Intravascular Ultrasound Evaluation Of Mild-to-Intermediate Coronary Lesions In Patients With Acute Myocardial Infarction And Unstable Angina Pectoris

Background: It has been widely accepted that patients with severe coronary artery stenosis are considered to be at higher risk and more able to be given further revascularization.While In clinical practice,some patients with acute myocardial infarction(AMI)and unstable angina pectoris(UAP)are observed with only mild-to-moderate stenosis angiographically.Coronary angiography(CAG)has known limitations in the assessment of lesion structure,so optimal management strategy can hardly be given in some cases,for which conservative medication is mostly used in treating with mild-to-moderate coronary lesions.However,by inserting catheter into the coronary artery,intravascular ultrasound(IVUS)as an emerging technique,is able to obtain important information about lumen size,plaque composition and lesion distribution of the culprit vessel,which can provide more accurate evaluation of lesion characteristics and guidance in treatment.Objective: This study aims to use IVUS to evaluate the lesion characteristics of the culprit vessel in patients who have AMI and UAP with mild-to-intermediate stenosis,and to explore the relationship between different lesion characteristics and different clinical presentation.So as to provide help for clinical identification of high-risk patients and improve their clinical prognosis.Methods: A total of 58 patients with mild-to-intermediate lesions who underwent both CAG and IVUS examinations were enrolled consecutively in the cardiovascular hospital of the first affiliated hospital of Dalian medical university during January 1,2017-August 31,2020.They were then divided into AMI group or UAP group according to the clinical presentation,results of electrocardiogram and hypersensitive troponin I.Meanwhile the baseline data,laboratory test results and images of the procedures of patients in the two groups were collected.Qualitative and quantitative analysis such as lumen size,plaque morphology and calcification characteristics were measured.SPSS 25.0 was applied for statistical analysis.Results:1.There were no significant differences in external elastic membrane diameter,lumen diameter,lumen eccentricity Index,EEM cross-sectional area,reference vessel CSA,lumen CSA,plaque plus media CSA,lumen CSA stenosis and plaque burden between AMI group and UAP group(p >0.05).2.In terms of plaque composition,fibrous plaques were the dominant lesions in AMI group,while fibrous plaques,calcified plaques and mixed plaques are usual to see in UAP group(p < 0.001).3.At minimum lumen area(MLA)site,the plaque CSA of AMI group was smaller than that of UAP group(6.9(4.1-8.6)vs.8.9(6.5-13.6),P =0.019),but there was no difference in plaque burden(p >0.05).4.In terms of vascular remodeling,negative remodeling was frequently observed in both groups,and is more common in AMI group than in UAP group(9(81.8%)vs.29(61.7%),p < 0.001).5.There were 2(18.2%)cases of plaque rupture and 1(9.1%)case of vulnerable plaque been observed in AMI group,which were significantly higher than that in UAP group(0cases(0.0%),p =0.003 and p =0.037).6.There was no difference in the proportion of patients with calcification between AMI group and UAP group(p >0.05).7.In terms of calcification location,calcification was distributed in both superficial and deep layers in both groups.However,the distribution of superficial calcification in UAP group was more than that in AMI group(31(66.0%)vs.3(27.3%),P =0.019),while there was no difference in the distribution of deep calcification and mixed calcification(p > 0.05).8.In terms of calcification pattern,both groups had the same spotty calcification detection rate,while more calcified nodules were found in AMI group(1(9.1%)vs.0(0.0%),p =0.037).9.In terms of calcification morphology,both groups presented mainly convex calcification(p >0.05).10.The calcification in UAP group was significantly longer than AMI group in terms of calcification length and arc(p =0.046),and the arc of calcification was also significantly larger(p =0.042).11.At the maximum calcification arc site,there is no difference between EEM diameter,lumen diameter,lumen eccentricity Index,EEM CSA,reference vessel CSA,lumen CSA,plaque plus media CSA,lumen CSA stenosis and plaque burden between two groups of patients.Although there are 7(14.9%)cases show colocalization of MLA and maximum calcification arc site in patients with UAP group,but the difference has no statistical significance(p > 0.05).Conclusion:1.Negative remodeling is frequently observed in both AMI group and UAP group,and is more common in patients with AMI.2.Compared with the UAP group,patients in the AMI group had the characteristics of unstable plaques,such as vulnerable plaque,plaque rupture and calcified nodules.3.Compared with the AMI group,patients in the UAP group had more calcified plaques,and the length of calcification were longer,the arc of calcification were larger.