Left atrial remodeling may compensate for changes in cardiac structure, function
Remodeling of the left atrium continues into middle and old age as a form of haemodynamic compensation for alterations in the structure and function of the heart, according to a study presented at the recently concluded 21st Asian Pacific Society of Cardiology Congress (APSC 2017).
“There may also be a cohort effect as indicated in the difference between longitudinal and cross-sectional observations,” researchers wrote.
The study included 407 disease-free participants from the fourth (mean age 67.57±9.012 years) and fifth (mean age 72.03±9.007 years) follow-ups of the Multi-Ethnic Study of Atherosclerosis (MESA). Only those who underwent cardiac magnetic resonance imaging (cMRI) were eligible for inclusion.
“This study evaluated age-related changes in [left atrial] volume and function during a longitudinal observation of a large cohort of asymptomatic individuals, who were free of clinical cardiovascular disease,” they said.
From MESA 4 to MESA 5, a significant decrease in the minimum left atrial volume was observed (18.28±7.44 vs 17.52±8.91 mL/m2; change, -0.76; p=0.04). There was no significant change in maximum left atrial volume (36.79±11.2 vs 36.04±11.9 mL/m2; change, -0.75; p=0.16). [APSC 2017, abstract MP-04]
In contrast, both minimum (p<0.05) and maximum (p<0.05) left atrial volumes showed significant cross-sectional increases with age.
Similarly, both passive (20.65±7.37 vs 21.09±7.84 percent; change, 0.44; p<0.001) and active (38.53±9.52 vs 40.76±11.0 percent; change, 2.23; p<0.001) left atrial ejection fractions increased significantly from MESA 4 to MESA 5.
Cross-sectional data showed that, while passive ejection fraction showed significant decreases (p<0.001), active ejection fraction did not change (p=0.55).
Longitudinal univariate analysis of the cohort with respect to age revealed that left atrial total ejection fraction had a positive delta change at 50 years old and a negative delta change at >85 years old. Active ejection fraction of the left atrium showed a similar trend.
According to the researchers, these findings indicate that there is a “continual [left atrial] remodeling in middle age and the elderly.” These mechanisms help compensate for cardiac changes.
“Patients above 85 years may have decompensation of the left atrium,” they added.
Between MESA 4 and 5, there were significant decreases in diastolic blood pressure (p<0.001), current (p<0.001) and former smokers (p<0.001), and high-lipoprotein cholesterol (p<0.001). On the other hand, pulse pressure (p<0.001) and diabetes incidence (p<0.001) increased significantly.
In the study, cMRI was used to measure changes in maximum and minimum volumes of the left atrium, and passive and active ejection fractions, with measurements indexed to body surface area. Student’s T-test and Pearson’s correlation were used to determine longitudinal and cross-sectional changes in left atrial measurements, respectively.