Coronary Collateral Circulation in Coronary Syndromes: Echocardiographic Insights and Future Perspectives

Coronary collateral circulation (CCC) represents a natural adaptive mechanism capable of preserving myocardial perfusion in the presence of obstructive coronary artery disease. Although invasive angiography remains the reference method for collateral visualization, it provides limited information regarding collateral functionality and downstream myocardial protection. Echocardiography, due to its widespread availability, lack of radiation, and advances in imaging techniques, has emerged as an attractive non-invasive tool for evaluating the myocardial consequences of collateral perfusion. This review summarizes current evidence regarding the role of echocardiography in assessing coronary collateral circulation. Conventional echocardiographic parameters, stress echocardiography, myocardial contrast echocardiography, speckle-tracking imaging, myocardial work analysis and three-dimensional echocardiography are reviewed in the context of collateral-dependent myocardial function. Emerging technologies including artificial intelligence and quantitative perfusion imaging are also discussed. Rather than directly visualizing collateral vessels, echocardiography provides complementary information on the myocardial consequences of collateral-dependent perfusion through assessment of regional function, myocardial mechanics, and, with contrast techniques, tissue perfusion. However, collateral-specific validation remains limited, particularly for emerging deformation and myocardial work indices, and echocardiographic findings should be interpreted alongside coronary anatomy and physiological or perfusion measurements. Future integration with invasive assessment, multimodality imaging, and molecular markers may improve characterization of collateral-dependent myocardium.