Novel predictor of thrombosis after left atrial appendage closure -Neutrophil to Lymphocyte Ratio (NLR), platelet to LymPhocyte Ratio (PLR), and Lymphocyte to Monocyte Ratio (LMR)-

Abstract Background Cardiogenic embolism by left atrial thrombi is one of the most important atrial fibrillation (AF)-related clinical problems. In a previous survey, 91% of nonrheumatic AF-related left atrial thrombi was originated in the left atrial appendage (LAA). The WATCHMAN device was developed as a permanent implantable device to seal off the LAA to prevent cardiogenic embolism. It has been used in Japan since September 2019. The WATCHMAN family is the only left atrial appendage closure (LAAC) device in Japan. After percutaneous left atrial appendage closure (LAAC), DRT is an important issue in some cases. Neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and lymphocyte to monocyte ratio (LMR) are known as cancer prognostic factors and indicators of immune status. There are few reports on the predictor for device related thrombosis (DRT), transient ischemic attack (TIA), and ischemic stroke. Finding novel biomarkers could help clinical decision in antithrombotic therapy post LAAC and follow-up intervals. Purpose To investigate the association of NLR, PLR, and LMR with device related thrombosis, transient ischemic attack, and ischemic stroke in patients with LAAC. Methods Our database of LAAC was respectively analyzed. All LAAC cases were performed between January 2020 and September 2023. Blood cell counts were sampled in three days before LAAC. Postoperative antithrombotic therapy was individualized based on the patient’s background. We examined their background and clinical events. Results A total of 116 consecutive patients underwent LAAC in our institution excepting for one case that could not be performed due to a huge LAA (follow-up period, 610±37 days; age, 75±1 years; male sex, 73%; left ventricular ejection fraction, 58±1%; CHAD2S2-VASc, 4.6±0.1; HAS-BLED, 3.4±0.1). The results are shown in the Figure. Receiver-operating characteristic curve analysis confirmed the best cut-off value of NLR, PLR, and LMR for composite of DRT, TIA, and ischemic stroke (AUC = 0.69; 0.70; 0.67). In the univariate analysis, NLR<1.88, PLR<144, and LMR>3.40 are the independent predictor for the combination of DRT, TIA, and ischemic stroke (p-value = 0.02; 0.04; 0.05, respectively). Conclusion Low NLR, low PLR, and high LMR are the independent predictor for the combination of DRT, TIA, and ischemic stroke. These parameters can be useful in routine use because they can be easily calculated without additional costs.