Echocardiography flags silent paroxysmal atrial fibrillation in older adults

Researchers report that two non-invasive echocardiographic measures — the left atrial stiffness index (LASI) and left atrial activation time (LA-AT) — were significantly elevated in older adults with newly diagnosed, symptomatically silent paroxysmal atrial fibrillation (PAF) compared with age-matched controls. The findings, published open access in Cardiovascular Ultrasound, come from a retrospective analysis of participants in the STROKESTOP2 study and suggest that early atrial remodeling may be detectable even before the left atrium becomes structurally enlarged.

The study enrolled individuals with newly diagnosed PAF and a randomly selected age-matched control group without atrial fibrillation, all drawn from the STROKESTOP2 cohort. Every participant had an NT-proBNP level between 125 and 900 ng/L, a range indicating mild elevation rather than overt heart failure. Transthoracic echocardiographic examinations were analyzed retrospectively offline using dedicated software. In addition to conventional measurements, LA-AT was obtained by measuring the time delay between the onset of the P-wave on the electrocardiogram and the tissue Doppler Á peak wave in the lateral left atrial wall.

The cohort had a mean age of 76 ± 0.3 years. The PAF group comprised 67 participants, while the control group comprised 94. Patients with silent PAF showed a significantly higher LASI, with a median of 0.41 (interquartile range 0.29–0.60) versus 0.32 (0.29–0.43) in controls, P = 0.001. Left atrial activation time was also prolonged, at 170 ms (140–180) versus 140 ms (120–144), P < 0.001. These differences indicate both increased passive stiffness of the atrial chamber and delayed electrical conduction across the lateral atrial wall in the fibrillation group.

A key subgroup analysis strengthened the signal. Among participants whose left atrial volume index (LAVI) remained within normal limits at ≤ 34 ml/m², LASI and LA-AT were still significantly increased and prolonged in the PAF group (n = 27) compared with controls (n = 72). This suggests the echocardiographic markers capture functional and conduction changes that precede measurable structural enlargement of the atrium, a stage at which standard size-based screening criteria would appear normal.

Notably, NT-proBNP levels did not differ between the PAF group (228 ng/L, interquartile range 181–348) and controls (216 ng/L, 156–317), with P = 0.18. The biomarker therefore did not separate the two groups in this mildly elevated range, whereas the echocardiographic indices did. Receiver operating characteristic (ROC) curve analysis identified discrimination thresholds of LASI > 0.54 and LA-AT > 139 ms for identifying silent PAF in this population.

The authors conclude that indices reflecting left atrial stiffness and atrial conduction delay were significantly elevated in recently diagnosed PAF patients, and that LASI and LA-AT thresholds might non-invasively detect early atrial remodeling without structural enlargement in elderly patients at high risk of PAF who have mildly increased NT-proBNP levels. Because the analysis was retrospective and confined to a specific older, screened population with a defined biomarker range, the reported thresholds would require validation in other cohorts before any clinical use. The study was published as an accepted manuscript shared early for faster access; it is citable under a permanent DOI and subject to further editorial processing before the final version of record appears.

Subject of Research: Echocardiographic markers of left atrial stiffness and conduction delay in silent paroxysmal atrial fibrillation

Article Title: Echocardiographic markers for left atrial stiffness and left atrial conduction delay in patients with silent paroxysmal atrial fibrillation compared to age-matched controls

Article References: Bastos, L., Al-Khalili, F., Bäck, M., Manouras, A., Engdahl, J., & Shahgaldi, K. (2026). Echocardiographic markers for left atrial stiffness and left atrial conduction delay in patients with silent paroxysmal atrial fibrillation compared to age-matched controls. Cardiovascular Ultrasound. https://doi.org/10.1186/s12947-026-00395-1

Image Credits: AI Generated

DOI: 10.1186/s12947-026-00395-1

Keywords: atrial fibrillation, echocardiography, left atrial stiffness index, left atrial activation time, NT-proBNP, STROKESTOP2, paroxysmal atrial fibrillation, left atrial strain, ROC analysis, elderly screening, atrial remodeling, Cardiovascular Ultrasound