Gut microbiota dysbiosis in post-cardiac arrest syndrome: mechanisms, clinical implications, and therapeutic perspectives.

Post-cardiac arrest syndrome (PCAS) is a complex pathophysiological condition triggered by systemic ischemia-reperfusion injury following cardiac arrest and is frequently associated with multi-organ dysfunction and poor neurological outcomes. Emerging evidence suggests that the gut microbiota, increasingly recognized as a key regulator of host immunity, metabolism, and intestinal barrier integrity, may participate in the pathogenesis and progression of PCAS. Alterations in microbial composition and function following cardiac arrest have been associated with systemic inflammation, immune dysregulation, impaired intestinal barrier function, and gut-brain axis-mediated neurological injury. This narrative review summarizes current evidence regarding gut microbiota alterations after cardiac arrest and discusses their potential mechanistic links with PCAS progression. We further review emerging associations between microbial signatures and clinical outcomes and explore microbiota-targeted therapeutic approaches, including probiotics, prebiotics, and other microecological interventions. Given that direct evidence in PCAS remains limited, mechanistic insights derived from related critical illnesses are also discussed where biologically relevant. A better understanding of host-microbiota interactions may facilitate the identification of novel biomarkers and therapeutic targets and support the development of adjunctive strategies to improve outcomes after cardiac arrest.