In chronic mitral regurgitation (MR) left atrium is one of the first cardiac structures that is involved in remodeling and ultrastructural changes for a progressive volume overload. Severe left atrial (LA) dilation on echocardiography and new onset of atrial fibrillation in asymptomatic patients with preserved Left Ventricular (LV) function, appeared as a Class IIb recommendation for consideration for surgical mitral valve repair in the actual guidelines. However, before atrial dilatation and dysfunction, several ultrastructural changes appear in the atrial muscle tissue that are difficult to identify with the standard echocardiography. Speckle tracking echocardiography (STE) can analyze LA function: it has been showed that it can indirectly identify structural tissue modifications from excessive atrial effort in the early stages of MR up to the full depression of atrial function in the late stages where there are advanced ultrastructural alterations. This review aims to summarize current knowledge on the role of atrial strain identifying early structural alterations of the atrial tissue in the rising stages of MR considering that Left Atrial Peak Longitudinal Strain (PALS) considered useful parameter for a more extensive evaluation of MR patients.