In-hospital postoperative outcomes in redo versus primary coronary artery bypass grafting: a propensity score-matched retrospective cohort study

Characterizing in-hospital complications following coronary artery bypass grafting (CABG) and redo CABG is critical to refining postoperative care and improving patient prognosis. This study compared in-hospital complications and outcomes between redo and primary CABG. In this retrospective cohort study, 1,098 records of patients who underwent isolated CABG at a tertiary hospital in Tehran, Iran, from 2021 to 2023 were reviewed. After eligibility screening and exclusion of incomplete records, 925 records remained: 847 primary CABG and 78 redo CABG. Propensity scores were estimated, and 1:1 optimal matching produced 78 matched pairs. Statistical analyses were performed using SPSS version 26. A p value < 0.05 was considered statistically significant. Before matching, most baseline characteristics were similar between the two groups; however, redo CABG patients were significantly older than primary CABG patients (61.60 ± 4.12 vs. 52.93 ± 6.62 years; p < 0.001). In-hospital mortality and hospitalization time were higher in the redo CABG group, whereas most individual postoperative complications were not significantly different between groups. After propensity score matching, baseline characteristics were well balanced. In the matched cohort, in-hospital mortality remained higher after redo CABG (9.0% vs. 1.3%; p = 0.031), and hospitalization time was longer (14.59 ± 2.26 vs. 10.76 ± 1.85 days; p < 0.001). Most postoperative complications did not differ significantly. Redo CABG was associated with higher in-hospital mortality and longer hospitalization, whereas no statistically significant differences were detected for most individual postoperative complications. These findings may support improved risk stratification and postoperative surveillance in redo CABG patients.