The C-reactive protein–albumin–lymphocyte index as a predictor of new-onset atrial fibrillation after ST-segment elevation myocardial infarction: A retrospective cohort study

Objective New-onset atrial fibrillation is a common complication following ST-segment elevation myocardial infarction and is associated with poor prognosis. The C-reactive protein–albumin–lymphocyte index, a composite biomarker reflecting inflammation, nutritional status, and immune function, has not been fully evaluated for its predictive value for new-onset atrial fibrillation. Methods This single-center retrospective study included 665 consecutive patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention between January 2023 and October 2025. The C-reactive protein–albumin–lymphocyte index was calculated from admission laboratory values. New-onset atrial fibrillation was defined as the first documented episode of atrial fibrillation within 30 days after percutaneous coronary intervention. Multivariable logistic regression, receiver operating characteristic curve analysis, and reclassification metrics were used to assess its predictive performance. Results New-onset atrial fibrillation occurred in 56 patients (8.4%). In the multivariable model adjusting for age, heart rate, left atrial diameter, infarct-related artery-right coronary artery, left ventricular ejection fraction, fasting blood glucose, and C-reactive protein–albumin–lymphocyte index, five variables remained independently associated with new-onset atrial fibrillation: left atrial diameter (odds ratio = 1.179), infarct-related artery-right coronary artery (odds ratio = 1.992), left ventricular ejection fraction (odds ratio = 0.933), fasting blood glucose (odds ratio = 1.321), and C-reactive protein–albumin–lymphocyte index (odds ratio = 0.813) (all p < 0.05). Among individual biomarkers, the C-reactive protein–albumin–lymphocyte index demonstrated the highest predictive ability (area under the curve = 0.743; 95% confidence interval: 0.685–0.801). Adding the C-reactive protein–albumin–lymphocyte index to a baseline model comprising age, heart rate, left atrial diameter, infarct-related artery-right coronary artery, left ventricular ejection fraction, and fasting blood glucose significantly improved reclassification (net reclassification improvement = 0.7323; p < 0.001; integrated discrimination improvement = 0.0593; p = 0.005). Conclusions In this retrospective single-center cohort, a lower admission C-reactive protein–albumin–lymphocyte index was independently associated with clinically documented 30-day new-onset atrial fibrillation after percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction and may provide incremental predictive information, whereas external validation is required before clinical application.