Background: Bile acids play crucial roles in various metabolisms, as well as Lactobacillus in the intestine. But studies on their roles in acute coronary syndrome (ACS) are still insufficient. The aim of this study was to investigate their role and potential association with the severity of coronary lesions and the prognosis of ACS.
Methods: Three hundred and sixty ACS patients were selected. Detection of gut Lactobacillus levels was done through 16S rDNA sequence analysis. Evaluation of the extent of lesions was done using the SYNTAX (SS) score. Mediation analysis was used to assess the relationship between serum total bile acid (TBA), Lactobacillus, atherosclerotic lesions and prognosis of ACS.
Results: Logistic regressive analysis disclosed that serum TBA and Lactobacillus were independent predictors of coronary lesions (high vs. low SS: serum TBA adjusted odds ratio (aOR) = 0.8, 95% confidence interval (CI): 0.6-0.9, p < .01; Lactobacillus: aOR = 0.9, 95% CI: 0.9-1.0, p = .03). According to multivariate Cox regression analysis, they were negatively correlated with the overall risk of all-cause death (serum TBA: adjusted hazard ratio (aHR) = 0.1, 95% CI: 0.0-0.6, p = .02; Lactobacillus: aHR = 0.6, 95% CI: 0.4-0.9, p = .01), especially in acute myocardial infarction (AMI) but not in unstable angina pectoris (UAP). Ulteriorly, mediation analysis showed that serum TBA played an important role as a mediation effect in the following aspects: Lactobacillus (17.0%, p < .05) → SS association (per 1 standard deviation (SD) increase), Lactobacillus (43.0%, p < .05) → all-cause death (per 1 SD increase) and Lactobacillus (45.4%, p < .05) → cardiac death (per 1 SD increase).
Conclusions: The lower serum TBA and Lactobacillus level in ACS patients, especially in AMI, was independently linked to the risk of coronary lesions, all-cause death and cardiac death. In addition, according to our mediation model, serum TBA served as a partial intermediate in predicting coronary lesions and the risk of death by Lactobacillus, which is paramount to further exploring the mechanism of Lactobacillus and bile acids in ACS.KEY MESSAGESLower level of serum total bile acid (TBA) was highly associated with the severity of coronary lesions, myocardial damage, inflammation and gut Lactobacillus in acute coronary syndrome (ACS) patients, especially in acute myocardial infarction (AMI).Lower level of serum TBA was highly associated with mortality (including all-cause death and cardiac death) in patients with ACS, especially with AMI.Serum TBA had a partial mediating effect rather than regulating effect between gut Lactobacillus and coronary lesions and prognosis of ACS.
Keywords: Acute coronary syndrome; Lactobacillus; coronary lesion; prognosis; serum total bile acids.