Assessment of Vascular Remodeling in Coronary Artery Aneurysm and Ectasia Using Optical Coherence Tomography: A Comparative Analysis of Dilated and Non-Dilated Segments

<b>Background:</b> Coronary artery aneurysm and ectasia (CAAE) represent uncommon forms of coronary artery disease characterized by abnormal arterial dilatation and complex remodeling. The mechanisms underlying their development remain poorly defined. Optical coherence tomography (OCT) provides high-resolution evaluation of plaque morphology and vessel wall structure, offering insights into the pathophysiology of CAAE. <b>Methods:</b> We analyzed 21 patients with angiographically confirmed CAAE who underwent intracoronary OCT. Dilated segments were compared with adjacent non-dilated reference segments. Quantitative measurements included the maximal dilated segment's diameter, reference diameter, and intima-media thickness. Qualitative assessment focused on plaque composition, calcification, neovascularization, fibrous cap characteristics, and thrombus. <b>Results:</b> Aneurysmal segments displayed larger lumen dimensions but no proportional increase in plaque burden, consistent with exaggerated positive remodeling. Compared with non-aneurysmal regions, CAAE segments exhibited significantly smaller calcification arcs and a lower prevalence of lipid plaques and neovascularization, suggesting a heterogeneous and potentially more fibrotic remodeling pattern. Classical features of plaque vulnerability were not consistently present in dilated segments, suggesting that hemodynamic factors, such as disturbed flow and stenosis, may contribute substantially to the thrombotic risk. <b>Conclusions:</b> OCT reveals distinct structural and compositional characteristics in CAAE, supporting the concept of maladaptive remodeling rather than uniformly unstable plaque. High-resolution intracoronary imaging enhances understanding of CAAE pathophysiology and may facilitate individualized clinical assessment and management.