Abstract Body (Do not enter title and authors here): Background: Left atrial (LA) dysfunction is common in heart failure with preserved ejection fraction (HFpEF), but the extent to which LA dysfunction impacts cardiac performance during exercise is unknown. Given the importance of the LA for ventricular filling, we assessed the relationship between LA compliance (LAc) at rest and during exercise and exercise stroke volume (SV) generation.

Methods: We studied 50 adults with HFpEF during rest and upright cycle exercise (20W). LA volumes were calculated from two-dimensional, 4-chamber and 2-chamber echocardiographic views during both stages. LA pressures were derived from v-wave maximal amplitudes of corresponding pulmonary capillary wedge pressure tracings. LAc was calculated as LA volume divided by LA pressures (mL/mmHg).

Results: LA volume increased by 3.5+1.4mL (p<0.01), LA compliance decreased by 4.2+5.3 mL/mmHg (p<0.001), and SV increased by 28.9+13.4mL (p<0.001) from rest to 20W exercise. Resting LAc was not associated with changes in SV (R²=0.01, p=0.47). LAc at 20W was statistically associated, albeit weakly, with changes in SV (p<0.04, R²=0.11). Only 2 patients improved/increased LAc and there was no relationships between LA compliance changes and SV changes during rest and exercise (p=0.93).

Conclusions: LAc decreased with exercise in patients with HFpEF. LAc measured at 20W had a weak relationship with SV response but changes in LAc did not discriminate for individual SV responses. These findings suggest that LAc does not contribute to SV generation during exercise in patients with HFpEF.