The proportion of postoperative AKI stages in the unmatched and matched cohort. There was a significant difference in the distribution of AKI stages between HAR and TAR with FET (unmatched: P = 0.012; matched: P = 0.039). More patients developed stage 0 (blue) and stage 1 (red) AKI, lower grade AKI, in the HAR group, regardless of the unmatched or matched cohort. AKI: acute kidney injury; HAR: hybrid type II arch repair; TAR with FET: total arch replacement with frozen elephant trunk.