Comparison of immature platelet fraction and factors associated with inflammation, thrombosis and platelet reactivity between left and right Atria in patients with Atrial fibrillation

Background: Recent trials found poor temporal relationship between atrial fibrillation (AF) episodes and strokes. Thus, stroke in AF patients probably involves more mechanisms than cardiac embolism. We compared factors of inflammation, thrombosis and platelet reactivity between left (LA) and right atria (RA) and femoral vein (FV) in patients with AF. Methods:Blood samples were collected from patients undergoing AF-ablation from the FV, RA and LA for neutrophil to lymphocyte ratio (NLR), immature platelet fraction (IPF) and count (IPC), CD40 ligand, P-selectin and E-Selectin. IPF was measured by an autoanalyzer; CD40 ligand, P-selectin, and E-Selectin were measured by ELISA and NLR was calculated from complete blood counts. Results: Sixty-seven patients were included (age 65±10y, 63% male, CHA2DS2-VASc score 2.8±1.8, LA volume index 40±24 mL/m², 63% paroxysmal AF). There was no difference between FV, RA and LA regarding NLR and CD40 ligand. Factors associated with platelets activity: P-selectin, IPC and IPF% were higher in RA vs LA (60.3 IQR 49.0-76.4 ng/ml vs. 59.3 IQR 49.0-74.7, respectively, p=0.03 for P-selectin, 7.5 IQR 5.2-10 10³/μL vs. 7.1 IQR 5-9.8, p<0.01 for IPC, and 3.6 IQR 2.7-5.0 % vs. 3.6 IQR 2.6-4.8, p<0.01 for IPF%). Similar trends were for E-selectin (41.2 IQR 31.1-51.2 ng/mL vs. 38.7 IQR 27.9-50.4 p=0.09). Similar significant differences were found in patients with CHA₂DS₂-VASC≥2 but not in patients with low score. Conclusions:Patients with AF, especially those with CHA2DS2-VASc≥2, have higher markers of thrombogenicity in RA compared to LA. There was no difference in inflammatory properties between the atria.