Objective To analyze the ambulatory electrocardiographic characteristics of atrial fibrillation( AF) with slow ventricular rate and to explore its mechanism. Methods Slow ventricular rate referred to the average ventricular rate < 60 times/min and the fastest ventricular rate < 90 times/min. Combining with clinical data,retrospective analysis was performed on ambulatory electrocardiography( AECG) of 27 AF patients with slow ventricular rate. The frequency and distribution state of long RR interval( > 2. 0 s...