Angio-IMR promising diagnosis approach for identifying ischemia in ANOCA patients, suggests study

A new study published in the International Journal of Cardiology found proof regarding the ability of the angiography-derived index of microcirculatory resistance (angio-IMR) to accurately diagnose ischemia in angina with non-obstructive coronary artery disease (ANOCA).

30%-70% of patients undergoing coronary angiography (CAG) had angina with non-obstructive coronary artery disease (ANOCA). Additionally, a large portion of ANOCA is caused by coronary microvascular dysfunction (CMD). ANOCA has been effectively assessed using functional evaluations based on pressure wires. However, the intrusive aspect, the administration of hyperemic medicines, and the increased expense have limited its practical utility.

Angina with non-obstructive coronary artery disease is largely caused by coronary microvascular dysfunction (CMD). Although it was created for the assessment of CMD, the angiography-derived index of microcirculatory resistance (angio-IMR) has not yet received enough validation in ANOCA. Thus, Jingpu Wang and colleagues carried out this investigation to examine the diagnostic efficacy of angio-IMR for ischemia in ANOCA patients and to validate it against wire-based IMR.

2 separate cohorts were included in this investigation. In the wire-based IMR validation cohort, 74 patients (74 vessels) had their angio-IMR and wire-based IMR assessed. 136 patients (408 vessels) in the SPECT-MPI validation cohort successfully underwent angio-IMR and single-photon emission computed tomography-myocardial perfusion imaging (SPECT-MPI). The myocardial perfusion defect on SPECT-MPI and a summed difference score (SDS)≯≥ 2 were used to indicate ischemia.

The angio-IMR ≥ 25 expressed a high diagnostic efficiency and classification agreement (CA) of 91.9% with the reference wire-based IMR ≥ 25 in the wire-based IMR validation cohort. The high angio-IMR group (angio-IMR ≥25) showed greater ischemia in the SPECT-MPI validation cohort than the low angio-IMR group (angio-IMR <25).

With a modest diagnostic performance for ischemia, the angio-IMR ≥ 25 may help distinguish between ischemia and other conditions in patients with ANOAC (integrated discrimination improvement (IDI): 0.184; and net reclassification improvement (NRI): 0.217).

Overall, Angio-IMR and wire-based IMR showed high diagnostic performance and agreement among the ANOCA population in this investigation. Angio-IMR ≥ 25 showed noteworthy efficacy and advantage in detecting ischemia, suggesting that angio-IMR might offer useful data and support ANOCA patient risk classification. 

Source:

Wang, J., Li, C., Zhang, M., Zhou, J., Zhang, Q., Guo, W., Pan, C., Yu, H., Chang, S., Lu, H., Chen, Z., Shi, H., Zhang, F., Qian, J., & Ge, J. (2025). The performance of angiography-derived index of microcirculatory resistance for ischemia in angina with non-obstructive coronary artery disease: Validated by wire-based IMR and SPECT-MPI. International Journal of Cardiology, 133236. https://doi.org/10.1016/j.ijcard.2025.133236