Abstract 1383: Aging Affects the Response of the Left Atrium to Adrenergic Stress
Introduction: Aging reduces the contractile response of the left ventricle (LV) to adrenergic stress. Although left atrial (LA) dimensions increase with age, it is unknown whether aging impedes stress induced changes in LA volumes and LA ejection fraction (EF).
Hypothesis: We hypothesized that aging may reduce LAEF during dobutamine stress.
Methods: We enrolled 205 participants referred for dobutamine stress cardiovascular magnetic resonance (DCMR) and measured LA volumes from a 3-dimensional cine white blood multi-slice, multi-phase acquisition before and during DCMR. LA maximal and minimal volume, and LAEF [defined as LA (maximal- minimal/maximal) volume] were manually drawn using CAAS-MRV software (Pie Medical Imaging, Netherlands). LAEF measures both LA conduit and active emptying fraction. All volumes were indexed to body surface area.
Results: Participants were 68±7 years of age; 53% were men; 26% had coronary artery disease, 37% had diabetes, 91% had hypertension, and 9% had atrial fibrillation. Increasing age correlated inversely with LAEF and positively with LA volumes (Figure⇓). Linear regression analysis revealed that age was an independent predictor of LAEF during low dose (B=−0.164, p=0.02) and peak dose (B=−0.261, p <0.001) dobutamine stress, after adjusting for LVEF, diabetes, hypertension, coronary artery disease, gender and atrial fibrillation.
Conclusion: Age is associated with increased LA volumes and decreased LAEF at rest and during dobutamine stress. Further studies are needed to differentiate and understand the effects of aging on LA conduit and active emptying fraction.