Prognostic Role of Left Atrial Reservoir Strain for Risk Stratification in Aortic Stenosis: A Systematic Review

Background: Risk stratification in aortic stenosis (AS) remains challenging, particularly in patients with preserved left ventricular ejection fraction or inconclusive symptom status, as conventional parameters primarily reflect valvular obstruction and may underestimate the extent of cardiac dysfunction. Left atrial reservoir strain (LASr) has emerged as a promising and potentially more comprehensive marker of atrial function and diastolic burden, with potential prognostic implications. Methods: A systematic review was conducted in accordance with PRISMA guidelines. PubMed, Scopus, and EMBASE were searched from inception to April 2026. Studies including adult patients with moderate or severe AS and evaluating LASr using different imaging modalities (speckle-tracking echocardiography, cardiac computed tomography, or cardiac magnetic resonance) were considered eligible if clinical outcomes were reported. Data were qualitatively synthesized, and continuous variables were summarized as weighted medians with interquartile ranges. Results: Twenty-one studies were included, encompassing a large and clinically heterogeneous population. During follow-up, a substantial proportion of patients experienced adverse events, including mortality, heart failure hospitalization, arrhythmic events, and composite cardiovascular outcomes. Across studies, reduced LASr consistently emerged as a significant predictor of adverse outcomes. This association was observed both when LASr was analyzed as a continuous variable and when defined using study-specific cut-off values, which generally clustered within a relatively narrow range. Importantly, LASr demonstrated incremental prognostic value beyond conventional echocardiographic parameters, including left atrial size, left ventricular ejection fraction, global longitudinal strain, and indices of diastolic dysfunction. The prognostic relevance of LASr was consistent across different imaging modalities, including both echocardiography and cardiac computed tomography (with no eligible studies using cardiac magnetic resonance). Conclusions: LASr is a robust and reproducible marker of adverse prognosis in patients with AS, reflecting the cumulative burden of left-sided pressure overload and atrial remodeling. Its integration into multiparametric assessment may enhance risk stratification and support more individualized clinical decision-making. Further prospective studies are warranted to standardize measurement techniques and define clinically actionable thresholds.