Innovative markers of left atrial remodeling in the prediction of exercise capacity in sarcomeric hypertrophic cardiomyopathy

Introduction In patients with sarcomeric hypertrophic cardiomyopathy (HCM), exercise limitation is frequent and multifactorial but mainly results from impaired stroke volume augmentation during exercise, due to diastolic dysfunction. Left atrial (LA) remodeling, reflecting elevated filling pressures and atrial myopathy, has been associated with adverse outcomes, but its association with functional capacity remains underexplored. Aim To assess the value of echocardiographic LA parameters, particularly the Left Atrial Stiffness Index (LASI = E/e’/LASr), the Left Atrial Coupling Index (LACI = LAVI/LASct) and the Left Atrioventricular Coupling Index (LAVCI = LAVmin/LVEDV) in predicting exercise capacity, as measured by peak oxygen consumption (VO2 peak), in a population of sarcomeric HCM. Materials and methods We conducted a retrospective, single-center study at a referral center for cardiomyopathies. Among 336 consecutive patients with sarcomeric HCM who underwent cardiopulmonary exercise testing (CPET) and transthoracic echocardiography, we analyzed LA volumetric and functional indices, including LA volume index (LAVI), LASI, LACI, LAVCI, LA emptying fraction (LAEF), and phasic strain (reservoir, conduit, and pump). Patients were stratified by VO2 peak tertiles (>80%, 60–80%, <60% predicted), and univariate logistic regressions were used to identify predictors of preserved exercise capacity. Results Ranked by strength of correlation, higher LAVCI, LASI and LACI values were significantly associated with lower VO2 peak (p < 0.001), as were reduced LA strain parameters and LAEF. Conversely, lower LAVCI, LASI and LACI values correlated with preserved exercise capacity. In univariate models, LA parameters outperformed conventional clinical and morphological predictors. Conclusion In sarcomeric HCM, LA dysfunction, captured by novel indices such as LASI, LACI and LAVCI, strongly correlates with impaired exercise capacity. These parameters may help refine functional risk stratification and patient management.