The prognostic value of the index of angiography-derived microcirculatory resistance in patients with STEMI

Background Coronary microvascular dysfunction (CMD) is common in ST-segment elevation myocardial infarction (STEMI) patients despite timely primary percutaneous coronary intervention (PPCI). Angiography-derived microcirculatory resistance (AMR), a novel noninvasive CMD index, offers potential for risk stratification, but its prognostic value in STEMI over mid- and long-term follow-up remains unclear. Methods This retrospective study enrolled 278 STEMI patients between May 2023 and May 2024, excluding those with prior coronary artery bypass grafting, severe left main disease, or poor angiographic quality. The primary endpoint was major adverse cardiovascular events (MACE), including cardiac death, nonfatal myocardial infarction, and stroke. Results During a mean follow-up of 14.30 ± 6.45 months, 44 patients (15.8%) experienced MACE. AMR ≥300 was strongly associated with higher MACE rates and demonstrated superior predictive value compared with corrected TIMI frame count (area under the receiver operating characteristic curve, 0.705, P < 0.001). Restricted cubic spline analysis revealed a nonlinear relationship between AMR and MACE, with a significant increase in risk at AMR ≥300 (nonlinear P = 0.0142). Multivariable Cox regression identified AMR ≥300, age, white blood cell count, and left ventricular ejection fraction (LVEF) as independent predictors of MACE. Incorporating AMR into traditional risk models significantly improved the predictive performance of the MACE (C-index: 0.659 vs. 0.824, P < 0.001). Conclusions AMR ≥300 is an independent predictor of MACE in STEMI patients post-PPCI. Incorporating AMR into risk models improves predictive accuracy, supporting its use in clinical practice.