Prognostic Value of Coronary Angiography-Derived Index of Microcirculatory Resistance in Patients With Intermediate Coronary Stenosis.

Summary

In 1,658 FLAVOUR patients with intermediate stenosis, angio-IMR >25 was associated with markedly higher 2-year POCO rates in both PCI (35.1% vs 7.2%) and non-PCI (18.0% vs 4.2%) groups, and remained independently predictive after adjustment. Adding angio-IMR significantly improved discrimination and reclassification over angiographic and clinical models.

Key Findings

• Angio-IMR >25 was associated with higher 2-year POCO in PCI patients (35.06% vs 7.2%; P<0.001) and non-PCI patients (17.95% vs 4.23%; P<0.001).
• Angio-IMR >25 independently predicted POCO after adjustment (PCI HR 6.235; 95% CI 3.811-10.203; non-PCI HR 5.282; 95% CI 2.948-9.462).
• Adding angio-IMR improved prognostic performance (e.g., angiographic model C-index 0.710 vs 0.615; NRI 0.268; IDI 0.055; all P<0.001).

Clinical Implications

Angio-IMR can be integrated into cath-lab workflows to identify high-risk intermediate lesions regardless of PCI, informing intensified medical therapy, closer follow-up, or adjunctive physiologic assessment.

Limitations

• Post hoc nature may introduce residual confounding and limits causal inference.
• Angio-IMR threshold (>25) and generalizability require external validation and standardization.

Future Directions

Prospective validation of angio-IMR thresholds, integration with FFR/iFR and imaging, and trials testing angio-IMR–guided management strategies for intermediate lesions.