Left atrial (LA) reservoir function is an important determinant of left ventricular (LV) filling. While atrial fibrillation (AF) has been suggested to impair LA function, the impact of atrial fibrillation on left atrial reservoir function, in comparison with normal sinus rhythm (NSR), has not been fully elucidated

We studied 40 patients with AF and 42 with NSR, matched for age and maximum LA volume. Echocardiographic measurements included maximum and minimum LA volume, LA reservoir volume, stroke volume, LA reservoir strain (LAS), and LV global longitudinal strain (GLS). The standard apical four-chamber view was used for speckle-tracking LAS analysis

Maximum LA volume was comparable between AF and NSR groups (99.6 vs. 97.7 mL, ns). However, reservoir volume was significantly lower in AF (19.1 vs. 37.4 mL), and reservoir fraction was markedly reduced (25.1 vs. 97.6%). Minimum LA volume was higher in AF (80.5 vs. 60.6 mL), showing an inverse relationship with reservoir fraction. Reservoir volume correlated with stroke volume in both groups. LAS was lower in AF compared with NSR (8.0 vs. 17.6%), while its dependence on GLS was attenuated in AF. The standard deviation of peak strain timing across six LA segments was greater in AF (95 vs. 64 ms), indicating dyssynchronous LA expansion

AF is associated with impaired LA reservoir function. This impairment is not attributable to chamber size but rather to dyssynchronous relaxation of the atrial wall and attenuated influence longitudinal LV contribution