Both beat-to-beat changes in RR-interval and left ventricular filling time determine ventricular function during atrial fibrillation.

Aims: The irregular atrial electrical activity during atrial fibrillation (AF) is associated with a variable left ventricular (LV) systolic function. The mechanisms determining LV function during AF remain incompletely understood. We aimed at elucidating how changes in RR-interval and LV preload affect LV function during AF.