Associations of the aggregate index of systemic inflammation (AISI) with myocardial injury markers in patients with coronary heart disease

Background The Aggregate Index of Systemic Inflammation (AISI) is a potential cardiovascular risk indicator. Its association with contemporaneous myocardial injury in coronary heart disease (CHD) patients remains unclear.Objective To explore the association between AISI and elevated myocardial injury markers and evaluate its discriminatory performance.Methods In this single-centre retrospective study of consecutive CHD patients, AISI was calculated at admission. The patients were assessed at admission and before coronary angiography. Elevated cTnT was defined as >0.014 ng/mL and elevated CK-MB as >24 U/L. Logistic regression, subgroup analyses, ROC curves, and restricted cubic splines (RCS) were used.Results Significant differences across AISI tertiles were observed in adverse profiles. In multivariable-adjusted models, each unit increase in continuous AISI was associated with higher odds of elevated cTnT (OR = 1.30, 95% CI: 1.10, 1.55, p = 0.003) and elevated CK-MB (OR = 1.09, 95% CI: 1.02,1.17, p = 0.01). Compared with T1, T3 showed a significantly increased risk of elevated cTnT (OR = 3.14, 95% CI: 1.93,5.12, p < 0.01). Subgroup analyses revealed that AISI was more strongly associated with cTnT elevation in patients aged <70 years and in men, while the association with CK-MB was more evident in women and those aged ≥70 years. ROC analysis demonstrated moderate predictive value for cTnT (AUC = 0.72, 95% CI: 0.69, 0.75) and limited value for CK-MB (AUC = 0.65). RCS identified a nonlinear relationship with cTnT (P for nonlinearity = 0.0016), with an inflection point at 212.41.Conclusion Elevated AISI is independently associated with myocardial injury biomarkers in CHD patients, particularly for cTnT elevation, with a nonlinear threshold effect near 212.4. This association varies by age and sex, suggesting that AISI may serve as a simple, cost-effective adjunctive marker for identifying CHD patients at risk of myocardial injury.