The Prognostic Value of Neutrophil-to-Lymphocyte Ratio on Mortality in Patients Undergoing Transcatheter Aortic Valve Implantation: A Systematic Review and Meta-Analysis.

Transcatheter aortic valve implantation (TAVI) has emerged as a revolutionary treatment for severe aortic stenosis, but predicting post-procedure outcomes remains challenging. This systematic review and meta-analysis investigated the association between neutrophil-to-lymphocyte ratio (NLR) and mortality in TAVI patients. We searched major databases from January 2010 to November 2024, including studies examining pre-procedural NLR and mortality outcomes in TAVI patients. Eight retrospective studies comprising 9,948 participants were included. The follow-up duration ranged from three to 36 months. Meta-analysis using a random-effects model revealed that elevated NLR was significantly associated with increased mortality risk (RR: 1.37, 95% CI: 1.08-1.74). Substantial heterogeneity was observed (I-square: 77.3%). Meta-regression analysis identified follow-up duration as a significant predictor explaining 62.5% of the heterogeneity, while other variables including age, gender, diabetes, and hypertension showed minimal impact. Sensitivity analyses demonstrated the robustness of findings, with no individual study significantly influencing the overall effect size. The association between elevated NLR and increased mortality risk may be explained by neutrophils' role in inflammatory responses and tissue damage, coupled with reduced lymphocyte-mediated immune regulation. Despite limitations including NLR cut-off variations and heterogeneity in study designs, our findings suggest that NLR serves as a valuable prognostic marker for mortality risk in TAVI patients. Future research should focus on standardizing NLR thresholds and exploring subgroup-specific effects to enhance its clinical utility.