To characterize left atrial (LA) and left ventricular (LV) function and atrioventricular (AV) coupling in patients with moderate mixed aortic valve disease (MMAVD) against those with isolated moderate or severe aortic valve disease and controls. Retrospective LA and LV peak longitudinal strain (LS) analysis were performed on 260 patients (46 MMAVD, 81 moderate aortic stenosis (AS), 50 severe AS, 48 moderate aortic regurgitation (AR), and 35 severe AR) and 66 controls. Peak LV and LA LS and AV coupling, assessed by combined peak LA and LV strain, was compared between the groups. ANOVA and 2-sided t-tests were used and a p-value of <0.01 was considered significant.LV strain was significantly lower in those with MMAVD compared to controls and those with moderate or severe isolated AR but comparable to those with moderate or severe AS (-17.1±1.1% MMAVD vs. -17.7±1.5% moderate AS p=0.02; vs. -17.0%±1.5% severe AS, p=0.74). AV coupling was significantly lower in those with MMAVD compared to controls and those with moderate AS or AR but comparable to those with severe AS or AR (47.1±6.8% MMAVD vs. 45.1±5.6% severe AS, p=0.13; vs. 50.4±9% severe AR, p=0.07). Impairments in AV coupling are comparable for patients with MMAVD and those with severe isolated AS or AR. Impairments in LV GLS in MMAVD mirror those found in severe AS. These findings suggest that haemodynamic consequences and adverse remodelling are similar for patients with MMAVD and isolated severe disease.