Changes in left atrial size and function early after cardiac resynchronization therapy as assessed by conventional two-dimensional echocardiography

Aims: Cardiac resynchronization therapy (CRT) was shown to improve left atrial (LA) size and function within months after the procedure. We aimed to assess the impact of CRT on left atrial (LA) size and function within days after the procedure.  Materials and methods: Twenty-eight consecutive patients with CRT were evaluated before the procedure and within 3 days afterwards, and 25 of them were also examined at three months. Echocardiography was performed to assess LA size and function: LA volumes indexed to body surface (LAVIs) were measured at different moments during the cardiac cycle: ventricular end-systole – maximum LAVI (LAVImax), before atrial systole (LAVIpreA), and at ventricular end-diastole – minimum LAVI (LAVImin). These measurements were further used to calculate LA function parameters: LA total emptying fraction, active emptying fraction and passive emptying fraction. Results: LAVImax decreased within days after the procedure – 45.5 mL/ m2 (38.2-56.7) vs. 42.9 mL/m2 (32.1- 56.2), p <0.05, as did LAVImin – 27.1 mL/m2 (22.9-41.9) vs. 25.9 mL/m2 (17.8-38.1), p <0.05, and LAVIpreA – 40.0 mL/m2 (31.3-53.0) vs. 35.5 mL/m2 (25.8-49.1), without significant changes in functional parameters. All LAVIs were correlated to the diastolic filling time/RR interval ratio after CRT, but not before. Conclusions: LAVIs may be reduced within days after the implant procedure in responders to CRT, while atrial functional parameters remain unchanged. Correlations beween LAVIs and the diastolic filling time/RR interval ratio after CRT suggest that early optimization of atrio-ventricular and ventriculo-ventricular delays may have a positive and immediate impact on LA size.