The Value Of MRI Myocardial Strain Analysis In Assessing Cardiac Function In Obese Patients With Ejection Fraction Retention

Purpose:In this study,we leveraged cardiovascular magnetic resonance(CMR)to assess the changes of cardiac morphology and function in obese patients with retained ejection fraction,and used feature tracking technology to compare the left cardiac strain between the normal and obese patients.Moreover,we further analyzed the correlation between myocardial strain and clinical laboratory indicators and fat distribution to investigate the early cardiac function changes in obese patients and provide a reliable evaluation tool for timely intervention.Materials and methods:A total of 45 obese patients(age,15-60 years;body mass index[BMI],28-48 kg/m~2)who met the inclusion and exclusion criteria were enrolled from Jinan University Bariatric and Metabolic Surgery Center between January 2021and January 2022,as well as 40 healthy volunteers(age,15-60 years;BMI<28 kg/m~2)were recruited as normal control group.All subjects had underwent 3.0T CMR and upper abdominal iterative decomposition of water and fat with echo asymmetry and least-squares estimation-iron sequence(IDEAL-IQ)scans.The primary sequences of CMR included the short-axis and long-axis four-chamber and two-chamber FIESTA sequence.Subsequently,the CMR images were post-processed using the commercial cardiac multi-function post-processing software CVI42,and the end-diastolic strain peaks of the left atrium and left ventricle were measured based on cine images,and the area and mass of epicardial adipose tissue(EAT)were measured on short-axis cine images.The ectopic fat contents were measured manually on a GE postprocessing workstation.Clinical information included height,weight,neck circumference,chest circumference,waist circumference and hip circumference,laboratory tests consisted of triglyceride,low-density lipoprotein and high-density lipoprotein.All data of the obese and normal control groups were compared between groups,left atrial strain was correlated with other indicators,and the factors related to myocardial strain were analyzed by stepwise multiple linear regression analysis.Results:Finally,30 obese patients(30.4±8.5 years)and 30 normal control volunteers(28.2±7.5 years)were enrolled.All subjects had normal left ventricular ejection fraction,and there was no significant difference between the two groups(P=0.38).For the morphological features of the left ventricle,the left ventricular mass(LVM)of the obese group was significantly higher than the normal control group(98.43±46.05g vs.70.30±15.74 g,P=0.002).Regarding the cardiac function parameters of the left ventricle,the left ventricular cardiac output(CO)of the obese group was significantly higher than that of the normal group(6.63±1.68 L/min vs.5.27±0.96 L/min,P<0.001).Comparing the myocardial straining between the two groups,the overall peak radial strain(PRS)of the left atrium at the end-diastole of the obese group was significantly lower than that of the control group(-12.87±3.43%vs.-15.36±2.68%,P=0.007).The overall peak longitudinal strain(PLS)of the left atrium in the obese group was significantly lower than that of the control group(23.00±7.61%vs.30.14±8.30%,P=0.002).Additionally,the peak left atrial longitudinal strain was negatively correlated with triglyceride(β=-0.30,P=0.035)and left ventricular mass(β=-0.529,P=0.001).The peak left atrial radial strain was positively correlated with epicardial fat(β=0.50,P=0.001),neck circumference(β=0.50,P=0.001)and high-density lipoprotein(β=0.40,P=0.001).Conclusions:The quantitative analysis of left ventricular myocardial strain by CMR feature tracking technology showed that the decrease of left atrial strain in obese patients occurred prior to the abnormalities of left ventricular ejection fraction,indicating that there was subclinical cardiac involvement in obese patients.Left atrial strain was associated with triglycerides,left ventricular mass,neck circumference,high density lipoprotein,and epicardial fat.Thus,the strain index of the left atrium can detect the impaired cardiac diastolic function of obese patients earlier and more sensitive,which provides important guidance for early diagnosis,early treatment and improvement of patient prognosis.