Insulin-like growth factor 1 (IGF-1) is the primary peripheral mediator of growth hormone (GH) and has pleiotropic effects on development, differentiation, metabolism, and cell survival. Several in vivo and in vitro studies suggest that IGF-1 may have a protective effect on atherosclerosis as it suppresses macrophage recruitment and activation, cytokine production, and extracellular matrix degradation while promoting smooth muscle cell migration and proliferation and extracellular matrix deposition. The protein sKlotho appears to be closely related to the GH-IGF-1 axis, and some animal and in vitro studies hypothesize its protective role in the cardiovascular system. The GH-IGF-1 axis and sKlotho influence mechanisms determining coronary atherosclerosis. Circulating levels of IGF-1 and sKlotho may correlate with the morphology of atherosclerotic plaques and particularly with the vulnerability of coronary lesions. Objectives: To evaluate the correlation between atherosclerotic plaque phenotype and the GH-IGF-1 axis and sKlotho in patients with chronic coronary syndrome using intravascular imaging with Optical Coherence Tomography (OCT). Methods:All patients with chronic coronary syndrome who meet the inclusion and exclusion criteria and undergo coronary angiography and intravascular imaging with optical coherence tomography will be included. At the end of the procedure, a blood sample will be taken to measure IGF-1, sKlotho, and GH receptor (GHR) polymorphism.