Evaluation Of Location And Size Of Myocardial Infarction On Left Atrial Function Based On Cardiovascular Magnetic Resonance Feature Tracking

Objective: To investigate the effect of location and size of previous myocardial infarction(MI)on left atrium(LA)function using CMR-FT.Methods: The patients who were diagnosed with myocardial infarction in the First Affiliated Hospital of China Medical University from April 2017 to June 2021 were retrospectively analyzed(n=82),including 42 patients with anterior myocardial infarction,40 patients with non-anterior myocardial infarction and 47 healthy controls.Six months after myocardial infarction,the patient underwent 3.0 T MR plain scan,dynamic contrast-enhanced MRI scan and late gadolinium enhancement(LGE)scan and were collected clinical indicators such as the patient’s age,gender,height,weight,body mass index,body surface area,NTpro-BNP.Two radiologists sketched out the ROI of endocardium and epicardium on Cvi42 workstation.The left atrial morphological parameters and functional parameters including left atrial reservoir,conduit and pump function were analyzed in two-chamber and four-chamber cardiac film images by using cardiac magnetic resonance feature tracking.The clinical parameters and atrial morphological and functional parameters of patients in different groups were analyzed by SPSS and the above parameters were compared with each other by means of Pearson correlation analysis.Results: This study finally included 82 patients with myocardial infarction(42 cases in anterior group and 40 cases in non-anterior group).Among the parameters of left atrial function,compared with the contrast group(P < 0.05),the left atrial reserve function(left atrial total ejection fraction,left atrial total strain,left atrial total strain rate)(LATEF,εs,SRs)and catheter function(left atrial passive ejection fraction,left atrial passive strain,left atrial passive strain rate)(LAAEF,εe,SRe)of patients with anterior wall myocardial infarction.Left atrial strain is damaged in patients with non-anterior myocardial infarction(total left atrial strain,passive left atrial strain,active left atrial strain;p<0.05)(εs,εe,εa;p< 0.05),but left atrial ejection fraction(LAEF)was preserved(p > 0.05).After adjusting the myocardial infarction area,there was no significant difference in left atrial morphology and function between the anterior wall group and the non-anterior wall group.According to the size of myocardial infarction,the left atrial volume and LAEF of patients with myocardial infarction size ≤ 15% did not change(P > 0.05).Only left atrial total strain and left atrial passive strain decreased(P < 0.05).Compared with the group with myocardial infarction size ≤ 15%,patients with myocardial infarction size> 15%had lower left atrial volume index before contraction(LAVIpre-a),left atrial minimum volume index(LAVI min),LATEF and increased LAAEF(P < 0.05).Correlation analysis showed that myocardial infarction area was weakly related to LAVI pre-a(ml/m2)(r = 0.25,p = 0.023),LAVI min(ml/m2)(r = 0.265,p = 0.016)and LATEF(%)(r=-0.349,p=0.001),LAPEF(%)(r=-0.325,p=0.003)and LAAEF(%)(r=-0.25,p=0.021).Conclusions:Left atrial function including reservoir,conduit and booster function are impaired after myocardial infarction.Location of myocardial infarction can affect left atrial function.The size can also be a main factor affecting LA remodeling and dysfunction.Patients with MI size>15% experience more pronounced post-infarction LA remodeling and dysfunction than MI size≤15% patients.