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

Abstract Purpose To study left atrial stiffness index (LASI) and left atrial activation time (LA-AT) changes in an older population with silent paroxysmal atrial fibrillation (PAF) compared to age-matched control. Methods Individuals with newly diagnosed PAF and a randomly selected age-matched control group without AF were enrolled from STROKESTOP2-study. All participants had NT-proBNP levels 125–900 ng/L. TTE examinations were analyzed retrospectively offline using dedicated software. Besides conventional echocardiographic measurements, LA-AT was obtained by measuring the time delay between the onset of the P-wave on ECG and tissue Doppler Á peak wave in lateral LA wall. LASI was calculated as the ratio of left ventricular filling (E/é) to peak atrial longitudinal strain (PALS). Results Mean age was 76 ± 0.3 years. The PAF group ( n = 67) presented significant increase of LASI (0.41 (0.29–0.60) vs. 0.32 (0.29–0.43), P = 0.001) and prolonged LA-AT (170 (140–180) ms vs. 140 (120–144) ms, P < 0.001) compared to controls ( n = 94). Subgroup analysis in participants with normal LA volume index (LAVI) ≤ 34 ml/m 2 , LASI and LA-AT remained significantly increased/prolonged in PAF ( N = 27) compared to controls ( N = 72). NT-proBNP-levels did not differ between PAF (228 (181–348) ng/L) and controls (216 (156–317) ng/L) ( P = 0.18). ROC curve analysis identified thresholds LASI > 0.54 and LA-AT > 139 msec for discrimination of silent PAF. Conclusion Indices reflecting LA stiffness and atrial conduction delay were significantly elevated in recently diagnosed PAF patients. LASI and LA-AT thresholds might non-invasively detect early atrial remodeling without structural enlargement in elderly patients with high risk of PAF and mildly increased NT-proBNP levels.