Categorical variables were compared with the χ2 test or Fisher exact test as appropriate. A two-sided p-value of less than 0.05 was considered to represent a statistically significant difference. The correlation between LA stiffness and LA volume indices and mechanical

function indices were evaluated using Pearson’s correlation coefficient (PCC) and Spearman’s rank correlation coefficient (SCC). Results The baseline clinical and echocardiographic characteristics of 64 patients with paroxysmal AF and 36 normal control subjects Inhibitors,research,lifescience,medical are summarized in Table 1. There was no significant difference between the paroxysmal AF patients and normal control subjects, with respect to age, gender, heart rate, and body Duvelisib surface area (Table 1). Although LA A-P diameter was not significantly different between the two groups (3.7 ± 0.6 vs. 3.5 ± 0.5, p = 0.207), S-I diameter was increased Inhibitors,research,lifescience,medical in patients with paroxysmal AF, compared to the normal control subjects (5.2 ± 0.8 vs. 4.8 ± 0.5, p = 0.002). LA volumes were also significantly larger in the paroxysmal AF patients than in the normal control subjects (minimal

volume index, 16.6 ± 8.8 vs. 10.6 ± 4.6, p < 0.001; pre-A volume index, 22.3 ± 9.9 vs. 15.9 ± 6.5, p = 0.001; maximal volume index, 33.2 ± 11.4 vs. 26.7 ± 8.8, p = 0.004). Whereas, there Inhibitors,research,lifescience,medical was no significant differences in LV volume and mass indices, transmitral flow velocities and annular tissue velocities between the two groups (Table 1). Table 1 Clinical and echocardiographic Inhibitors,research,lifescience,medical characteristics in patients with paroxysmal atrial fibrillation and in normal control subjects Table 2 describes the LA mechanical function in patients with paroxysmal AF and in the normal control subjects. The reservoir function, as estimated Inhibitors,research,lifescience,medical by LA expansion index, was significantly decreased in patients with paroxysmal AF, compared to that of the normal control

subjects (118.1 ± 50.5 vs. 164.5 ± 54.4, p < 0.001). Whereas, decreased contractile function in patients with paroxysmal AF, as estimated by LA active emptying fraction, did not reach statistical significance (26.5 ± 12.8 vs. 31.7 ± 13.7, Thymidine kinase p = 0.056). There was no significant difference in LA energy, including kinetic energy (7.7 ± 7.6 vs. 6.6 ± 5.2, p = 0.449) and ejection force (1.1 ± 0.8 vs. 1.0 ± 0.7, p = 0.540) between the two groups. Paroxysmal AF patients showed lower global LA strain (27.3 ± 7.2 vs. 32.6 ± 7.0, p = 0.001) and higher LA stiffnessstrain (0.41 ± 0.24 vs. 0.29 ± 0.10, p = 0.001), compared to normal control subjects. However, when we estimate LA stiffness, using LA filling volume, LA stiffnessvol was not significantly different between two groups (0.68 ± 0.38 vs. 0.63 ± 0.26, p = 0.543). Table 2 Left atrial mechanical function in patients with paroxysmal atrial fibrillation and in normal control subjects Fig.