February 3, 2021Open Access

Impaired Left Atrial Performance Resulting From Age-Related Arial Fibrillation Is Associated With Increased Fibrosis Burden: Insights From a Clinical Study Combining With an in vivo Experiment

KLKaibin LinGuangdong Ocean University KCKankai ChenShanghai Sixth People's Hospital SLShuai LiEast China University of Technology

Structured PICO

Do physiological aging and persistent atrial fibrillation synergistically impair left atrial performance and increase fibrosis burden?

Population

132 control individuals (supraventricular tachycardia with left accessory pathway, severe vasovagal syncope, or lone premature atrial contractions) and 117 patients with persistent atrial fibrillation, stratified into three age groups (<65 years, 65-79 years, >80 years). An animal study cohort of 15 young (3 months) and 15 aged (27 months) mice was also included.

Comparator

Control individuals without atrial fibrillation, and young mice compared to aged mice.

Outcome

Alterations in left atrial (LA) function (LA dimension, LA stiffness index, LA global longitudinal strain, LA strain rates) measured by two-dimensional speckle tracking echocardiography, and LA fibrosis burden (mean LA voltage, LA surface area, low-voltage area %, LA volume) measured by electroanatomic mapping.surrogate

Physiological aging and persistent atrial fibrillation independently and synergistically contribute to left atrial structural remodeling, functional impairment, and increased fibrosis burden.

Abstract

Background: Atrial fibrillation (AF) is increasingly considered an age-related degenerative disease, whose process is associated with the development of impaired left atrial (LA) performance. However, the subtle dynamic changes of LA performance in AF during aging have yet to be fully elucidated. Atrial fibrosis is a key substrate for the development of AF, but the progression of fibrosis during aging and its relationship with LA dysfunction need to be further explored. Methods: A total of 132 control individuals and 117 persistent AF patients were prospectively studied. Subjects were further stratified into three age groups (age group 1: younger than 65 years, age group 2: between 65 and 79 years old, and age group 3: older than 80 years). The two-dimensional speckle tracking imaging was carried out for analyzing the alterations in LA function underlying LA remodeling, whereas electroanatomic mapping was performed to investigate LA fibrosis burden. In animal study, aged mice and young mice served as research subjects. Echocardiography and histological staining were used to assess LA performance and fibrosis burden, respectively. Results: Echocardiography showed progressive increases in LA dimension and LA stiffness index, and progressive decreases in LA global longitudinal strain and LA strain rates with advancing age in both AF and control cohorts, which was more prominent in AF cohort. Electroanatomic mapping showed progressive decrease in mean LA voltage and progressive increases in LA surface area, low-voltage area %, and LA volume with advancing age, whereas more significant alterations were observed in AF patients. Moreover, left atrial global longitudinal strain was positively correlated with mean LA voltage, whereas LA stiffness index was negatively related to mean LA voltage. In animal experiment, increased LA size and pulmonary artery dimension as well as longer P-wave duration and more prominent LA fibrosis were found in aged mice. Conclusions: This study provides new evidence of subtle changes in structure and performance of left atrium and their association with atrial fibrosis in both AF and non-AF subjects during physiological aging. In addition, our study also provides normal values for LA structure and performance in both AF and non-AF conditions during aging. These measurements may provide an early marker for onset of AF and LA adverse remodeling.

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