Diagnostic performance of angiography-derived IMR for coronary microcirculation disease assessment in INOCA patients

Diagnosis of coronary microcirculatory dysfunction with wire-based methodology imposes a risk of unplanned revascularization in patients with ischemia and no obstructive coronary arteries (INOCA). Non-invasive, angiography-based methods are introduced to alleviate this risk. The angiography-based index of microcirculatory resistance (IMRangio) is a computational fluid dynamics (CFD)-based index utilizing high-quality angiography and aortic pressures to calculate a surrogate of the index of microcirculatory resistance (IMR).

This study aims to assess the correlation between IMRangio and invasive thermodilution-based IMR in INOCA patients qualified to the MOSAIC-COR registry.

Data from 74 patients (92 coronaries including 52 left anterior descending arteries) from the MOSAIC-COR registry were used for this sub-analysis. All patients had undergone complex coronary physiology assessment using a thermistor-equipped wire and thermodilution-based methodology with subsequent vasomotor acetylcholine vasospasm testing. Post-hoc, CFD-based angiogram analysis was performed to calculate IMRangio values.

The median age of patients was 64 years, and 59.3% were female. The median calculated value of IMRangio was 29 (Q1-Q3: 22-46), whereas the invasively measured IMR median value was 17 (Q1-Q3: 13-26). A significant correlation between IMRangio and invasive-IMR was observed (Spearman rho 0.29, < 0.001). Angiography based index of microcirculatory resistance area under the curve (AUC) was 62.2, and a value > 46.5 U was identified as the best cut-off for prediction of IMR > 25 and provided 38% sensitivity and 82% specificity to detect coronary microcirculatory dysfunction (CMD).

The angiography-based index of microcirculatory resistance significantly correlates with invasively measured IMR; however, a higher cut-off value should be considered to improve the specificity of the method to detect CMD.