Baseline Anemia and Clinical Outcomes Following Transcatheter Edge-to-Edge Mitral Valve Repair: A Systematic Review and Meta-Analysis

Anemia is common among patients undergoing transcatheter edge-to-edge mitral valve repair (TEER) and may be associated with adverse clinical outcomes. However, no previous systematic review or meta-analysis has specifically evaluated clinical outcomes according to baseline anemia status in this population. We conducted a systematic review and meta-analysis to evaluate the association between baseline anemia and clinical outcomes after mitral TEER. A systematic search of PubMed, Embase, the Cochrane Library, ClinicalTrials.gov, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Virtual Health Library (VHL), and Google Scholar was performed to identify studies comparing outcomes in patients with and without baseline anemia who underwent mitral TEER. Random-effects meta-analyses were performed for outcomes with sufficiently homogeneous data, while outcomes unsuitable for quantitative pooling were narratively synthesized. Study quality was assessed using the Newcastle-Ottawa Scale (NOS). Six observational studies involving 34,812 patients were included. Baseline anemia was associated with significantly increased long-term mortality following TEER in the primary pooled analysis (hazard ratio (HR) 1.86, 95% CI 1.57-2.22), with consistent findings in the sensitivity analysis (HR 1.89, 95% CI 1.63-2.21). Baseline anemia was also associated with higher in-hospital mortality (OR 1.42, 95% CI 1.13-1.77). In contrast, pooled analyses of acute kidney injury, long-term composite outcome, and pericardial complications did not demonstrate statistical significance. Baseline preprocedural anemia is associated with increased mortality following transcatheter edge-to-edge mitral valve repair and may identify patients at higher procedural risk. Further prospective studies are needed to determine whether preprocedural optimization of anemia improves clinical outcomes.