| ObjectiveTo explore the assessment of left ventricular myocardial fibrosis noninvasively using cardiac magnetic resonance（CMR）myocardial strain（MS）and analysis of the correlation between MS and collateral circulation in single coronary artery chronic total occlusion（CTO）.Materiel and methodsFrom January 2015 to August 2017,47 patients（thirty-six male,eleven female,age35-81 years old,mean age is 61.28±9.85 years old）who diagnosed with single coronary artery（right coronary artery,left anterior descending coronary artery or left circumflex coronary artery）CTO by coronary angiography with duration>3 months were enrolled in this study.And all patients completed CMR imaging within one week in our hospital.All the study objects performed CMR imaging at 1.5T MR scanner,including left ventricular long axis,inflow and outflow tract,four-chamber,and whole left ventricular（from apex to base）short axis cine with fast imaging employ steady state acquisition.And left ventricular late gadolinium enhancement（LGE）in short axis,long axis and four-chamber were performed.All dates were measured by CVI 42（cvi42 v5.0,Circle Cardiovascular Imaging,Alberta,Canada）.The strain parameters of left ventricular each myocardial segment（AHA16 segment model）were calculated automatically by software:radial peak strain（RS）,circumferential peak strain（CS）,longitudinal peak strain（LS）,systolic radial strain rate（SRSR）,systolic circumferential strain rate（SCSR）,systolic longitudinal strain rate（SLSR）,diastolic radial strain rate（DRSR）,diastolic circumferential strain rate（DCSR）,diastolic longitudinal strain rate（DLSR）,the percentage of each segment LGE in the corresponding segment and the volume of each segment of left ventricular myocardium.The collateral circulation of 47 patients with single coronary artery CTO diagnosed by coronary angiography was evaluated by experienced cardiologists.The distal collateral angiography was evaluated by Rentrop grading.The 2-3 grades of collateral circulation were classified as well-developed groups.Grade 0-1 were classified as dysplastic groups.All date was analyzed by SPSS 22.0 software.Intra-and inter-group consistency analysis of MS measurements were performed using ICC test.In the territories supplied by single CTO vessel,the correlation between MS parameters and LGE,collateral circulation,and the correlation between LGE and collateral circulation are analyzed by Pearson correlation analysis.The differences of MS parameters between LGE positive group and negative group,well-developed collateral circulation group and dysplasia group were analyzed.Independent sample T test was used for normal distribution,and Mann-Whitney U test was used for non-normal distribution.The diagnostic efficiency of MS parameters was assessed by receiver operating characteristic curve（ROC）analysis.P<0.05 was defined as statistical significant.Results1.The MS parameters in 47 patients with single-branch coronary artery CTO were analyzed.Except for the intra-group ICC value of DLSR（0.621）,the intra-group and inter-group ICC values for other MS parameters were all above 0.75.Consistency of CS was the highest and the ICC value reached 0.99.2.LGE positive group included 29 cases（61.70%）,LGE negative group 18 cases（39.30%）.In the territories supplied by single CTO vessel,the RS,CS,LS,SRSR,DRSR in LGE negative group was significantly higher than LGE positive group(28.97±10.55%vs.20.29±9.11%,p=0.005;-18.54±3.94%vs.-13.97±5.09%,p=0.002;-10.72±4.33%vs.-7.56±3.80%,p=0.012;1.48±0.68 s-1 vs.1.04±0.61 s-1,p=0.025;-2.01±1.08 s-1 vs.-1.23±0.81 s-1,p=0.008).Differences of CS were most significant（p=0.002）.3.In the territories supplied by single CTO vessel,the RS,CS,SRSR,SCSR,DRSR,DCSR were negatively correlated with LGE（r=-0.48,p=0.001;r=-0.49,p=0.001;r=-0.48,p=0.001;r=-0.33,p=0.025;r=-0.39,p=0.007;r=-0.34,p=0.018）.Correlation of CS is the strongest（p=0.001,r=-0.49）.4.When CS was used to assess positive LGE in the territories supplied by single CTO vessel,area under the curve was 0.77.The optimal cut-off value of CS for positive LGE was-16.97%,sensitivity 75.86%,specificity 72.22%,positive predictive value81.48%,negative predictive value 65.00%,respectively.5.There was no correlation between MS parameters and collateral circulation in the territories supplied by single CTO vessel（all P>0.05）.ConclusionCMR MS can quantitatively analyze left ventricular myocardial deformation in the patients with single CTO and preliminarily predict myocardial LGE in the territories supplied by single CTO vessel.CS is an ideal MS indicator for predicting the presence or absence of LGE in the territories supplied by single coronary CTO vessel.The optimal cut-off value for CS is-16.97%. |
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