Bridging the divide: left atrial reservoir strain as a predictor of outcomes in ventriculogenic and atriogenic mitral regurgitation

Abstract Background Secondary (functional) mitral regurgitation (SMR) confers increased morbidity and mortality, even in patients with relatively preserved left ventricular ejection fraction (LVEF). Left atrial reservoir strain (LASR), as measured by speckle-tracking echocardiography (STE), has emerged as a sensitive marker of LA remodeling and may offer incremental prognostic value. This study aimed to determine whether LASR predicts both all-cause mortality and heart failure admissions in moderate to severe SMR and assess its incremental utility over conventional parameters such as LA volume and LVEF. Methods We retrospectively examined 102 patients (mean age 68 ± 14 years, 41.2% female) with at least moderate SMR who underwent transesophageal echocardiography (TEE) between January 2018 and December 2023. Patients were categorized into VFMR (LV dysfunction or LV remodeling) and AFMR (LA enlargement with preserved LV function). Standard transthoracic echocardiography (TTE) measured LVEF, LV volumes, regurgitant volume (RV), and effective regurgitant orifice area (EROA). Two-dimensional STE was used to assess LASR from apical four- and two-chamber views. The primary endpoint was all-cause mortality; secondary endpoint was HF hospitalization. Cox proportional hazards models evaluated the association of LASR with outcomes. Patients were also stratified into risk categories by LASR quartiles and peak tricuspid regurgitation (TR) velocity. Results LASR emerged as an independent predictor of all-cause mortality (adjusted HR = 0.887, 95% CI: 0.791–0.994, p = 0.039), independently of the etiology of the mitral regurgitation (HR = 0.872, 95% CI: 0.793–0.960, p = 0.005). Kaplan-Meier analysis showed significantly better survival in higher LASR quartiles (log-rank p = 0.013). In combination with peak TR velocity, LASR distinguished high-risk and low-risk phenotypes more accurately, with high-risk patients (LASR ≤ 9.0% or peak TR velocity >3.0 m/s) displaying a threefold increased risk of mortality (HR = 2.853, p = 0.012) and a fourfold higher risk of HF admission (HR = 3.922, p = 0.029). Conclusions In patients with moderate to severe SMR, left atrial reservoir strain, particularly in combination with peak TR velocity, demonstrated robust predictive value for both mortality and HF hospitalization, independent of SMR etiology (VFMR or AFMR). This combined approach enhanced risk stratification, highlighting the critical role of LA functional assessment in optimizing patient management.