Left atrial stiffness in patients with severe aortic stenosis: a novel approach

Abstract

Abstract Background Left atrial (LA) stiffness index is a non-invasive transthoracic echocardiography (TTE) measure that combines left ventricle filling pressure (E/e’) and LA strain at reservoir (LAS_r)(1-3). LAS assessment using cardiac magnetic resonance feature tracking (CMR-FT) is feasible and reproducible(4, 5), and may have advantages over TTE. CMR-modelled pulmonary capillary wedge pressure (PCWP) has recently been validated and shown to be of prognostic value in heart failure(6). We investigate the feasibility of assessing LA stiffness index using novel approaches (CMR and hybrid TTE and CMR) in patients with severe aortic stenosis (AS) compared to controls. Method Patients with severe AS and matched controls were prospectively recruited. CMR and TTE scans were performed on the same day. LAS_r was assessed on 4- and 2-chamber long-axis images, and average value was calculated. Images were analysed using TomTec-ARENA (v2.4) for speckle tracking echocardiography (STE), whereas Medis Suite (v3.1) was used for FT-CMR by a blinded single observer. CMR-modelled PCWP was calculated as: 6.1352 + (0.07204 ∗ LAV) + (0.02256 ∗ LVM), where LAV=left atrial maximum volume and LVM=left ventricle mass by CMR(6). LA stiffness index calculated by (i) TTE: E/e’/LAS_r, using LAS by STE; (ii) TTE-CMR hybrid: E/e’/LAS_r, using LAS by FT-CMR; (iii) CMR: CMR PCWP/LAS_r, using LAS by FT-CMR (Figure). Result Patients with severe AS (n=78, mean age 67.1±9.4 years; 74% males) were well matched to the controls (n=19) for demographics and body size. Patients demonstrated significantly higher filling pressures, lower LAS, higher LAV and LVM. All measures of LA stiffness were significantly higher in patients with AS than matched controls (Table). The correlation between TTE and CMR measured LA stiffness was fair (r=0.46, p-value <0.001), moderate between CMR and TTE-CMR hybrid (r=0.71, p-value <0.001) and strong correlation between TTE and TTE-CMR hybrid (r=0.86, p-value <0.001). Conclusion Non-invasively estimated LA stiffness obtained by TTE, CMR or hybrid are feasible in patients with severe AS, and demonstrates higher stiffness index compared to matched controls.Table 1Figure 1