Abstract Body (Do not enter title and authors here): Background: Left atrial (LA) strain is an established marker of LA function. Our previous meta-analysis (Pathan, 2017) from 2,542 healthy subjects reported 39.4% with lower limit of normal (LLN) at 38.0%. However, subsequent original studies revealed much lower LLN, ranging from 15.1% to 28.2% (Figure). The LLN is critically important for clinical practice to distinguish abnormal LA function from normal. Thus, we hypothesised that a Bayesian meta-analysis to pool LLN from healthy individuals would determine a clinically meaningful cut-off threshold for LA strain.
Aim: As there has been a large number of recent studies reporting normal LA strain since 2017, we aimed to update our systematic review and run Bayesian analysis for LLN of LA strain.
Methods: Following PRISMA Guidelines, an updated systematic review was conducted by searching PubMed, Embase, and Scopus databases. Studies of LA strain were included if they involved >20 healthy patients without cardiac disease or risk factors between 2016 and September 2022. Mean LA reservoir strain with 95% confidence intervals were extracted from eligible studies. We use Bayesian meta-analysis to pool the lower 95% confidence interval of the LA reservoir strain from included studies. Prior to pooling the result, we standardised the data with log transformation. The priori used in this model was based on weak informative prior with N (0,1) as the prior distribution. The posterior mean was then exponentiated to obtain the lower reference value and its 95% credible interval (CI).
Results: Sixty-three studies (10,533 healthy patients) satisfied inclusion criteria. Our updated Bayesian Meta-analysis demonstrated a pooled mean of 37.8% [95% CI: 36.1, 39.4] with LLN at 22.4% [20.6, 24.3], which is more concordant with recent original studies (Figure).
Conclusions: The normal mean LA strain has been updated by pooling >10,000 subjects. The updated LLN of 22.5% may represent a better clinical cut-off for normal LA strain to identify individuals with abnormal LA strain.