Objective To evaluate the feasibility and efficacy of intravascular optical coherence tomography (OCT) in the assessment of plaque characteristics and drug eluting stent deployment quality in the elderly patients with unstable angina (UA) and non-ST segment elevation myocardial infarction (NSTEMI). Methods OCT was used in elderly patients undergoing percutaneous coronary interventions. Fifteen patients, 9 males and 6 females with mean age of 72.6±5.3 years (range 67-92 years) were enrolled in the study. Images were obtained before initial balloon dilatation and following stent deployment. The plaque characteristics before dilation, vessel dissection, tissue prolapse, stent apposition and strut distribution after stent implantation were evaluated. Results Fifteen lesions were selected from 32 angiographic lesions as study lesions for OCT imaging after diagnostic coronary angiography. There were 7 lesions in the left anterior descending artery, 5 lesions in the right coronary artery and 3 lesions in the left circumflex coronary artery. Among them, 12 (80.0%) were lipid-rich plaques, and 10 (66.7%) were vulnerable plaques with fibrous cap thickness 54.2±7.3 μm. Seven ruptured culprit plaques (46.7%) were found; 4 in UA patients and 3 in NSTEMI patients. Tissue prolapse was observed in 11 lesions (73.3%). Irregular stent strut distribution was detected in 8 lesions (53.3%). Vessel dissections were found in 5 lesions (33.3%). Incomplete stent apposition was observed in 3 stents (20%) with mean spacing between the struts and the vessel wall 172±96 mm (range 117-436 mm). Conclusions 1) It is safe and feasible to perform intravascular OCT to differentiate vulnerable coronary plaque and monitor stent deployment in elderly patients with UA and USTEMI. 2) Coronary plaques in elderly patients with UA and USTEMI could be divided into acute ruptured plaque, vulnerable plaque, lipid-rich plaque, and stable plaque. 3) Minor or critical plaque rupture is one of the mechanisms of UA in elderly patients. 4) Present drug eluting stent implantation is complicated with multiple tissue prolapses which are associated with irregular strut distributions. 5) The action and significance of tissue prolapse on acute vessel flow and in-stent thrombus and restenosis need to be further studied. Objective To evaluate the feasibility and efficacy of intravascular optical coherence tomography (OCT) in the assessment of plaque characteristics and drug eluting stent deployment quality in the elderly patients with unstable angina (UA) and non-ST segment elevation myocardial infarction (NSTEMI). Methods OCT was used in elderly patients undergoing percutaneous coronary interventions. Fifteen patients, 9 males and 6 females with mean age of 72.6 ± 5.3 years (range 67-92 years) were enrolled in the study. Images were obtained before initial balloon dilatation and following stent deployment. The plaque characteristics before dilation, vessel dissection, tissue prolapse, stent apposition and strut distribution after stent implantation were evaluated. Fifty lesions were selected from 32 angiographic lesions as study lesions for OCT imaging after diagnostic coronary angiography. There were 7 lesions in the left anterior descending artery, 5 lesions in the right coronary artery Three lesions in the left circumflex coronary artery. Among them, 12 (80.0%) were lipid-rich plaques, and 10 (66.7%) were vulnerable plaques with fibrous cap thickness 54.2 ± 7.3 μm. Seven ruptured culprit plaques (46.7%) were Four of UA patients and 3 in NSTEMI patients. Tissue prolapse was observed in 11 lesions (73.3%). Incomplete stent apposition was observed in 3 stents (20%) with mean spacing between the struts and the vessel wall 172 ± 96 mm (range 117-436 mm). Conclusions 1) It is safe and feasible to perform intravascular OCT to differentiate vulnerable coronary plaque and monitor stent deployment in elderly patients with UA and USTEMI. 2) Coronary plaques in elderly patients with UA and USTEMI could be divided into acute ruptured plaque, vulnerable plaque, lipid-rich plaque, and stable plaque. 3) Minor or critical plaque rupture is one of the mechanisms of UAin elderly patients. 4) Present drug eluting stent implantation is complicated with multiple tissue prolapses which are associated with irregular strut distributions. 5) The action and significance of tissue prolapse on acute vessel flow and in-stent thrombus and restenosis need to be further studied studied .