Platelet-to-Lymphocyte Ratio Improves the Predictive Ability of the Risk Score for Atrial Fibrillation Recurrence After Radiofrequency Ablation

Purpose: To investigate the effect and comprehensive predictive value of the platelet-to-lymphocyte ratio (PLR) for long-term recurrence in patients with atrial fibrillation (AF) post ablation. Patients and Methods: We retrospectively analysed 638 consecutive AF patients who underwent ablation, including 302 (47.3%) with paroxysmal AF and 336 (52.7%) with nonparoxysmal AF. Patients were grouped into the recurrence and nonrecurrence groups. Results: After a mean follow-up of 15.1± 9.3 months, 175 patients (27.4%) with AF had long-term recurrence, including 114 patients (33.9%) with nonparoxysmal AF and 61 patients (20.2%) with paroxysmal AF. In the entire cohort and in patients with nonparoxysmal AF, but not in those with paroxysmal AF, the PLR was significantly higher in the recurrence group than in the nonrecurrence group (P< 0.05). After adjusting for the APPLE score, the PLR as a continuous variable independently predicted AF recurrence (hazard ratio HR, 1.003; 95% confidence interval CI, 1.001– 1.005; P< 0.01). The addition of the PLR to the APPLE score improved its predictive ability for recurrence (the C-statistic value increased from 0.645 to 0.675, P=0.02; the net reclassification improvement was 0.221, 95% CI 0.049– 0.394, P=0.01; and the integrated discrimination improvement was 0.029, 95% CI 0.013– 0.045, P< 0.01). For nonparoxysmal AF, the PLR was stratified into tertiles, the PLR independently increased the nonparoxysmal AF recurrence risk after adjusting for multiple confounding factors (HR, 1.393; 95% CI, 1.102– 1.762; P< 0.01), and the addition of the PLR to the left atrial diameter improved its predictive ability for arrhythmia recurrence (the C-statistic value increased from 0.601 to 0.667, P< 0.01). Conclusion: The PLR is an independent predictive factor of long-term AF recurrence post ablation after adjusting for the APPLE score and can improve the predictive ability and clinical usefulness of the APPLE score. However, the PLR is an effective predictor of recurrence in patients with nonparoxysmal AF rather than in paroxysmal AF. Plain Language Summary: AF is a common cardiac arrhythmia that can be treated by catheter ablation. Even though the application of ablation has increased in clinical practice, the AF recurrence rate remains stubbornly high. Predicting the risk of recurrence would allow the optimization of AF treatment and management strategies. The impact of inflammation on atrial fibrillation recurrence is unperceived in the existing AF risk scores. Therefore, we investigated the predictive ability of the platelet-to-lymphocyte ratio, a marker of systemic inflammation that can be easily calculated following routine blood analysis, in estimating the risk of AF recurrence. We found that in the entire cohort and in patients with nonparoxysmal AF, but not in those with paroxysmal AF, the PLR ratio was significantly higher in the recurrence group than in the nonrecurrence group. Adding the platelet-to-lymphocyte ratio to the APPLE risk score improved its ability to predict AF in the entire cohort. In patients with nonparoxysmal AF, the addition of the RLR to the left atrial diameter improved its predictive accuracy. However, the PLR ratio did not predict recurrence of paroxysmal AF. Interestingly, we found that recurrence risk scores, such as the APPLE score and CHA2DS2-VASc, had no predictive value for nonparoxysmal AF. Therefore, the addition of the PLR to the APPLE score should be considered in evaluating AF recurrence risk for patients with an unknown type, and the addition of the PLR to the left atrial diameter should be performed to predict AF recurrence in patients with nonparoxysmal AF. Keywords: platelet-to-iymphocyte ratio, atrial fibrillation, recurrence, prediction model, inflammation, ablation