Non-invasively estimated left atrial stiffness is associated with short-term recurrence of atrial fibrillation after electrical cardioversion

Background: As atrial stiffness (K_la) is an important determinant of cardiac pump function, better mechanical characterization of left atrial (LA) cavity would be clinically relevant. Pulmonary venous ablation is an option for atrial fibrillation (AF) treatment that offers a powerful context for improving our understanding of LA mechanical function. We hypothesized that a relation could be detected between invasive estimation of K_la and new non-invasive deformation parameters and traditional LA and left ventricular (LV) function descriptors, so that K_la can be estimated non-invasively. We also hypothesized that a non-invasive surrogate of K_la would be useful in predicting AF recurrence after cardioversion.

Methods: In 20 patients undergoing AF ablation, LA pressure-volume curves were derived from invasive pressure and echocardiographic images; K_la was calculated during ascending limb of V-loop as ΔLA pressure/ΔLA volume. 2D-speckle-tracking echocardiographic LA and LV longitudinal strains and volumes, ejection fraction (EF) and ventricular stiffness (K_lv), as obtained from mitral deceleration time, were tested as non-invasive K_la predictors. In 128 sinus rhythm patients 1 month after electrical cardioversion for persistent AF, non-invasively estimated K_la (computed-K_la) was tested as predictor of recurrence at 6 months.

Results: Tertiles of mean LA pressure correlated with increasing K_la (trend, p=0.06) and decreasing LA peak strain, LVEF, and LV longitudinal strain (p=0.029, p=0.019, and p=0.024). There were no differences in LA and LV volumes and K_lv across groups. Multiple regression analysis identified LV longitudinal strain as the only independent predictor of K_la (p=0.014). Patients in highest quartile of computed-K_la (estimated as [log]=0.735+0.051×LV strain) tended to have highest AF recurrence rate (25%) as compared with remaining 3 quartiles (9%, 9%, 3%, p=0.09).

Conclusion: K_la can be assessed invasively in patients undergoing AF ablation and it can be estimated non-invasively using LV strain. AF recurrence after cardioversion tends to be highest in highest quartile of computed-K_la.