Luo X, et al. - Given long-term heart rate (HR) control is one management strategy for patients with chronic atrial fibrillation (AF) but the optimal target HR of AF patients is debated, researchers compared AF patients with controls with sinus rhythm (SR) with respect to HR at rest, during and after a 6-minute walk test (6WMT). Consecutive matched patients with AF or SR were recruited and 6MWT was performed. Five subgroups (<80bpm, 80-89bpm, 90-99bpm, 100-109bpm and ≥110bpm) were formed based on the resting HR. In AF patients, excessively increased HR was detected during 6MWT, with a delay noticed in HR recovery after 6MWT. These findings were especially documented when resting HR was >90bpm. As recommended, perhaps <90bpm be the optimal initial resting HR for AF patients.