| Purpose:Type 2 diabetes mellitus(T2DM)is a kind of metabolic disease characterized by the continuous high blood glucose level due to insulin resistance.Its prevalence rate rises continually,which has caused serious social health burden.Long term hyperglycaemia may lead to interstitial fibrosis and myocardial microcirculation disorders and other manifestations of diabetic cardiomyopathy.However,when left ventricular remodelling occurs in diabetes mellitus,it is easy to be secondary to mitral regurgitation,leading to increased left ventricular preload,pressure of left atrial and pulmonary venous and resulting in right ventricular dysfunction,thus aggravating myocardial injury.Previous MRI studies of diabetic heart disease rarely pay attention to the abnormal mitral valve function.However,all-cause mortality increased 3.3-fold in diabetic patients with mild mitral regurgitation and 5.1-fold in patients with moderate to severe mitral regurgitation compared with diabetic patients without valve abnormalities.Therefore,it is of great significance to evaluate the changes of cardiac structure,function and strain in patients with type 2 diabetes mellitus complicated with mitral regurgitation for reducing cardiovascular risk and improving prognosis.Cardiac magnetic resonance(CMR)tissue tracking technology can overcome the limitations of traditional left ventricular ejection fraction(LVEF)and better describe the global and local changes of myocardial function.CMR tissue tracking technology has been widely used to evaluate the myocardial biomechanical characteristics of various cardiomyopathy by labeling and tracking each voxel of CMR cine sequence.However,there are few studies in T2DM patients with isolated mitral regurgitation.Therefore,this study retrospectively included diabetic patients with clinical diagnosis,combined with CMR scanning,obtained a number of cardiac structure,function and strain parameters through image post-processing technology,in order to quantitatively evaluate the changes of left ventricular,left atrial,right ventricular volume,function,biomechanics and other characteristics in patients with DM combined with isolated mitral regurgitation,and to explore the relationship between left ventricular and left ventricular in patients with DM combined with isolated mitral regurgitation The linkage effect of atrium and right ventricle and its clinical value.This study was divided into three parts:1.Using CMR tissue tracking technology,quantitative analyze left ventricular global strain in patients with type 2 diabetes mellitus with isolated mitral regurgitation;2)whether isolated mitral regurgitation aggravates left ventricular myocardial damage in patients with diabetes mellitus;the relationship between left ventricular global strain and myocardial injury markers,BMI,metabolic syndrome and other complications;and explore its impact on diabetes mellitus with isolated mitral regurgitation to evaluate the diagnostic value of early myocardial injury in patients with regurgitation.2.Quantitative analysis of left atrial strain changes in T2DM patients with isolated mitral regurgitation,and the relationship between left atrial myocardial strain parameters and the degree of regurgitation.3.Combined with cardiac magnetic resonance tissue tracking technology and cardiac function parameters,investigate the right ventricular structure and function damage in patients with type 2 diabetes mellitus with isolated mitral regurgitation,and analyze the aggravating effect of left ventricular dysfunction.Materials and Methods:The patients in this study were as follows:1.In the part I,157 patients with T2DM were enrolled(98 patients without isolated mitral regurgitation,62.4%;59 patients with mitral regurgitation,37.6%).In T2DM patients with isolated mitral regurgitation,mild mitral regurgitation was found in 21 cases(35.6%),moderate mitral regurgitation in 19 cases(32.2%),and severe mitral regurgitation in 19 cases(32.2%).In addition,52 age and gender matched healthy control volunteers(36 males and 16 females,mean age 55.5 ± 6.8 years,mean BMI 23.1 ± 3.6 kg/m2)were enrolled.2.In the part Ⅱ,153 T2DM patients were enrolled(97 without mitral regurgitation,60.9%;56 with isolated mitral regurgitation,57.8%).The control group included 52 healthy volunteers(male 36,female 16,mean age 55.5 ± 6.8 years,mean BMI 23.1 ± 3.6 kg/m2).3.In the part Ⅲ,157 T2DM patients were included(98 without mitral regurgitation,62.4%;59 with isolated mitral regurgitation,37.6%).In T2DM patients with isolated mitral regurgitation,mild mitral regurgitation was found in 21 cases(35.6%),moderate mitral regurgitation in 19 cases(32.2%),and severe mitral regurgitation in 19 cases(32.2%).52 volunteers were included in the control group(36 males and 16 females,mean age 55.5 ± 6.8 years,mean BMI 23.1 ± 3.6 kg/m2).All subjects underwent 3.0T cardiac MRI cine sequence scanning.Commercial off-line cardiovascular image post-processing software was used for manual delineation and automatic quantitative analysis of all cardiac magnetic resonance images to obtain the structure,function and strain related parameters of each cardiac cavity.The normality of continuous variables was analyzed by Kolmogorov Smirnov test.The normal distribution variables among the three groups were compared by oneway ANOVA and Bonferroni post correction.The differences of normal distribution variables between T2DM patients with and without isolated mitral regurgitation were analyzed by two independent samples t-test.Kruskal Wallis rank test was used to analyze categorical variables and non normal distribution variables.Spearman test was used to analyze the correlation between the parameters.After adjusting for age,gender,BMI,systolic blood pressure and resting heart rate,multiple linear regression was used to analyze the independent correlation factors of global peak strain of left ventricle,left atrium and right ventricle.Results:Part Ⅰ:Compared with the normal control group,the left ventricular mass of T2DM patients without mitral regurgitation was significantly increased[91.2(70.4,115.0)g vs.72.1 ± 19.1 g,P<0.05],while the radial peak strain(PS,31.3 ± 9.8%vs.38.4 ±8.7%),longitudinal PS(-13.3 ± 3.2%vs.-14.8 ± 3.3%)and radial systolic strain rate[PSSR,1.7(1.4,2.1)1/s vs.2.1±0.7 1/s],radial diastolic strain rate[PDSR,-1.9(-2.4,1.3)1/s vs.-2.8±0.9 1/s],circumferential PDSR(1.1±0.3 1/s vs.1.2±0.3 1/s)were all decreased in different degrees(all P<0.05).The left ventricular end diastolic volume[LVEDV,172.6(127.1261.3)ml],end systolic volume[LVESV,93.2(52.6,176.7)mL],left ventricular mass(111.3 ± 40.9 g)of T2DM patients with isolated mitral regurgitation were significantly higher than those of T2DM patients without mitral regurgitation[125.6(104.3,158.4)mL,45.6(35.1,62.2)mL,91.2(70.4,115.0)g]and normal subjects[121.1±27.1 mL,42.7(37.2,49.6)mL,72.1±19.1 g](all P<0.05)。LVEF and left ventricular overall radial PS,PSSR,PDSR,circumferential PS,PSSR,PDSR,and longitudinal PS,PSSR,PDSR were significantly decreased(all P<0.05).In T2DM patients with isolated mitral regurgitation,left ventricular ejection fraction(LVEF)>50%group had lower left ventricular global PS(radial,27.1±6.3%vs.38.4 ± 8.7%;circumferential,16.2 ± 3.0%vs.-19.9 ± 2.7%;longitudinal,11.7 ±2.4%vs.-14.8 ± 3.3%),PSSR[radial,1.6(1.1,1,9)1/s vs.2.1±0.7 1/s],PDSR[radial,-1.6±0.5 1/s vs.-2.8±0.9;circumferential,0.9±0.3 1/s vs.1.2±0.3 1/s;longitudinal,0.7±0.2 1/s vs.0.9(0.8,1.2)1/s]than those in normal subjects.PS,PSSR and PDSR in LVEF<50%group were lower than those in LVEF ≥50%group and normal group in three directions(all P<0.05).LVEF<50%group had lower LV global PS、PSSR、PDSR in three directions compared to controls(all P<0.05).By comparing the different degrees of regurgitation,it was found that the mild mitral regurgitation patients mainly had the decrease of left ventricular global PS and PDSR,and the PSSR only decreased in the radial direction.In the moderate and severe groups,the left ventricular global PS,PSSR and PDSR decreased significantly in three directions(all P<0.05).The degree of regurgitation was slightly negatively correlated with global radial PS(r=-0.304,P=0.019),circumferential PS(r=-0.385,P=0.003)and longitudinal PS(r=-0.399,P=0.002).The course of diabetes was slightly negatively correlated with left ventricular global radial PS(r=-0.301,P=0.021)and longitudinal PS(r=-0.373,P=0.004).Multiple linear regression showed that the degree of regurgitation was an independent correlation factor of left ventricular global radial(β=-0.272),circumferential(β=-0.412)and longitudinal(β=-0.347)PS;the course of diabetes was an independent correlation factor of left ventricular global radial(β=-0.299)and longitudinal(β=-0.347)PS.Part Ⅱ:The prior to atrial contraction volume[LAVpac,41.7(31.0,58.7)ml vs.38.8± 13.2 ml],minimum left atrium volume[LAVmin,27.1(16.5,37.9)ml vs.22.2 ± 8.4 ml]and left ventricular mass[91.6(70.8115.3)g vs.72.1 ± 19.1 g,P<0.05]in T2DM patients without mitral regurgitation were higher than those in normal subjects(all P<0.05).Meanwhile,the peak reservoir strain[PSs,36.5(27.3,45.8)%vs.45.1(36.6,53.7)%],peak conduit strain[PSe,17.3(12.0,25.0)%vs.26.4(21.4,35.3)%],reservoir strain rate[SRs,1.6(0.7,2.3)1/s vs.1.7(-2.0,2.5)1/s],conduit strain rate[SRe,-1.8(-2.5,-1.3)1/s vs.-2.5 ± 1.0 1/s]in patients without mitral regurgitation were lower than those in normal subjects(P<0.05).The left atrial maximum volume(LAVmax),LAVpac,LAVmin and left ventricular mass of T2DM patients with isolated mitral regurgitation were significantly higher than those of T2DM patients without mitral regurgitation and normal subjects,while the LAEF Total,LAEF Passive,LAEF Booster,PSs,peak booster strain(PSa),PSe,SRs and SRe of T2DM patients with isolated mitral regurgitation were significantly lower than those in T2DM patients without mitral regurgitation and normal subjects(all P<0.05).Compared with normal group,LAVmax,LAVpac and LAVmin of LVEF>50%group and LVEF<50%group were significantly increased,EF Total,EF Passive,EF Booster,PSs,PSe and SRe were decreased;EF Total,PSs PSa and SRe of patients with LVEF<50%were significantly lower than those of patients with LVEF>50%(all P<0.05).The left atrial PSs,PSe and SRe of mild mitral regurgitation patients were lower than those of normal people;the left atrial PSs,PSe and SRe of moderate mitral regurgitation patients were lower than those of normal people,and there was no statistical difference between mild mitral regurgitation group and mild mitral regurgitation group;the left atrial PSs,PSe,PSa and SRe of severe mitral regurgitation patients were significantly lower than those of normal people,the left atrial PSs,PSa and SRe of moderate mitral regurgitation patients were lower than those of mild mitral regurgitation patients,and the left atrial PSa was lower than that of moderate mitral regurgitation patients.The degree of mitral regurgitation was negatively correlated with left atrial global PSs(r=-0.390),PSa(r=-0.350)and PSe(r=-0.300)(all P<0.05).LVEF was slightly positively correlated with left atrial global PSs(r=0.327)and PSa(r=0.358)(all P<0.05).There was a slight correlation between left ventricular global radial PS and left atrial global PSs(r=0.423),PSa(r=0.444)and PSe(r=0.312)(all P<0.05).There was a moderate correlation between left ventricular global PS and left atrial global PSs(r=0.531)and PSa(r=0.526),and a slight correlation between left ventricular global PS and PSe(r=0.437)(all P<0.05).Left ventricular longitudinal PS was slightly correlated with left atrial PSs(r=0.421),PSa(r=0.422)and PSe(r=0.381)(all P<0.05).Left ventricular global radial PS was independently correlated with left atrial global PSs(β=1.262)and PSa(β=1.126).There was an independent correlation between left ventricular global PS and left atrial global PSs(β=-0.678),PSa(β=-0.562)and SRs(β=0.357).Part III:The left and right ventricular end diastolic volume,end systolic volume and myocardial mass of T2DM patients with isolated mitral regurgitation were significantly higher than those of normal control group and T2DM patients without mitral regurgitation,while the right ventricular stroke volume and left and right ventricular ejection fraction were significantly lower than those of normal control group and T2DM patients without mitral regurgitation(all P<0.05).Compared with the group with or without mitral regurgitation,the overall circumferential PS[-8.5(-13.3,-3.5)%vs.-12.1(-14.7,-9.3)%,-12.6±3.5%],longitudinal PS[-12.1(-15.6,-6.9)%vs.-18.7±4.3%,-22.6±3.7%],circumferential PSSR[-0.6(-0.8,-0.3)1/s vs.-0.7(-0.9,-0.5)1/s,-0.7±0.2 1/s],longitudinal PSSR[0.8(-1.1,-0.4)1/s vs.-1.1(-1.4,-0.9)1/s,-1.2(-1.4,-1.0)1/s]and longitudinal PDSR[0.9(0.6,1.3)1/s vs.1.2(1.0,1.4)1/s,1.1(1.0,1.3)1/s]of right ventricle in T2DM patients with isolated mitral regurgitation were significantly decreased(all P<0.05),and the overall radial,circumferential and longitudinal PS,PSSR and PDSR of left ventricle were decreased in varying degrees(all P<0.05).Compared with normal people,the radial PS of right ventricle in mild mitral regurgitation group increased,while the longitudinal PS and circumferential PSSR decreased.In moderate mitral regurgitation group,the longitudinal and circumferential PS of right ventricle decreased.There was no significant difference between moderate and mild mitral regurgitation groups.In severe mitral regurgitation group,the right ventricular PS(radial,circumferential,longitudinal),PSSR(circumferential,longitudinal)and PD SR decreased PS(radial,longitudinal)and PSSR(radial,longitudinal)were lower than those in mild group,PS(radial,longitudinal),PSSR(radial),PDSR(radial)were lower than those in moderate group(all P<0.05).In T2DM patients with isolated mitral regurgitation,radial PS(26.7±8.8%vs.21.0±6.2%)and radial PSSR[1.4(1.1,2.1)1/s vs.1.1±0.4 1/s]of right ventricle in RVEF≥45%group were higher than those in normal group(all P<0.05),while longitudinal PS(-15.3±6.5%vs.-22.5±5.1%)and radial PDSR[-1.2±0.5 1/s vs.1.6(-1.9,-0.9)1/s]were lower than those in normal group(all P<0.05).The PS and systolic/diastolic strain rate in RVEF<45%group were significantly lower than those in normal people and RVEF>45%group(all P<0.05).Compared with the normal group,the overall radial and circumferential PS,radial PSSR and PDSR of the right ventricle in the LVEF≥50%group were significantly increased,while the longitudinal PS was significantly decreased;the overall radial PS,circumferential PS,longitudinal PS,radial PSSR,circumferential PSSR,radial and circumferential PDSR of the right ventricle in the LVEF<50%group were significantly lower than those in the LVEF≥50%group and the normal group(all P<0.05).Multiple linear regression analysis showed that right ventricular radial PS was independently correlated with diabetes duration and left ventricular circumferential PS(β=0.258,0.528,P<0.05).Right ventricular circumferential PS was independently correlated with left ventricular longitudinal PS(β=0.448,P<0.05).There was an independent correlation between right ventricular longitudinal PS and left ventricular longitudinal PS(β=0.336,P<0.05).ROC curve showed that when the global radial peak strain of right ventricle was less than 22.96%,the circumferential peak strain was more than-6.095%,and the longitudinal peak strain was more than-11.54%,it could help to identify the impaired right ventricular ejection fraction.Conclusion:① CMR tissue tracking technique could be used to evaluate the structure,function and biomechanical characteristics of left atrium and right ventricular with isolated mitral regurgitation in diabetes mellitus,and to guide the clinical management,early intervention and prognosis improvement of patients with high risk of heart failure.②Isolated mitral regurgitation may aggravate the decrease of left ventricular compliance in diabetic patients,resulting in the decrease of left ventricular function and myocardial strain.The left atrium storage period,catheter stage and active contraction function are damaged.The volume of atrium in each period is significantly increased,and the circumferential and longitudinal stress progressive decrease in the right ventricle,and the radial strain of the right ventricle is shown to rise first and then decrease.③The results showed that the degree of regurgitation,left ventricular mass and LVEF were correlated with the left ventricular peak strain,suggesting that the left ventricular strain damage was more obvious in T2DM patients with isolated mitral regurgitation when the regurgitation degree increased,the left ventricular mass increased and LVEF decreased.④LVEF,regurgitation degree,left ventricular radial and circumferential peak strain were independent of the left atrial storage strain and active systolic strain.⑤The duration of diabetes mellitus,left ventricular peripheral PS were independent of right ventricular radial PS,while longitudinal PS was independent of right ventricular circumferential and longitudinal PS. |
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