Fig. 2

ECG traces during the study. A: Control horse in SR at day 0 and at day 55 (B). C: Manual burst-pace at day 0 resulted in short AF episodes followed by SR. Arrow head indicate the first P wave after spontaneous cardioversion. D: Pacemaker driven atrial rhythm of 170 min^− 1 (352 ms) with intermittent AV block. E and F: One horse in AF at day 1 and day 55, respectively. Note the faster fibrillatory rate at day 55 (F). Paper speed 10 mm/s, gain 10 mm/mv