In STEMI patients, angio-IMR exhibited a significantly positive correlation with both MVO extent and infarct size, demonstrating the diagnostic value of this wire-free method for assessing microvascular injury, while a single bolus of recombinant staphylokinase before PCI was associated with numeric but non-significant reductions in post-PCI angio-IMR, MVO, and infarct size.
Post-PCI angio-IMR was positively correlated with MVO extent in STEMI patients.
Post-PCI angio-IMR was positively correlated with infarct size in STEMI patients.
Angio-IMR demonstrated moderate diagnostic performance for detecting MVO on CMR.
Pre-PCI administration of recombinant staphylokinase (r-SAK) was associated with numerically lower post-PCI angio-IMR compared to normal saline, but the difference was not statistically significant.
Pre-PCI r-SAK was associated with numerically lower rates of MVO compared to normal saline, but the difference did not reach statistical significance.
The study evaluated a wire-free angiography-based method (angio-IMR) for assessing microvascular obstruction after PCI in STEMI patients.
This research studied a newer, simpler way to measure blood flow problems in the tiny blood vessels of the heart (called microvascular obstruction or MVO) after a heart attack is treated with a procedure to open the blocked artery (PCI). The method, called angio-IMR, uses only standard X-ray imaging already done during the procedure, without needing extra specialized wires inserted into the heart arteries. The study involved 123 heart attack patients who were also randomly assigned to receive either a clot-dissolving drug (recombinant staphylokinase, r-SAK) or a placebo (salt water) before their procedure. The researchers found that angio-IMR readings taken right after the procedure were meaningfully linked to both the extent of microvascular obstruction and the size of the heart muscle damage, as measured by MRI scans. When angio-IMR values were around 40 units or higher, they could predict significant MVO and large infarct size with moderate accuracy. The clot-dissolving drug r-SAK was associated with lower angio-IMR values and less MVO and heart muscle damage compared to placebo, but these differences were not large enough to be considered statistically definitive, possibly because the study was not large enough to detect these differences reliably. This research suggests that angio-IMR could be a practical, readily available tool for heart attack patients — since it requires no extra equipment beyond what is already used — to identify patients who have significant damage to the small blood vessels of the heart after their artery is reopened. This matters because microvascular obstruction after heart attack treatment is associated with worse outcomes, and having a simple way to detect it could help guide future treatment decisions. The findings also hint that giving a clot-dissolving drug before the procedure might reduce microvascular injury, but larger studies would be needed to confirm this.
Wu T, Zhang X, Li C, Hu Y, Dong M, Chai J, et al.. (2026). Angiography-Based Index of Microcirculatory Resistance in Assessing the MVO and Infarct Size in STEMI Patients.. Clinical cardiology. https://doi.org/10.1002/clc.70464