIMR. The secondary endpoint is caIMR's sensitivity, specificity, positive predictive value, negative predictive value, ROC curve and AUC of caIMR diagnosis, and the diagnostic characteristics of caIMR at the vascular level.
More than 50% of patients with stable or unstable angina pectoris have no obstructive coronary arteries by angiographic visual estimation, in which coronary microvascular dysfunction (CMD) is one of the causes of myocardial ischemia and chest pain. A coronary angiography-derived index of microcirculatory resistance (caIMR) is proposed for physiological assessment of microvascular diseases in coronary circulation. The aim of the trial is to assess diagnostic performance of caIMR, using wire-derived index of microcirculatory resistance (IMR) as the reference standard.