Atrial fibrillation and platelet reactivity.

BACKGROUND The impact of atrial fibrillation (AF) upon platelet reactivity has not been investigated. METHODS Subjects were 33 individuals with AF who consented to elective electrical cardioversion (ECV) immediately before ECV determination of surface-bound fibrinogen after stimulation i.e. platelet reactivity was carried out. A flow cytometer was employed. ADP (1.7 and 8.5 μmol/L) and a thrombin receptor activating peptide (54 and 74 μmol/L) were used as agonists. The analyses were repeated after 26±8(SD) months. RESULTS Compared to day 1 subjects with AF (n=18) had a trend towards lower platelet reactivity at study end. It reached significance when using 1.7 μmol/L ADP. In contrast, after 26±8(SD) months sinus rhythm (SR) (n=15) was associated with significant lower reactivity with all agonists. CONCLUSION After 26±8(SD) months patients returning with AF had higher platelet reactivity than those who remained with SR.