Left Atrial Stiffness is Associated with Age-Related Decrease in Exercise Capacity in Healthy Aging

Left atrial (LA) function contributes essentially to left ventricular filling. LA function and exercise capacity decline with age. This study aimed to determine whether age-related changes in LA function contribute to the observed age-related decline in exercise capacity. This cross-sectional study analysed 231 healthy participants (age range 50–89, mean 67.9, SD 10.7 years, approximately 50% females in each decade) from the COmPLETE-Health cohort. Participants were free of exercise-limiting conditions, never smoked or had not smoked for at least 10 years, had no diabetes, blood pressure <160/100 mmHg and body mass index <30 kg/m2. Exercise capacity was determined using peak oxygen uptake (VO2peak) during cardiopulmonary exercise testing. LA function was assessed through speckle-tracing transthoracic echocardiography, measuring LA reservoir strain (LASr), conduit strain (LAScd) and contraction strain (LASct). Early diastolic peak mitral inflow velocity (E) and early diastolic peak mitral annular velocity (e') were obtained using pulsed-wave and tissue Doppler imaging, respectively. LA stiffness was calculated as E/e'/LASr. Multiple linear regression models were fitted for all LA functional parameters and analysed with ANOVA. Uncertainty due to missing data was accounted for by multiple imputation. LASr (F(3; 219) = 4.62, p = 0.004) and LAScd (F(3; 219) = 25.00, p < 0.0001) decreased with age, whereas LASct increased with age (F(3; 219) = 5.79, p = 0.0008). LA stiffness also increased with age (F(3; 213.8) = 14.06, p < 0.0001). Of all assessed parameters, only LA stiffness was inversely related with VO2peak, independent of age (F(3; 198.6) = 3.19, p = 0.024). In healthy middle-aged to elderly adults, increased LA stiffness was associated with decreased aerobic exercise capacity, independent of age; suggesting that LA stiffness may play a contributory role in the age-related decline of exercise capacity.