Fig. 1.

Study design. Study start at day 0, three weeks after pacemaker implantation. Baseline measurements were performed in sinus rhythm (baseline SR) before atrial fibrillation (AF) induction and 24 h after pacing was initiated (day 1, baseline AF). Pacing continued until self-sustained AF. Experimental protocol included electrocardiography (ECG), echocardiography, atrial fibrillatory rate recordings (AF group) and flecainide administration. Cardiac tissue was harvested at the end of the study