N–acetylcysteine in Adult Cardiac Surgery: An Umbrella Review of Randomized Evidence on Poaf and Aki

Background Postoperative atrial fibrillation (POAF) and acute kidney injury (AKI) remain frequent complications after adult cardiac surgery. N–acetylcysteine (NAC) has antioxidant and anti–inflammatory properties, but clinical results have been heterogeneous. Methods We conducted an umbrella review of meta–analyses of randomized controlled trials (RCTs) evaluating perioperative NAC in adult cardiac surgery. Outcomes were POAF and AKI (primary) and short–term mortality (secondary). We summarized the most comprehensive evidence across overlapping meta–analyses and quantified overlap using corrected covered area (CCA). Results Ten meta–analyses of RCTs were included. Across the evidence base, NAC was consistently associated with lower POAF risk (pooled estimates typically around RR ∼0.6) (Figure 1), with the signal appearing stronger in protocols using prolonged intravenous administration (48–72 h). In contrast, effects on AKI were neutral overall (pooled estimates around RR ∼0.9), with any potential benefit mainly confined to intravenous–only subgroups in larger (Figure 2) datasets. No clear mortality reduction was observed, and event numbers were limited. Conclusions In adult cardiac surgery, NAC shows the most consistent evidence for reducing POAF, whereas benefits for AKI and mortality remain uncertain. Future trials should standardize POAF surveillance and AKI definitions, prespecify NAC dose/duration, and focus on high–risk phenotypes in whom an intravenous, prolonged regimen may be most biologically plausible.