What does this research mean for the field?

The Systemic Inflammatory Response Index (SIRI) independently predicts myocardial infarction and major adverse cardiovascular events in patients with unstable angina. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This study investigates the predictive role of the Systemic Inflammatory Response Index (SIRI) for myocardial infarction in patients with unstable angina.

March 5, 2026Open Access

The role of systemic inflammatory response index in predicting myocardial infarction in patients with unstable angina

Key Points

This study investigates the predictive role of the Systemic Inflammatory Response Index (SIRI) for myocardial infarction in patients with unstable angina.
Conducted a retrospective observational study with 129 patients diagnosed with unstable angina.
Calculated SIRI using neutrophil, monocyte, and lymphocyte counts at admission.
Stratified patients into low and high SIRI groups based on ROC analysis cutoff.
Collected clinical, laboratory, and angiographic data to assess outcomes including myocardial infarction and major adverse cardiovascular events (MACE).
Used ROC curves, logistic regression, and Kaplan–Meier analysis for statistical evaluation.
High SIRI levels correlated with a higher incidence of myocardial infarction (38% vs. 10%, p < 0.001).
Patients with high SIRI also showed significantly higher rates of MACE (17.1% vs. 6.1%, p < 0.01).
SIRI demonstrated excellent predictive performance for myocardial infarction with an AUC of 0.858, sensitivity of 90%, and specificity of 94%.
Multivariate logistic regression confirmed SIRI as an independent predictor of myocardial infarction (OR = 2.15, 95% CI: 1.25–3.71).

Abstract

Background Unstable angina (UA) is a high-risk presentation of acute coronary syndrome (ACS) that can rapidly progress to myocardial infarction (MI) if not identified and managed promptly. Inflammation plays a key role in plaque instability and thrombotic events, making inflammatory biomarkers useful tools for early risk assessment. The Systemic Inflammatory Response Index (SIRI), derived from peripheral blood cell counts, has emerged as a novel marker of systemic inflammation, but its prognostic utility in UA remains underexplored. Objective The purpose of this study was to investigate the role of the Systemic Inflammatory Response Index (SIRI) in predicting myocardial infarction and major adverse cardiovascular events (MACE) in patients presenting with unstable angina. Methods This retrospective observational study included 129 adult patients diagnosed with unstable angina and admitted to a tertiary care center. SIRI was calculated as (neutrophil count × monocyte count)/lymphocyte count using laboratory values obtained at admission. Patients were stratified into low and high SIRI groups based on a cutoff derived from ROC analysis. Clinical, laboratory, and angiographic data were collected, and outcomes including MI and MACE (composite of MI, cardiovascular death, stroke, and urgent revascularization) were assessed. ROC curves, logistic regression, and Kaplan–Meier analysis were used for statistical evaluation. Results Patients with high SIRI levels had significantly higher rates of myocardial infarction (38% vs. 10%, p 0.001) and MACE (17.1% vs. 6.1%, p 0.01). SIRI demonstrated excellent predictive performance for MI with an AUC of 0.858, sensitivity of 90%, and specificity of 94%. Multivariate logistic regression confirmed SIRI as an independent predictor of MI (OR = 2.15, 95% CI: 1.25–3.71). Conclusion SIRI is a simple, accessible, and powerful inflammatory marker that independently predicts myocardial infarction and MACE in patients with unstable angina. Its integration into early risk assessment may enhance clinical decision-making and improve patient outcomes.

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