Impaired left atrial strain is associated with new-onset atrial fibrillation and adverse clinical outcomes in primary care patients.

Background: Atrial fibrillation (AF) is linked to adverse left atrial (LA) remodeling, including fibrosis and mechanical dysfunction. LA strain is an imaging marker of atrial function that may improve risk stratification for AF, but its predictive and prognostic value in the primary care population remains unclear. Objective: This study aimed to evaluate whether LA strain is associated with new-onset AF and adverse clinical outcomes after AF diagnosis. Methods: We performed a 2-part study within a longitudinal primary care cohort (2001-2019). In a nested case-control analysis, 216 patients with new-onset AF were compared with 216 age- and sex-matched controls. LA strain parameters, including peak atrial longitudinal strain (PALS), peak atrial contractile strain, and LA conduit strain (LACS), were measured using speckle-tracking echocardiography before AF onset. In 127 patients with new-onset AF, Cox models examined associations between LA strain and all-cause mortality, stroke, myocardial infarction, and heart failure hospitalization. Results: Lower PALS and LACS were independently associated with more than 3-fold higher odds of AF (both Conclusion: In a primary care cohort, impaired LA strain was independently associated with new-onset AF and adverse outcomes after AF diagnosis, supporting its role in AF risk stratification.