B-po01-019 coagulation potential, electrophysiological characteristics and structural remodeling due to atrial fibrillation in young and aged goats

Age is a risk factor for atrial fibrillation (AF) as well as for stroke in patients with AF. The effect of ageing on AF mechanisms and on coagulation activity is not well understood. To evaluate the effect of age and AF on coagulation activity, AF characteristics, and structural remodeling. Four groups of goats were investigated: Young sham (Y-Sh: sinus rhythm, <3 years old, n=9), Young AF (Y-AF: 4 weeks of AF, <3 years old, n=7), Old sham (O-Sh: sinus rhythm, >8 years old, n=6), and Old AF (O-AF, 4 weeks of AF, >8 years old, n=8). Groups were matched for body weight. AF was maintained using implantable pacemakers in both AF groups. Clotting potential was measured using tissue factor-induced thrombin generation (TG) assays at baseline and 4 weeks (final). A terminal experiment was performed with atrial contact mapping to study electrophysiological AF characteristics and to collect atrial tissue for histological analysis. The clotting potential, expressed as the ability of activated plasma to generate thrombin, did not differ among groups. However, AF in old goats caused an increase in coagulation potential (thrombin nM) while this was not the case in young goats. Complexity of fibrillatory conduction (no. of waves) was higher in AF groups after 4 weeks as compared to Sham, but there was no effect of age. AF-related atrial myocyte hypertrophy occurred in old but not in young goats. Endomysial fibrosis was similar in all groups. Four weeks of AF caused an increase in clotting potential and myocyte size in old but not in young goats. Age did not cause fibrosis or increased AF complexity.