| Purpose To investigate left ventricular(LV)myocardial fibrosis in patients with hypertrophic cardiomyopathy(HCM)using cardiac magnetic resonance(CMR)myocardial strain(MS)noninvasively and find the best MS parameters for predicting myocardial fibrosis.Materiel and methods From December 2011 to August 2018,41 patients with HCM diagnosed by clinical and echocardiography in our hospital were enrolled in this study(22 males and19 females;mean age,56.02±13.21 years;range,43-69 years).All the study objects were performed at 3.0T MR scanner,including LV long axis,four-chamber and LV short axis cine with fast imaging employ steady state acquisition.Left ventricular late gadolinium enhancement(LGE)images including LV short axis,long axis and four-chamber were performed.All data were measured by Report Card4.0 and CVI42 software.(1)LV structure and function parameters including: LV end-diastolic volume(LVEDV),LV end-systolic volume(LVESV),LV ejection fraction(LVEF),LV mass and cardiac output(CO).maximum LV end diastolic wall thickness(LVWT),LGE range.LVEDV,LVESV and LVmass were indexed.(2)LV MS parameters of myocardial segment: radial strain(RS)and radial peak systolic strain rate(RSSr),circumferential strain(CS)and circumferential peak systolic strain rate(CSSr),longitudinal strain(LS)and longitudinal peak systolic strain rate(LSSr).(3)LV global myocardial MS parameters: global radial strain(GRS)and its peak systolic strain rate(GRSSr),global circumferential strain(GCS)and its peak systolic strain rate(GCSSr),global longitudinal strain(GLS)and its peak systolic strain rate(GLSSr).According to existence of LGE in global myocardial,the patients were divided into global myocardial LGE(+)group and global myocardial LGE(-)group.According to existence of LGE in each myocardial segment,all the myocardial segments were divided into segmental LGE(+)group and segmental LGE(-)group.The data were analyzed by SPSS17.0 software.Intra-and Interobserver variabilty for reproducibility of MS measurements was assessed using intraclass correlation coefficienct(ICC).In terms of global myocardial LGE,the comparisons of age,body surface area,body mass index,heart rate,LV structure and function parameters and global strain parameters between global myocardial LGE(+)group and LGE(-)group were performed using T-test in accordance with normal distribution or non-parametric test.Categorical variables(sex,type of obstruction,valvular regurgitation and family history)between both groups were analysed by Fisher's exact test.In the case of each myocardial segment,the differences of segmental MS parameters between segmental LGE(+)group and segmental LGE(-)group were tested by independent T-test.Pearson's correlation was utilized to evaluate relationship of segmental MS parameters with LVWT and LGE of the corresponding segment.ROC curve was analyzed for predicting myocaridal segmental LGE(+)by MS parameters.P< 0.05 was considered a statistically significant difference for all comparisons.Results(1)30 HCM patients were randomly selected.Global myocaridal strain and strain rate including GRS,GCS,GLS,GRSSr,GCSSr,GLSSr show excellent inter-and intraobserver agreement(ICC>0.75).(2)For the whole myocardium of LV,LGE(+)group included 22 cases(53.66%)and LGE(-)group included 19 cases(46.34%).There was no difference in age,sex,type of obstruction,body surface area,body mass index,heart rate,valvular regurgitation and family history between the two groups.LVmass index in LGE(+)group was lower than that in LGE(-)group(68.18±27.42g/m2 vs 95.61 ±31.17g/m2,P=0.005).There was no significant difference in LVEDV index,LVESV index,LVEF,CO and LVWT between the two groups(P>0.05).GCS,GLS,GLSSr in LGE(+)group were significantly lower than that in LGE(-)group(GCS,-11.43±3.79% vs-14.50 ±3.64%,P=0.011;GSL,-5.93±2.54% vs-8.89±3.03%,P=0.002;GLSSr,-0.39±0.15s-1 vs-0.53±0.17s-1,P =0.009).(3)In the case of each segment of LV myocardium,there were 656 segments in 41 patients,148 segments with LGE(+)and 508 segments with LGE(-).Comparisons of segmental MS parameters between segmental LGE(+)group and segmengtal LGE(-)group showed: RS,CS,LS,RSSr,CSSr,LSSr in segmental LGE(+)group were significantly lower than that in segmental LGE(-)group(RS15.94±17.17%vs22.52±17.65%,P=0.000;CS-11.74±4.49%vs-14.28±5.61%,P=0.000;LS-8.04±6.18% vs-9.03±4.93%,P=0.044;RSSr 0.95±1.08s-1 vs 1.33±1.25s-1,P=0.001;CSSr-0.83±0.32s-1 vs-0.94±0.37s-1,P=0.001;LSSr-0.58±0.37s-1 vs-0.67±0.40s-1,P=0.008).MS parameters in all directions were negatively correlated with LGE(RS,r=-0.183,P=0.000;CS,r=-0.225,P=0.000;LS,r=-0.085,P=0.030;RSSr,r=-0.148,P=0.000;CSSr,r=-0.182,P=0.000;LSSr,r=-0.100,P=0.010).The correlation between CS and LGE was the best(r=-0.225,P=0.000).The area under the ROC curve of LGE(+)predicted by CS was 0.634,95% confidence interval:0.587-0.682.The sensitivity was61.6% and the specificity was 61.8% when CS was-12.63%.(4)For each segment of LV,RS,CS,LS,CSSr showed negative correlation with LVWT of the corresponding segment(RS,r=-0.369,P=0.018;CS,r=-0.487,P=0.001;LS,r=-0.405,P=0.009;CSSr,r=-0.395,P=0.011).The correlation between CS and LVWT was the best.Conlusion CMR MS can be used to quantitatively analyze myocardial deformation of LV in HCM patients and preliminarily predict myocardial fibrosis in hypertrophic areas.CS is a relatively ideal MS parameter to predict the existence of myocardial LGE.The optimal cutoff value for CS is-12.63%. |
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