When the Liver Echoes to the Heart: Assessing Subclinical Cardiac Dysfunction in NAFLD Using Speckle Tracking Echocardiography—A Systematic Review and Meta-Analysis

<b>Introduction:</b> Worldwide, non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disorder, strongly associated with increased cardiovascular morbidity and mortality. Although patients have a preserved left ventricular ejection fraction (LVEF), individuals having NAFLD may demonstrate subclinical cardiac dysfunction. Speckle tracking echocardiography (STE) enables a more sensitive evaluation, identifying even subtle alterations of myocardial strain, compared to conventional LVEF measurements. This systematic review and meta-analysis sought to examine the relationship between NAFLD and subclinical left ventricular systolic impairment, utilizing STE-derived strain parameters. <b>Methods:</b> A comprehensive search of the literature was undertaken using PubMed, EMBASE, and Scopus. Observational studies evaluating patients with NAFLD through STE-derived myocardial strain parameters were included. Study quality was appraised using the Newcastle-Ottawa Scale. The primary outcomes were the mean differences (MD) in global longitudinal strain (GLS), global circumferential strain (GCS), global radial strain (GRS), global area strain (GAS), and related strain rate indices between NAFLD spectrum patients and controls. <b>Results:</b> A total of sixteen studies, comprising 8359 participants, were included in the analysis. Compared to controls, patients with NAFLD demonstrated significant reductions in GLS (MD: -2.043; 95% CI: -2.868, -1.218), GAS (MD: -3.706; 95% CI: -4.999, -2.413), and GCS (MD: -1.415; 95% CI: -2.893, 0.064). These reductions were more substantial among individuals with moderate to severe NAFLD and those with concomitant type 2 diabetes mellitus (GLS MD: -4.385; 95% CI: -5.400, -3.369 in diabetic NAFLD vs. diabetic controls). Subgroup analysis further revealed a progressive deterioration in strain parameters from simple steatosis to more severe NAFLD. Notably, LVEF remained preserved in all groups, highlighting the subclinical nature of this dysfunction. <b>Conclusions:</b> This meta-analysis verifies the presence of subclinical left ventricular systolic dysfunction in individuals with NAFLD, which is identifiable by STE despite preserved LVEF. Myocardial strain metrics, particularly GLS, serve as sensitive early markers of myocardial impairment. Routine application of STE in the clinical assessment of NAFLD may support earlier cardiovascular risk detection and timely intervention.