Clinical and prognostic impact of left atrial strain in non-ischemic cardiomyopathies

Over the last decade, left atrial (LA) strain has gained attention as a clinical diagnostic and prognostic non-invasive imaging parameter. LA strain measures the myocardial deformation of the LA in three phases; the reservoir (LA filling during ventricular systole), the conduit (passive filling of the left ventricle [LV]) and the booster phase (late-diastolic active atrial contraction). LA strain reflects both diastolic and systolic myocardial function and is presumed to be an early marker of atrial and ventricular dysfunction. The aim of this review article is to discuss the (patho)physiology of LA strain, different LA imaging modalities, and to provide a contemporary update on the current evidence of clinical diagnostic and incremental prognostic implications of LA strain, with respect to conventional imaging parameters such as left ventricular ejection fraction, LA volume and late gadolinium enhancement. We will focus on non-ischemic cardiomyopathies, as these often present with a complex interplay of structural and functional myocardial abnormalities, including atrial myopathy. This includes dilated and hypertrophic cardiomyopathy, amyloidosis and myocarditis, highlighting current limitations and future perspectives of its clinical implications.