Cryptogenic stroke, left atrial function, and atrial fibrillation: a complex relationship

Abstract Background Paroxysmal atrial fibrillation (AF) may underlie some embolic strokes of undetermined source (ESUS), but the widespread use of loop recorders (LRs) to detect it may not be cost-effective. This study evaluated whether assessing left atrial (LA) function by speckle tracking echocardiography (STE) could help to identify ESUS patients most likely to benefit from LR monitoring for AF detection. Methods Consecutive ESUS patients diagnosed between 2020 and 2023, who underwent LR implantation and comprehensive echocardiographic evaluation, including STE, were enrolled. Patients were divided into two groups based on AF detection by LR over a median follow-up of 10.0 months (IQR 6.0–21.7). Results A total of 64 patients were included: 27 (42.2%) with AF (AF group) and 37 (57.8%) without AF (No-AF group). Compared to the No-AF group, patients in the AF group showed a significantly larger left atrial volume index (LAVi: 44.7 ± 10.8 vs. 34.4 ± 8.3 mL/m 2 ; p < 0.001), a lower LA longitudinal strain of reservoir (LASr: 19.7 ± 8.9% vs. 27.4 ± 9.5%; p = 0.003) and contraction (LASct: 7.4 ± 6.5% vs. 12.4 ± 7.2%; p = 0.008), and an increased LA stiffness index (LASi: 0.6 ± 0.3 vs. 0.3 ± 0.2; p < 0.001). In multivariable Cox regression analysis, only LAVi and LASct remained independent predictors of AF. Conclusions LAVi and LASct appear useful and reliable predictors of AF occurrence during follow-up in ESUS patients and may aid in selecting those who are most likely to benefit from LR implantation. Graphical abstract