To determine the left atrial longitudinal strain discrimination threshold of atrial fibrillation (AF) in patients with dilated cardiomyopathy (DCM). A total of 100 DCM patients and LVEF < 25% were included. Of them, 50 had sinus rhythm (SR), and 50 had AF. Patients with significant valvular disease, cardiac pacemakers and prosthetic valves were excluded. Speckle tracking echocardiography was performed to visualize the inferior and lateral walls of the left atrium as well as the interatrial septum. The Q-Analysis software was used to assess left atrial contractile strain (εCT) during the atrial systole and left atrial conduit strain (εCD) during the atrial filling. In SR patients analysis was P-wave timed. In AF patients the reference point was at 200 ms before the QRS complex on the surface ECG. The εCD was significantly higher in SR patients than in those with AF (9.68% vs. 4.7%; p = 0.0003). ROC analysis demonstrated that εCD less than 5.43% (AUC 0.95; 95% CI 0.905-0.995; p < 0.0001) together with εCT below - 1.97% (AUC = 0.97; 95% CI 0.46-1.00; p < 0.0001) identified patients with AF. In patients with LVEF < 25% and AF left atrial contractile strain analysis is feasible. In these patients both contractile and conduit strain values are significantly lower than in patients with preserved SR, and εCD below 5.43% and εCT less than - 1.97% distinguish SR from AF patients with LVEF < 25%.
Keywords: Atrial fibrillation; Dilated cardiomyopathy; Left atrial strain; Sinus rhythm.