| Part 1: Correlation between left ventricular structure and function and hepatic fat fractionObjective: To investigate the correlation between left ventricular structure and function based on echocardiographic assessment and hepatic fat fraction measured by MR m Dixon in patients with non-alcoholic fatty liver disease（NAFLD）.Methods: Those who had both abdominal MR m Dixon technique and echocardiography within one week from January 2020-October 2022 were included.Patients who met the diagnosis of NAFLD were included according to the 2016 practice guidelines for clinical management of NAFLD and the 2018 guidelines for prevention and treatment.Patients with NAFLD were also classified into three groups of mild,moderate and severe according to hepatic fat fraction（HFF）measured by MR m Dixon.The differences in variability of clinical baseline data and left ventricular structural and functional parameters between the three groups were assessed by chi-square test,Kruskal-Wallis rank sum test and analysis of variance,and the correlation between left ventricular structure and function and HFF in patients with NAFLD were assessed by spearman.Patients with NAFLD were further divided into a group with left ventricular diastolic insufficiency（E/A <1）and a group with normal left ventricular diastolic function（E/A ≥1）based on the ratio of peak mitral flow velocity in early left ventricular diastole（E peak）to peak mitral atrial systolic flow velocity（A peak）（E/A）.The differences between the two groups were analyzed using the chi-square test,Wilcoxon rank sum test and independent samples t-test.Logistic regression was used to analyze the influential risk factors for left ventricular diastolic insufficiency in patients with NAFLD.The receiver operating characteristic（ROC）curves were used to assess the predictive effect of risk factors for left ventricular diastolic insufficiency in patients with NAFLD.The differences in the predictive effectiveness of the models were assessed using the Delong test.P < 0.05 was considered a statistical difference.Results: 118 patients with NAFLD were finally enrolled,including 45 patients in the mild group,42 patients in the moderate group and 31 patients in the severe group.1)Comparison of the clinical baseline data of the three groups showed that the differences in alanine aminotransferase（ALT）,aspartate aminotransferase（AST）and triglyceride（TG）were statistically significant（P< 0.05）.Comparison of left ventricular structural and functional parameters assessed by echocardiography in the three groups showed that: Comparison of left ventricular structural and functional parameters assessed by echocardiography in the three groups showed that: E/A was statistically significant（P<0.05）in the three groups and was significantly lower in the moderate and severe NAFLD groups compared to the mild NAFLD group（P<0.05）;E/A was significantly lower in patients with severe NAFLD compared to the moderate NAFLD group（P=0.027）.The differences in left ventricular end diastolic diameter（LVEDD）,interventricular septum thickness（IVST）,left ventricular posterior wall thickness（LVPWT）,left ventricular mass（LVM）,left ventricular mass index（LVMI）and left ventricular ejection fraction（LVEF）were not statistically significant between the three groups.3)Spearman’s correlation analysis showed a negative correlation between HFF and E/A（rs=-0.418,P<0.001）and no correlation with LVEDD,IVST,LVPWT,LVM,LVMI and LVEF（P>0.05）.Patients with NAFLD were grouped according to the presence or absence of left ventricular diastolic insufficiency showed that there were 85 patients in the left ventricular diastolic insufficiency group and 33 patients in the normal left ventricular diastolic function group.Multivariate binary logistic regression analysis showed that age and HFF were effective predictors of left ventricular diastolic insufficiency（P< 0.05）and that the risk of developing left ventricular diastolic insufficiency increased with age（ratio（OR）=1.068,95% CI: 1.022 to 1.116,P=0.004）and HFF（OR=1.140,95% CI:1.060 to 1.226,P<0.001）increased.The ROC curve analysis showed that the area under the curve（AUC）was in descending order for the combined model of age and HFF（0.828,95% CI: 0.748 to 0.891,P<0.0001）,HFF（0.755,95% CI: 0.668 to 0.830,P=0.0001）,and age（0.719,95% CI: 0.629 to 0.798,P=0.0001）.Further,Delong’s test showed significant difference between the combined model of age and HFF and the single model of age（P=0.007）.The cut-off value of HFF was 11.72%,with a sensitivity of 70.59% and a specificity of 78.79%.The cut-off value of age was 47,with a sensitivity of 82.35% and a specificity of 57.58%.Conclusions: HFF was negatively correlated with E/A value.This suggests that as the severity of NAFLD increases,left ventricular diastolic function was more likely to be impaired.In addition,age and HFF were effective predictors of left ventricular diastolic insufficiency in patients with NAFLD.Part 2: Correlation between left ventricular myocardial strain and hepatic fat fractionObjectives: To explore whether subclinical left ventricular myocardial strain was altered in patients with NAFLD using cardiac magnetic resonance-feature tracking（CMR-FT）technology and to analyze the correlation between HFF and left ventricular myocardial strain in patients with NAFLD.Methods: Those who underwent CMR examination and abdominal MR m Dixon technique within one week were included.All participants had normal LVEF（LVEF≥50%）and no clinical symptoms of cardiac insufficiency,and were divided into NAFLD group（HFF > 5%）and control group（HFF ≤ 5%）according to hepatic fat fraction（HFF）measured by MR m Dixon.Short-axis cine sequences were imported into the SAX Function module of the cvi42 software to obtain left ventricular ejection fraction（LVEF）,left ventricular end-diastolic volume（LVEDV）and left ventricular end-systolic volume（LVESV）;Short-axis,2-chamber,3-chamber and 4-chamber cine sequences were opened in the Tissue Tracking module to obtain global strain and strain rates in three directions,including global longitudinal strain（GLS）,global circumferential strain（GCS）,global radial strain（GRS）,global diastolic peak longitudinal strain rate（GLPDSR）,global diastolic peak circumferential strain rate（GCPDSR）,global diastolic peak radial strain rate（GRPDSR）,global longitudinal peak systolic strain rate（GLPSSR）,global circumferential peak systolic strain rate（GCPSSR）,global radial peak systolic strain rate（GRPSSR）.The differences between the two groups were assessed by chi-square test,Wilcoxon rank sum test and independent samples t-test.P < 0.05 was considered a statistical difference.Results: There were 42 cases in the NAFLD group and 31 cases in the control group.The GLS,GCS,GLPDSR,and GCPDSR in the NAFLD group were smaller than in the control group(-14.92±3.37 vs-17.54±2.59%;-19.41±3.23 vs-20.77±2.00%;0.81（0.65,0.96）vs 0.97（0.79,1.44）s-1;1.01（0.74,1.22）vs 1.23（1.08,1.48）s-1)and the differences were statistically significant（P< 0.05）.However,the differences in GRS,GRPDSR,GLPSSR,GCPSSR and GRPSSR were not statistically significant between the two groups（P> 0.05）.Spearman correlation analysis showed that the HFF of patients with NAFLD was moderately negatively correlated with GLPDSR（rs=-0.503,P=0.001）and GCPDSR（rs=-0.436,P= 0.004）.At the same time,there was no correlation with GLS,GCS,GRS,GRPDSR,GLPSSR,GCPSSR,GRPSSR（P>0.05）.Conclusions: CMR-FT can detect abnormal LV myocardial strain in NAFLD patients with normal LVEF and the LV strain parameters（GLPSSR,GCPSSR）decreased with the increasing of HFF in NAFLD patients. |
