Association of Angiography-Derived Coronary Microvascular Parameters with Periprocedural Myocardial Injury in Uncomplicated Elective Percutaneous Coronary Interventions

Background: Coronary microcirculation is essential for myocardial perfusion and influences clinical outcomes. The angiography-derived index of microvascular resistance (AMR) is a promising non-invasive tool for assessing microvascular function, but its link to periprocedural myocardial injury (pMI) is unclear. Objectives: To examine coronary flow and microvascular resistance changes during elective PCI and to assess the association between post-PCI microvascular dysfunction (measured by AMR) and pMI occurrence. Methods: Patients with stable coronary artery disease (CAD) undergoing elective PCI from June 2021 to December 2023 were included. Coronary physiology was assessed using AMR, quantitative flow ratio (μFR), and coronary flow velocity ratio (CFVR). High-sensitivity troponin (hsT) levels were measured post-PCI, with pMI defined by the Fourth Universal Definition. Results: Among 330 patients, pMI occurred in 184 (55.8%). Post-PCI, μFR increased from 0.64 ± 0.21 to 0.94 ± 0.06 (p < 0.01), and AMR rose significantly (from 174.92 ± 71.88 to 256.22 ± 55.61 mmHg*s/m, p < 0.01). Microvascular resistance increased in 86.96% of patients. In pMI patients, coronary flow declined (Delta CFVR: −1.53 ± 5.38 vs. 0.26 ± 4.95, p = 0.03), and AMR was significantly higher (265.4 ± 56.4 mmHg*s/m vs. 244.7 ± 52.4 mmHg*s/m, p < 0.01). Microvascular dysfunction was more common in pMI patients (56.5% vs. 39.7%, p < 0.01), especially those with reduced flow velocity (50.0% vs. 19.1%, p < 0.01). Conclusions: This study shows that increased microvascular resistance after PCI—indicated by elevated AMR and reduced RVR—is associated with a higher risk of pMI, while baseline values are not. Despite successful epicardial revascularization, these indices may help guide PCI and evaluate outcomes.