Impaired Left Atrial Reserve Function in Heart Failure With Preserved Ejection Fraction

BACKGROUND: Left atrial (LA) dysfunction is common in heart failure (HF) with preserved ejection fraction. However, data on the pathophysiologic impacts of impaired LA functional reserve remained limited. We sought to determine the association of abnormal LA dynamics during exercise with cardiovascular reserve, exercise capacity, and clinical outcomes. METHODS: Patients with HF with preserved ejection fraction (n=231) and controls without HF (n=219) underwent exercise stress echocardiography with simultaneous expired gas analysis. LA function was assessed at rest and during exercise using speckle-tracking echocardiography. RESULTS: Patients with HF with preserved ejection fraction demonstrated less increase in LA reservoir and booster pump strain during exercise than those in controls. The degree of LA dilation was more closely related to exercise LA reservoir strain than to resting LA strain (Meng test, P=0.002). The presence of impaired LA reservoir strain during exercise was associated with poorer biventricular systolic reserve and cardiac output augmentation, more severe right ventricular-pulmonary artery uncoupling, and lower peak oxygen consumption. Patients with a lower exercise LA reservoir strain had a 2.7-fold increased risk of HF events (hazard ratio, 2.66 [95% CI, 1.32–5.38]; P=0.006). Among patients with follow-up echocardiography, initiation of guideline-directed medical therapy or atrial fibrillation ablation showed significant improvements in LA reservoir (P<0.001 and P=0.022) and booster pump strain (P=0.011 and 0.028) at rest and during exercise, respectively. CONCLUSIONS: Impaired LA reservoir function during exercise in HF with preserved ejection fraction is associated with biventricular reserve limitations, exercise intolerance, and increased risks of HF events.