Interpretable machine learning analysis of immune-inflammatory biomarkers for predicting no-reflow in patients with acute myocardial infarction after percutaneous coronary intervention.
Pre-procedural neutrophil-centred inflammatory biomarkers are independent correlates of post-PCI no-reflow and offer incremental predictive value over conventional clinical variables, with an interpretable LightGBM model yielding optimal discrimination (AUC 0.799) for peri-procedural risk stratification.
Key Findings
Results
No-reflow occurred in 91 of 382 AMI patients (23.8%) undergoing PCI.
Prospective cohort design with 382 AMI patients undergoing percutaneous coronary intervention.
No-reflow incidence was 23.8% (91 patients).
The cohort included both STEMI and NSTEMI patients, allowing subgroup analyses by AMI subtype.
Results
Multiple neutrophil-centred indices independently correlated with no-reflow after multivariable adjustment.
Univariable and multivariable logistic regression were used to identify independent correlates.
Neutrophil count, NAR (neutrophil-to-albumin ratio), NHR (neutrophil-to-HDL ratio), SII (systemic immune-inflammation index), and PIV (pan-immune-inflammation value) were among the significant markers.
Confounder-adjusted restricted cubic splines (RCS) were used to assess nonlinear associations between biomarkers and no-reflow.
Seven predictors constituted the final model, all with variance inflation factor (VIF) < 2.5, indicating no significant multicollinearity.
Results
The LightGBM machine-learning model yielded the best discrimination among four models tested, with an AUC of 0.799.
Four machine-learning models were developed and compared.
LightGBM achieved AUC 0.799 (95% CI 0.699–0.899) with modest net clinical benefit.
SHAP (SHapley Additive exPlanations) interpretation identified AMI subtype and neutrophil-related markers as dominant predictors in SHAP outputs.
Results
Neutrophil-centred inflammatory biomarkers provided significant incremental predictive value over conventional clinical variables.
Incremental value was assessed using ΔAUC (DeLong test), continuous net reclassification improvement (NRI), and integrated discrimination improvement (IDI).
Seven of 16 tested markers yielded significant continuous NRI.
Ten of 16 tested markers demonstrated significant IDI gains.
Results
Neutrophil count, NLR, and MHR were associated with no-reflow in STEMI but not NSTEMI patients, though formal interaction tests found no significant AMI-subtype effect modification.
Stratified regression analyses were conducted by AMI subtype (STEMI vs. NSTEMI).
Neutrophil count, NLR (neutrophil-to-lymphocyte ratio), and MHR (monocyte-to-HDL ratio) showed associations with no-reflow specifically in STEMI patients.
These associations were not observed in NSTEMI patients.
Formal interaction tests did not reach statistical significance for AMI-subtype effect modification, indicating the differential patterns should be interpreted cautiously.
Methods
LASSO regression was used for predictor selection, and the final seven-predictor model was built with multicollinearity assessment.
LASSO (Least Absolute Shrinkage and Selection Operator) regression selected core predictors from a larger pool of immune-inflammatory biomarkers.
All seven final predictors had VIF < 2.5, confirming absence of problematic multicollinearity.
The study tested 16 immune-inflammatory biomarkers in total for incremental value analyses.
Conclusions
The authors concluded that external validation and recalibration are mandatory before clinical application of the model.
Internal validation was performed using 1000-iteration bootstrapping.
No external validation cohort was included in the study.
The paper explicitly states that 'external validation and recalibration are mandatory before clinical application.'
What This Means
This research studied whether routine blood tests measuring inflammation — particularly markers related to neutrophils (a type of white blood cell) — can predict a dangerous complication called 'no-reflow' in heart attack patients. No-reflow occurs when a blocked coronary artery is physically opened by a procedure (PCI/stenting), but blood still doesn't flow properly to the heart muscle, which worsens outcomes. In a group of 382 heart attack patients, about 1 in 4 (23.8%) experienced no-reflow. The study found that several neutrophil-based inflammation scores measured before the procedure were independently linked to no-reflow risk, even after accounting for other known risk factors.
The researchers built and compared four artificial intelligence (machine learning) models to predict no-reflow, with the best-performing model (LightGBM) achieving an AUC (accuracy measure) of about 0.80 — meaning it could correctly distinguish patients who would and wouldn't develop no-reflow roughly 80% of the time. They also used a technique called SHAP to make the model's decisions transparent and explainable, showing that the type of heart attack (STEMI vs. NSTEMI) and neutrophil-related markers were the most influential factors. Notably, the inflammatory markers added meaningful predictive information beyond what standard clinical variables alone could provide.
This research suggests that simple, widely available blood inflammation tests — particularly those involving neutrophil counts and ratios — could help doctors better identify which heart attack patients are at highest risk for no-reflow before performing the procedure, potentially allowing for more tailored treatment strategies. However, the model was only tested on patients from a single center, and the authors emphasize that further testing in different patient populations is required before this tool could be used in routine clinical practice.
Liu R, Peng Y, Qin H, Zhou Y, Li X, Wang H, et al.. (2026). Interpretable machine learning analysis of immune-inflammatory biomarkers for predicting no-reflow in patients with acute myocardial infarction after percutaneous coronary intervention.. Annals of medicine. https://doi.org/10.1080/07853890.2026.2747562