Left atrial function assessment to refine indications to mitral valve surgery

The left atrial (LA) strain evaluation by means of spackle tracking echocardiography (STE) has been increasingly investigated in recent years to assess LA dysfunction in atrial fibrillation (AF). LA strain follows atrial deformation through the cardiac cycle, reflecting the LA reservoir, conduction, and contractile phases [1]. Moreover, LA strain proved to be associated with AF occurrence and to be progressively more impaired in patients with mitral regurgitation (MR) and repeated episodes of paroxysmal AF and was also associated with the development of postoperative AF in patients undergoing mitral valve surgery [2]. During the early phases of MR, the LA compensates for the increase in regurgitant volume by augmenting its reservoir function. However, in more advanced phases, the LA is no longer able to compensate and LA adverse remodelling occurs manifesting as dilatation and dysfunction. These changes may be followed by cellular hypertrophy and interstitial fibrosis, with increased vulnerability to the development of AF [3]. Therefore, decreased LA reservoir function may represent the first sign of the haemodynamic presence of severe MR at an earlier stage, occurring before overt LA structural changes. In this context, LA strain may represent a useful tool to improve the clinical decision-making process related to the optimal timing of intervention in patients with MR. Furthermore, STE could be useful to identify patients prone to develop AF to optimize the risk stratification of patients with MR. Noteworthily, there is today a growing interest in the possible use of prophylactic concomitant ablation and/or left atrial appendage obliteration (LAAO) in patients undergoing valve surgery before any evidence of AF [4, 5]. Particularly, LAAO has raised renewed interest after the clear-cut results of the LAAOS III trial, showing a strong stroke preventing power in cardiac surgery candidates with AF history [6]. Nevertheless, there is concern on a potential pro-AF effect of prophylactic LAAO during open heart surgery [7], and, most importantly, the haemodynamic drawbacks of LAAO are not clearly understood, particularly in patients with a restrictive left ventricular filling. Therefore, better insight on the prognostic significance of LA strain is today particularly welcome also in this context. Unfortunately, STE LA function evaluation lacks a universal method of execution and disease-specific cut-off reference values. This prompted several attempts of standardization [8, 9].