Hwang JK, et al. - Researchers tested the hypothesis that frequent atrial premature complexes (APCs) during exercise provides prognostic information. Study participants were grouped by whether or not they had frequent APCs during treadmill testing (>5 beats per stage), with 128 in the FAPC group vs 870 in the non-FAPC group. New-onset atrial fibrillation or flutter (AF/AFL) during follow-up period (356.2 ± 131.1 days) was the primary outcome. The development of AF/AFL was linked to frequent APCs during treadmill testing and the need for close monitoring for further AF/AFL development was understood. Independent risk factors that predicted new-onset AF/AFL included treadmill-induced frequent APCs, chronotropic incompetence, and palpitation as a reason for treadmill testing.