Quantitative Serum Determination of Angiotensin II and Transforming Growth Factor-β as Biochemical Indicators of Acute Coronary Syndrome Severity: Diagnostic Cutoffs and Correlation with Cardiac Injury Markers

Abstract

Angiotensin II (Ang II), the bioactive octapeptide of the renin-angiotensin system (RAS), and transforming growth factor-β (TGF-β), a 25-kDa homodimeric cytokine, are biochemically coupled molecules central to vascular tone regulation and fibroblast signalling. Both have been implicated in the pathobiology of acute coronary syndrome (ACS), yet their quantitative behaviour across the STEMI/NSTEMI spectrum is incompletely defined. The present case-control study determined serum Ang II and TGF-β by sandwich ELISA in 120 strictly screened subjects (60 controls, 30 STEMI, 30 NSTEMI), and examined the relationship of these analytes with conventional biochemical markers of cardiac injury, lipid metabolism, and glycaemia. Both analytes displayed a graded elevation across the three groups (control < NSTEMI < STEMI; all p < 0.001 by Kruskal-Wallis test). TGF-β achieved the highest single-analyte diagnostic accuracy for ACS versus control (AUC 0.994; 95% CI: 0.981–1.000) at a cutoff of 193.86 pg/mL. Ang II reached AUC 0.946 at 24.82 pg/mL. The Spearman correlation between Ang II and TGF-β was 0.805 (p < 0.001), the tightest pairing in the dataset, consistent with the established upstream role of Ang II in inducing TGF-β expression. Strong correlations with CK-MB (ρ = 0.789 and 0.828) and HbA1c (ρ = 0.694 and 0.732) further support the analytical validity of these markers as biochemical indicators of acute myocardial injury severity.