Left atrial strain in left ventricular diastolic dysfunction: have we finally found the missing piece of the puzzle? Giulia Elena Mandoli 1 & Nicolò Sisti 1 & Sergio Mondillo 1 & Matteo Cameli 1 # Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract The noninvasive estimation of diastolic function with echocardiography as a surrogate of left ventricular filling pressure is considered an essential step in the clinical evaluation of patients with conditions predisposing to heart failure (HF). Latest algorithms for the assessment of diastolic dysfunction (DD) lay on several 2D standard parameters and describe a precise grading to quantify its severity. The persistence of a “gray zone” of values in which DD quantification is not possible, together with an epidemiological increase of conditions predisposing to heart failure with preserved ejection fraction (HFpEF), has led to the search and use of parameters with higher specificity and sensitivity: one of these is left atrial (LA) longitudinal strain in the frame of speckle tracking echocardiography (STE). LA anatomy and mechanics are crucial for preserving left ventricular (LV) function and asymptomatic condition of the patient. LA longitudinal strain is angle-independent, thus overcoming Doppler limitations, and provides reproducible measures of LA deformation. This review examines the latest evidences concerning the use of LA longitudinal strain in the assessment of diastolic function and HFpEF, with a particular focus on its role in standard echocardio- graphic algorithms or as a lone parameter to guide diagnosis and therapeutic management. Keywords Diastolic function . Left atrium . Speckle tracking echocardiography . Left atrial strain . HFpEF Background The assessment of left ventricular diastolic function is consid- ered an integral part of the clinical evaluation of patients pre- senting with symptoms of heart failure. HFpEF accounts for the 35–50% of all HF cases, and abnormal filling pressure despite normal systolic function is the discriminative parame- ter from HF with reduced ejection fraction (HFrEF). Echocardiography represents the preferred alternative for a noninvasive estimation of LV filling pressure, a direct index of diastolic function, and its use has been recently updated in the 2016 ESC guidelines where different algorithms for pre- served and reduced EF are proposed[1][2]. The left atrium plays an active role in modulating LV filling, and its evalua- tion has raised increasing interest for both structural and func- tional parameters. In particular, alteration in atrial functional parameters becomes evident at the earliest stage of LV diastol- ic dysfunction (LVDD), and their echocardiographic analysis can be useful for both diagnosis and grading of this condition, also when morphologic parameters are still normal [3, 4]. Although standard 2D echocardiography is the recommended tool in guidelines, speckle tracking echocardiography is the most specific and sensitive method for the functional assess- ment of LA through atrial strain assessment. The aim of this review is to summarize the main evidences about the role of LA strain parameters in determining the diastolic function of LV, highlighting the possibility of its use as a pivotal param- eter for quantification of LV filling pressure (LVFP) especially when standard criteria are not enough sensitive for its classification. Focus on echocardiographic assessment of left ventricular diastolic dysfunction Standard echocardiography is still considered the first-line tool for diastolic function description. According to a recent multicenter study which compared invasively measured LVFP to its echocardiographic estimation, the accuracy of noninva- sive measurement is 87% with an addictive improvement of 1.5 times to single clinical assessment [5]. Similarly, the EACVI Euro-Filling study revealed that the 2016 ESC * Nicolò Sisti nic.sisti@gmail.com 1 Department of Cardiovascular Diseases, University of Siena, Siena, Italy Heart Failure Reviews https://doi.org/10.1007/s10741-019-09889-9