[Clinical applications of strain rate imaging for evaluation of left atrial function]

Left atrial (LA) function plays an important role in patients with left ventricular dysfunction and atrial fibrillation, and has been assessed using several noninvasive methods. However, there are a number of limitations regarding clinical application, including the dependence of altered left ventricular hemodynamics, image quality, single plane assessment, and the tethering effect. Strain rate (SR) imaging is a novel echocardiographic technique for assessing LA function, which enables the quantification of LA function in patients with atrial fibrillation, hypertension, diabetes mellitus, obesity, atrial septal defect, dilated cardiomyopathy, and cardiac amyloidosis. Furthermore, SR imaging can identify LA dysfunction in patients with hypertension or diabetes mellitus, even in the absence of LA dilation or functional LA impairment assessed by conventional Doppler echocardiography and tissue Doppler imaging. LA deformation assessed by SR imaging is a predictor of the maintenance of a sinus rhythm after either electrical cardioversion or catheter ablation for atrial fibrillation. Recently, two-dimensional speckle tracking echocardiography has been used as a noninvasive, simple, and reproducible technique for assessing LA function in patients with either physiological or pathological left ventricular hypertrophy. LA dysfunction detected by either SR imaging or two-dimensional speckle tracking echocardiography may be associated with the development of heart failure, thromboembolism, and atrial fibrillation, and should undergo further investigations. In this review, the clinical applications of SR imaging for LA function evaluation are summarized.