Angiography-derived microcirculatory resistance as a prognostic marker for patients with ST-segment elevation myocardial infarction post-PPCI

Background Despite timely primary percutaneous coronary intervention (PPCI), coronary microvascular dysfunction (CMD) remains common in ST-segment elevation myocardial infarction (STEMI) patients. Angiography-derived microcirculatory resistance (AMR), a novel CMD index that avoids guidewire use or adenosine administration, has been rapidly developed. Still its prognostic value in STEMI over mid- and long-term follow-up remains unknown. Purpose Our study aimed to evaluate the prognostic value of AMR in STEMI patients and identify risk factors for CMD after PPCI. Methods STEMI patients presenting to our center between May 2023 and May 2024 were prospectively enrolled. Exclusion criteria included prior coronary artery bypass grafting, severe left main stem disease, complex coronary anatomy, poor angiographic quality, or severe chronic obstructive pulmonary disease. QFR and AMR were measured by blinded analysts. The primary endpoint was major adverse cardiovascular events (MACE), including cardiac death, non-fatal myocardial infarction, and ischemic or hemorrhagic stroke. Results A total of 276 patients were included in the final analysis, with 44 patients (15.9%) experiencing MACE during a mean follow-up period of 13.96 ± 6.62 months. AMR demonstrated superior predictive value for MACE compared to QFR (AUC, 0.706 [0.620–0.791], P < 0.001), with an optimal cut-off of 300 based on the Youden index (Figure 1). Kaplan-Meier survival analysis revealed significantly higher incidences of MACE, cardiac death, no Fatal Myocardial Infarction, and heart failure readmission in patients with AMR ≥ 300 versus AMR < 300 (log-rank P< 0.01) (Figure 1). Restricted cubic spline analysis showed a nonlinear relationship between AMR and MACE (nonlinear P= 0.0132), with a marked increase in MACE at AMR ≥ 300 (Figure 1).Multivariable Cox regression analysis identified AMR ≥ 300 (HR, 6.211 [3.013–12.802], P < 0.001), age(HR, 1.037 [1.004-1.070], P=0.026), leukocyte count (HR, 1.031 [1.011-1.051], P=0.002), and left ventricular ejection fraction (HR, 0.970 [0.943-0.999], P=0.040) as independent predictors of MACE, with no significant interactions observed between AMR and clinical subgroups (Figure 2). Adding AMR to the traditional risk model improved predictive performance (C-index: 0.700 vs. 0.660, P < 0.001). Conclusions AMR ≥ 300 is a significant independent predictor of major adverse cardiovascular events (MACE) in STEMI patients following PPCI, with a higher incidence of cardiac death, myocardial infarction, and heart failure readmissions. Incorporating AMR into traditional risk models improves predictive accuracy, highlighting its potential as a valuable tool for risk stratification in STEMI patients.