Application Of Cardiac Magnetic Resonance Of Left Ventricular Structure And Function After Myocardial Infarction

Objective: Cardiac magnetic resonance(CMR)was used to analyze the left ventricle morphology,structural changes,and delayed myocardial intensified segments of old myocardial infarction(OMI).At the same time,cardiac magnetic resonance tissue tracking(CMR-TT)technique was used to analyze the overall left ventricular myocardial strain and evaluate The correlation between left ventricular ejection fraction(LVEF)and delayed enhancement(LGE)segments and the overall left ventricular myocardial strain.To investigate the predictive value of left ventricular myocardial strain on OMI and OMI without Major Adverse Cardiovascular Events(MACE).Methods: The patients who were diagnosed with myocardial infarction at Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital from January 2017 to August 2019,and who underwent CMR and enhanced scanning were the case group(48 people),and the group without myocardial infarction was the control group(50 people).The left ventricle was divided into 17 segments by the American Heart Association's left ventricular wall.The left ventricle was divided into 17 segments.Cardiac magnetic resonance imaging was used to evaluate the infarcted myocardial location and infarct range in patients with myocardial infarction.Then the Argus postprocessing software was used to analyze the left ventricular function parameters after myocardial infarction;and then measured the left ventricle's overall myocardial strain with CVI42 software,including: left ventricular global radial strain peak(LVGRSP),left ventricular global longitudinal strain peak(LVGLSP),and left ventricle overall circumferential strain peak LVGLSP)and so on.Comparisons between groups were performed using independent sample t test and Mann-Whitney U rank sum test.The correlation between left ventricular global myocardial strain and LGE and LVEF was analyzed by Pearson correlation.The left ventricular global myocardial strain was used to diagnose and predict the cut-off of OMI using ROC curve.And calculate the AUC,optimal critical value,sensitivity,and specificity of meaningful parameters.The consistency test uses the intra-class correlation coefficient(ICC).The test level(P)was 0.05,and P <0.05 was statistically significant.Results: Delayed enhancement segments appeared in the 48 cases,with a total of 816 segments,and the number of LGE segments was 272.The most LGE occurred in the side wall,and most of them were transmural enhancement.There was no significant difference in age,LVEF,LVEDV,LVESV,SV,CO,CI between the case group and the control parameters(p> 0.05).The LVGRSP,LVGLSP,and LVGCSP in the case group were significantly reduced,and the differences were statistically significant(p <0.05).Correlation analysis showed that the LVEF and LVGRSP in the case group were positively correlated(r = 0.711,p <0.001),and the LVGCSP and LVGLSP were negatively correlated(r =-0.857,p <0.001;r =-0.797,p <0.001);the number of LEG segments in the case group was negatively correlated with LVGRSP(r =-0.860,p <0.001),and positively correlated with LVGCSP and LVGLSP(r = 0.750,p <0.001;r =-0.616,p <0.001).The ROC curve indicates that the AUC of LVGRSP,LVGCSP,and LVGLSP in the case group are 0.071,0.986,and 0.915,respectively.The AUC of LVGCSP and LVGLSP are all greater than 0.9,and the AUC of LVGRSP is less than 0.5.The diagnostic accuracy of OMI is low and not obvious.Diagnostic value.The sensitivity of the calculated LVGCSP and LVGLSP are 90.8% and 83.3%,the specificity is 98.0% and 98.0% respectively,and the optimal critical values are-18.29% and-11.58%,respectively.The AUC values of LVGRSP,LVGCSP,and LVGLSP in OMI patients without major adverse cardiac events(MACE)were 0.071,0.986,and 0.915.The AUC values of LVGCSP and LVGLSP were all greater than 0.5,while the AUC values of LVGRSP were less than 0.5.Obvious diagnostic value.The sensitivity of the calculated LVGCSP and LVGLSP are 71.4% and 92.9%,the specificity is 58.8% and 32.4% respectively,and the optimal critical values are-8.74% and-9.84% respectively.Conclusion:(1)Most patients with OMI have transmural enhancement,and their LGE is mainly located in the side wall.(2)The cardiac magnetic resonance tissue tracking technology can analyze and evaluate the overall left ventricular myocardial strain in OMI patients.(3)Longitudinal,radial,and circumferential strains of left ventricular myocardium have a strong correlation with the number of EF and LGE segments in the left ventricle of OMI,thus becoming a new parameter for evaluating OMI cardiac function.(4)LVGCSP and LVGLSP have certain predictive diagnostic value for OMI and OMI without without Major Adverse Cardiovascular Events,and can provide accurate and comprehensive clinical reference information for patients' short-term diagnosis and long-term prognostic risk assessment.