The Influence of Transcatheter Aortic Valve Replacement on Left Atrial Mechanics: A Systematic Review and Meta-Analysis

Background The morphology and function of the left atrium (LA) are intimately tied to left ventricular loading conditions. Data pertaining to the effect of transcatheter aortic valve replacement (TAVR) on LA function and geometry are scarce. Objectives To quantify associations between TAVR and LA remodelling by pooling available data from published observational studies. Methods A systematic review and meta-analysis were performed. Eligible studies needed to report serial LA STE data, before and after TAVR. Other outcome data included LA area and indexed volume (LAVi) and standard chamber measurements. Outcomes were stratified by timing of follow-up echocardiography: early (<6mo) or late (≥6mo). Results Twelve studies were included, comprising 1,066 patients. The mean overall reduction in LAVi was 2.72mls/m 2 following TAVI (95% CI 1.37-4.06, p <0.01, low heterogeneity: I 2 = 0%). LA reservoir function improved overall by a mean difference of 3.71% (95% CI 1.82-5.6, p<0.01), though there was significant heterogeneity within the pooled studies (I 2 = 87.3%). Significant improvement in reservoir strain was seen in both early follow up (MD 3.1%, p<0.01) and late follow up studies (MD 4.48%, p=0.03), but heterogeneity remained high (I 2 = 65.23% and 94.4%, respectively). Six studies reported change in LA booster/contractile function, which recovered in the early follow-up studies (MD 2.26, p<0.01), but not in the late group (MD 1.41, p=0.05). Pooled improvement in LA booster function was 1.96% (95% CI 1.11-2.8, p<0.01, low heterogeneity: I 2 = 0%). Conclusion The afterload reduction afforded by TAVR is associated with significant haemodynamic and morphological up-stream LA changes. Condensed Abstract The morphology and function of the left atrium (LA) are intimately tied to left ventricular loading conditions. LA function, measured with speckle-tracking echocardiography (STE), has been demonstrated to provide independent prognostic information for a range of cardiomyopathic states and valvular diseases. We sought to better understand the effect of transcatheter aortic valve replacement (TAVR) on LA function and geometry by performing a systematic review and meta-analysis. Key findings are that, following TAVR, the left atrium negatively remodels (reduces in size), and this is associated with improved distensibility, as quantified by an improvement in reservoir function.