Distinct gut microbiota signatures and predicted lipid metabolism pathways in Taiwanese patients with acute versus chronic coronary syndromes

BACKGROUND: The gut microbiota plays a pivotal role in host lipid metabolism and cardiovascular health. However, comparative profiling of microbial composition and predicted metabolic functions between acute coronary syndrome (ACS) and chronic coronary artery disease (CAD) remains limited, especially in Asian populations. METHODS: This study employed a cross-sectional microbiome analysis of prospectively enrolled patients, including 20 ACS and 22 CAD patients whose paired stool and serum samples were collected. Fecal bacterial DNA was analyzed using 16S rRNA gene sequencing. Microbial diversity and taxonomic composition were assessed using QIIME2-based pipelines. Functional predictions were performed via PICRUSt2, Tax4Fun, and BugBase, with KEGG and Clusters of Orthologous Groups (COG) annotations. Correlations with serum lipid parameters were also evaluated. RESULTS: Distinct microbial signatures were observed between the ACS and CAD groups. In ACS, Bacteroides plebeius, Tyzzerella, and Sutterella were enriched, whereas Parasutterella and Actinobacteriota were more abundant in CAD. Several taxa were correlated with serum triglyceride, LDL, and HDL levels. Although most lipid metabolism-related pathways were comparable between the groups, nominal differences were noted in linoleic acid metabolism and the biosynthesis of unsaturated fatty acids (p < 0.05; all q > 0.05). BugBase analysis revealed a significantly greater abundance of potentially pathogenic bacteria in ACS patients (q = 0.027). The NSTI scores (mean ± SD = 0.073 ± 0.03) supported the reliability of the functional predictions. CONCLUSIONS: Patients with ACS and CAD demonstrated distinct gut microbiota profiles, with ACS showing enrichment of pro-inflammatory and potentially pathogenic taxa. Although the predicted lipid metabolic functions are largely similar, subtle pathway differences and phenotypic traits suggest that a potential microbiota-lipid axis is associated with cardiovascular disease severity. These findings warrant further investigation in larger cohorts.