Changes in left atrial reservoir function and their association with exercise capacity after outpatient cardiac rehabilitation in early-stage heart failure with preserved ejection fraction

Background Cardiac rehabilitation (CR) improves exercise capacity in patients with heart failure with preserved ejection fraction (HFpEF). Nonetheless, changes in left atrial (LA) mechanics after outpatient CR and the link between changes in LA function and exercise capacity in early-stage HFpEF remain unclear. Therefore, we aimed to examine changes in LA reservoir function after outpatient CR and its association with exercise capacity in early-stage HFpEF. Methods Echocardiography and cardiopulmonary exercise testing were performed pre- and post-CR in 21 patients with early-stage HFpEF without prior HF hospitalization (median age: 80 years; median HFA-PEFF score: 4). Exercise capacity was assessed by peak oxygen uptake (VO2). Left ventricular global longitudinal strain (LV-GLS) and LA reservoir strain (LASr) were derived using speckle-tracking echocardiography. Early diastolic mitral inflow velocity to mitral annular velocity (E/e′) ratio was measured. LA stiffness index was calculated as the ratio of E/e′ to LASr. Results Peak VO2 (13.3 ± 3.7 to 15.0 ± 3.8 mL/kg/min, p < 0.001) and LASr (20.4 ± 7.3 to 24.2 ± 6.9%, p = 0.002) significantly increased after outpatient CR. The peak VO2 change rate correlated with the LASr and LA stiffness index change rates (r = 0.62, p = 0.003; r = − 0.53, p = 0.017, respectively), but not with the LV-GLS change rate (r = 0.08, p = 0.735). LASr change rate continued to be associated with the peak VO2 change rate after multivariable adjustment in exploratory models. Conclusions In early-stage HFpEF, LA reservoir function increased after outpatient CR, and changes in LA reservoir function were independently associated with changes in exercise capacity.