Left Ventricular Longitudinal Strain Detects Ischemic Dysfunction at Rest, Reflecting Significant Coronary Artery Disease

<b>Background/Objectives:</b> The role of speckle-tracking echocardiography in the diagnosis of stable coronary artery disease (CAD) remains controversial. The aim of this study was to assess the diagnostic accuracy of global longitudinal strain (GLS) in predicting significant CAD. <b>Methods:</b> In this prospective study, 103 symptomatic patients referred for invasive coronary angiography were enrolled. All patients underwent resting echocardiography with GLS assessment prior to angiography. Exclusion criteria included acute coronary syndrome, known history of CAD, and the presence of left ventricular wall motion abnormalities. Significant CAD was defined as ≥50% stenosis in at least one major epicardial coronary artery. <b>Results:</b> The mean patient age was 63.8 ± 9.3 years, with 78.6% being male. Hypertension was present in 63.1% of patients, dyslipidemia in 77.7%, diabetes mellitus in 22.3%, smoking history in 71.9%, and a family history of premature CAD in 24.3%. Significant CAD was identified in 45.6% (<i>n</i> = 47), while the remaining 54.3% (<i>n</i> = 56) had non-significant or no coronary artery disease. Patients with significant CAD exhibited significantly lower GLS values compared to those without (-15.73 ± 2.64% vs. -17.6 ± 1.85%, <i>p</i> = 0.001). A GLS threshold of >-16.3 predicted significant CAD with 66% sensitivity and 73.2% specificity (AUC = 0.692, <i>p</i> = 0.001). GLS demonstrated diagnostic accuracy in identifying disease in individual coronary territories, with AUCs of 0.754 for the left anterior descending artery (LAD), 0.714 for the left circumflex artery (LCx), and 0.723 for the right coronary artery (RCA). Diagnostic performance improved when GLS was combined across all three territories (AUC = 0.796). <b>Conclusions:</b> Resting myocardial GLS is accurate in detecting ischemic myocardial dysfunction and can accurately predict significant stenosis of the respective coronary branch subtending the segments.