OBJECTIVES: This study aimed to investigate the vascular response of lesions with a layered phenotype. BACKGROUND: Recent studies have shown that layered plaques at culprit lesions detected by optical coherence tomography (OCT) have greater plaque burden and more inflammatory features than non-layered plaques. METHODS: This is a retrospective observational study. A total of 193 target lesions from 193 patients [100 patients with acute coronary syndromes (ACS) and 93 with stable angina pectoris (SAP)] who had undergone OCT imaging of the culprit lesion both before and after stenting were included. Layered plaques were identified by OCT as plaques with layers of different optical density. Patients were divided into two groups based on the presence or absence of a layered phenotype at the culprit lesion, and pre- and post-procedure OCT findings were compared. RESULTS: Among 193 patients, 36 (36.0%) lesions in ACS patients and 56 (60.2%) lesions in SAP patients were found to have a layered phenotype at the culprit lesion. At baseline, percent area stenosis was greater in layered plaque than in non-layered plaque (p = .019). Following stent implantation, the stent expansion ratio and mean stent eccentricity index were significantly lower in layered plaques than in non-layered plaques (p = .041, p = .017, respectively), mainly derived from ACS patients. CONCLUSION: Following stent implantation, plaques with a layered phenotype had less stent expansion and more eccentric lumens. Aggressive balloon dilation may be required to obtain optimal stent outcomes in patients with a layered plaque phenotype at the culprit lesion.