Lactulose for prevention of cardiovascular events after myocardial infarction: A retrospective cohort study.

Background: Acute myocardial infarction (AMI) remains a major cause of global mortality, with post-infarction cardiovascular events significantly contributing to poor outcomes. Emerging evidence suggests that gut microbiome dysbiosis may influence cardiovascular risk through increased intestinal permeability and systemic inflammation. Although lactulose-a prebiotic known to modulate gut microbiota-has shown beneficial effects in experimental models, its impact on major adverse cardiovascular events (MACEs) after AMI remains unclear. Methods: In this single-center retrospective cohort study, we analyzed 165 AMI patients hospitalized between 2016 and 2019. Participants were stratified by lactulose use during hospitalization. The primary outcome was in-hospital MACEs. Multivariable logistic regression was used. Secondary outcomes included pneumonia incidence and length of hospital stay. Results: After adjustment for confounders, lactulose use was independently associated with a reduced risk of MACEs (adjusted odds ratio (OR) 0.40, 95% confidence interval (CI) 0.16-0.95; p = 0.038). The overall incidence of MACEs was 18.2% in the lactulose group versus 30.0% in controls, though this difference was not statistically significant in unadjusted analysis (χ² = 2.41, p = 0.12), likely reflecting limited statistical power. No significant associations were observed for pneumonia (OR = 0.17, p = 0.09) or hospital stay duration (p = 0.60). Conclusions: In this retrospective analysis, lactulose supplementation was associated with reduced in-hospital cardiovascular events following AMI. However, these preliminary findings require validation in larger prospective studies to establish causality and elucidate underlying gut-mediated mechanisms. If confirmed, lactulose may represent a simple and accessible adjunct therapy in post-infarction care.