Comparison of immature platelets fraction (IPF) and neutrophil to lymphocyte ratio (NLR) in left versus right atrium in patients with atrial fibrillation

Background: Atrial fibrillation (AF) confers 3-6-fold increase in the risk of stroke. Anatomical considerations cannot completely explain the higher frequency of left system emboli compared with the right system. Several studies found regional differences in platelet activation and hypercoagulability in the left atrium (LA) compared with systemic circulation in patients with AF, suggesting local contributing factors. Furthermore, there is no clear association between timing of AF and stroke. Thus, stroke in patients with AF probably involves mechanisms additive to cardiac embolism. We aimed to compare factors associated with inflammation, thrombosis and platelet reactivity between left and right atria and systemic circulation in patients with AF.

Methods: Blood samples were prospectively collected from patients undergoing AF or atypical flutter ablations, excluding patients with hematologic problem, an acute inflammatory state or acute coronary syndrome. The blood samples were collected from the femoral vein (FV), right atrium (RA) and LA, just after transseptal puncture and prior to heparin bolus administration, for measurement of Neutrophil to Lymphocyte Ratio (NLR), Immature Platelet Fraction (IPF), C-reactive protein (CRP), CD40 ligand, P-selectin, and E-Selectin. IPF was measured by an autoanalyzer (Sysmex 2100XE, Sysmex America Inc. Mundelein, Illinois), which measures platelet count by optical fluorescence. CD40 ligand, P-selectin and E-Selectin were measured by ELIZA, and NLR was calculated from complete blood counts.

Results: Fifty-two patients were included in the study (age 65±10y, 65% male, CHA₂DS₂-VASc score 2.7±1.8, LA volume index 38.4±13.7 mL/m²). There was no difference between FV, RA and LA regarding NLR (2.84±2.2, 2.95±2.3, 2.89±2.37, respectively), CRP (4.12±4.16 mg/dL, 3.92±3.97, 3.87±3.97, respectively), %IPF (3.9±2, 3.89±2, 3.76±2, respectively), CD40 ligand (611±437, 643±438, 639±447, respectively), P-Selectin (65±28 ng/ml, 64±23, 59±20, respectively), and E-selectin (48±57, 41±15, 39.5±15.6, respectively) (p=NS for all).

Conclusions:

No difference was found between both atria and compared to peripheral blood regarding NLR, %IPF, CRP, CD40 ligand, P-selectin and E-selectin in AF patients. Thus, there does not appear a gradient in thrombogenecity and inflammatory properties between the two atria.