Background and Objectives Contemporary pacemaker devices are able to quantify atrial high-rate episodes (AHREs) and atrial fibrillation burden (AFB) accurately. In this study, we aim to assess the relationship of thrombogenesis markers in association with AHREs and AFB.

Methods We studied 87 patients with dual-chamber pacemaker. Patients on warfarin were excluded. AHREs were defined as atrial-rate ≥220 beats/min and ≥5 minutes. AFB and percentage of cumulative pacing were derived from pacemaker diagnostics. Plasma levels of von Willebrand factor (vWf), tissue factor (TF), soluble P-selectin (P-sel) and D-dimer (DDM) were analysed using ELISA.

Results Baseline characteristics and co-morbidities were comparable between groups (Abstract 146 table 1). Patients with AHREs had significantly higher cumulative percentage ventricular pacing (p=0.012). There were no significant differences in levels of vWf, TF, P-sel and DDM between patients with and without AHREs. The AFB ranged from 0 to 99% in AHRE group. TF (r=0.516, p=0.086), P-sel (r=0.795, p<0.001) and DDM (r=0.643, p=0.045) correlated with AFB. On linear regression analysis, both P-sel and DDM were independently associated with AFB (p<0.05).

Conclusion AFB is independently associated with increased indices of P-sel and D-dimer which indicate platelet activation and thrombosis respectively.