1350540 - Effect of aortic valve replacement on left atrial stiffness assessed by cardiac magnetic resonance imaging

Non-invasively measured left atrial (LA) stiffness is a novel transthoracic echocardiography (TTE)-derived measure that combines left ventricle filling pressure (E/e’) and LA strain at reservoir (LAS-r)(1-3). LAS assessment is feasible and reproducible by cardiac magnetic resonance (CMR) imaging(4, 5). We aimed to investigate (i) the feasibility of assessing LA stiffness index using LAS derived from feature tracking-CMR (FT-CMR) in patients with severe aortic stenosis (AS), and (ii) the effect of aortic valve replacement (AVR) on this novel imaging biomarker. 

Methods:

We prospectively recruited 78 Patients with severe AS scheduled for AVR and 19 matched controls. CMR and TTE scans were performed on the same day, pre- and a median of 6 months post-AVR.  Non-invasively estimated LA stiffness index was calculated as a ratio of E/e’ (by TTE) and LAS-r by FT-CMR (QStrain v2.0, Medis v3.1). LAS corresponding to reservoir function was assessed on 4- and 2-chamber long-axis standard steady-state free precession cine images, and average values calculated (Figure). In addition, LA volumes (maximum and minimum) were quantified using biplane area-length method. Image analysis was conducted by a blinded single observer.

Results:

Of the patients with severe AS, 52 (mean age 66.2±9.5 years; 76.9% males, had matched pre- and post-AVR LA stiffness ratio available. They were well matched to the controls for demographics and body size.  As shown in the Table, at baseline, patients with AS had significantly higher LA volumes, lower LAS-r, higher filling pressures and higher LA stiffness ratio compared to controls. Post-AVR, there were no significant changes in the LA volumes or strain, but there was a significant reduction in LA stiffness index (from 0.66 ± 0.49 to 0.51 ± 0.34 p=0.002) driven by a drop in filling pressure (E/e’). However, LA stiffness remained markedly higher than controls post-AVR.

Conclusion:

Non-invasively estimated LA stiffness obtained by FT-CMR is feasible in patients with severe AS, confirming increased stiffness index compared to matched controls. Following AVR, LA stiffness index was significantly reduced, driven by a reduction in filling pressure, but remained markedly elevated compared to controls.