Preprocedural neutrophil-to-lymphocyte ratio and recurrence after atrial fibrillation ablation: a systematic review and meta-analysis

Background The neutrophil-to-lymphocyte ratio (NLR) has been investigated as an inflammatory prognostic marker for recurrence after atrial fibrillation (AF) ablation. Differences in exposure scale, recurrence window, effect measure, and covariate adjustment complicate quantitative synthesis. Methods PubMed, Embase, Web of Science, and the Cochrane Library were searched from inception through 28 August 2026 using concepts for AF, catheter ablation, and NLR. All eligible studies were synthesized narratively. A restricted exploratory meta-analysis included only multivariable-adjusted hazard ratios (HRs) for postblanking recurrence that could be expressed per 1-unit increase in preprocedural NLR. Random-effects models used restricted maximum likelihood estimation, with Hartung–Knapp (HK) confidence intervals and prediction intervals. Prognostic-factor evidence was assessed with the Quality In Prognosis Studies (QUIPS) tool, and prediction-model studies were additionally assessed with the Prediction model Risk Of Bias ASsessment Tool (PROBAST). Results Twenty two reports representing 21 studies and approximately 8,633 nonoverlapping participants met the eligibility criteria. Four studies (1,556 participants; 417 recurrence events) contributed to the restricted synthesis. The pooled HR was 1.35 per 1-unit increase in NLR (conventional 95% confidence interval [CI], 0.99–1.85; HK 95% CI, 0.81–2.26), with substantial heterogeneity (I²=92.3%) and a wide 95% prediction interval (0.30–6.01). An extended sensitivity synthesis including one clinically restricted subgroup comprised five studies (1,974 participants; 492 events) and yielded HR 1.34 (conventional 95% CI, 1.05–1.70; HK 95% CI, 0.95–1.88; I²=90.9%; 95% prediction interval, 0.53–3.34). All HK intervals and prediction intervals crossed the null. NLR-alone area under the curve estimates were approximately 0.54–0.72, and incremental predictive performance beyond established variables was not demonstrated. Conclusions Higher preprocedural NLR may be associated with AF recurrence after ablation, but the magnitude and clinical relevance of this association remain uncertain because of substantial heterogeneity, few commensurable studies, and wide uncertainty intervals. NLR should be regarded as a candidate prognostic marker rather than an established risk-stratification tool.