| Detection of Myocardial Infarction Using Native T1 Mapping in a Swine Model:A Validation StudyIntroduction:Myocardial infarction(MI)is a major cause of premature morbidity and mortality.Comprehensive evaluation of the location and area of MI is important for clinical management and risk stratification.Late gadolinium enhancement(LGE)acquired by cardiovascular magnetic resonance(CMR)is considered as the in-vivo gold standard for detection and quantification of MI with excellent histological validation.However,the gadolinium contrast agents are contraindicated in patients with chronic end-stage kidney disease,which account to one fifth of the patients' cohort presenting with acute myocardial infarction.Native T1 mapping has emerged as a novel technique which permits quantitative characterization of myocardium without the need for contrast agent.Thus,T1 mapping can be an appropriate and safe technique for MI patients who suffer from kidney disease.Our aim in this study using a porcine model was to determine the diagnostic accuracy of in-vivo native T1 mapping and to determine infarct location and size against the reference standard of ex-vivo histology finding.Methods:MI was induced in 12 Chinese mini pigs.MRI study was performed two weeks after the MI.Afterwards,the hearts were excised and stained with TTC.The T1 value and the presence or absence of LGE were recorded in each AHA segments.The T1 value of the remote and infarcted myocardium were compared.Bland-Altman analysis was performed to estimate the agreement of the observers and the infarcted size measured by T1 map against LGE and histological findings.Simple linear regression was performed to estimate the correlation between the techniques with respect to infarct size.Using TTC staining as the gold standard for myocardial infarction,the accuracy of native T1 maps and LGE to detected infarcted myocardium at segmental level were measured on ROC analysis.The best cut-off value for T1 map to detect infarcted myocardial segment were determined.Results:The TTC staining and MRI study successfully performed on 10 mini pigs.The mean left ventricular end-diastolic volume and the mean LVEF were 50.1 ± 6.5 ml and 41.83 ± 7.46%.The T1 value of infarct area was significantly higher than that of the remote area(1334 ± 110 msec vs 996 ± 51 msec,P<0.0001).The average difference between T1 of infarcted and normal myocardium was 337.43 ± 119.48 mesc.The percentage change of signal intensity on LGE images was 402.00 ± 132.24%,which was about 17-fold higher than that of the T1 value.The infarcted myocardium is identified successfully by software on both LGE and T1 maps.The infarct size assessed by T1 mapping correlated significantly with that assessed by LGE(y = 1.2934 + 0.9091x,R2 = 0.980,p<0.0001)and TTC staining(y =-0.1186 + 0.906x,R2 = 0.963,p<0.0001).Bland-Altman analysis showed good agreement between T1 maps and LGE images for measuring the infarct size(limits of agreement =-1.470%± 0.56%);and there was also good agreement in infarct size detected by T1 maps and TTC staining(limits of agreement =-3.123%± 1.08%).ROC analysis showed that A T1 value of 1124 milliseconds had the highest Youden index(0.719)with sensitivity of 75.6%and specificity of 96.3%to detect myocardial infarction defined by TTC staining.While the LGE images had sensitivity of 90.2 and specificity of 91.7.The area under the curve was 0.89 ± 0.02 for T1 mapping,and 0.91 ± 0.02 for LGE.There was no significant difference between the two techniques to detect MI segments(z statistic:0.31,p = 0.756).Conclusions:Our study demonstrated that T1 mapping is feasible for the accurate assessment of the size and determine the location in MI swine model.This technique has potential utility as a viable alternative to LGE,particularly in patients with end-stage of chronic kidney disease.Our study justifies the need for clinical translation of this in-vivo contrast free technique.The Clinical and Prognostic Significance of LGE Pattern in DCMIntroduction:Dilated cardiomyopathy(DCM)is characterized by enlargement of ventricular chamber and impaired systolic function with patent coronary arteries.DCM patients usually presents with congestive heart failure.In addition,the disease is the most common reason for cardiac transplantation.Previous studies showed that late gadolinium enhancement(LGE)is associated with adverse outcome in DCM.However,the clinical and prognostic significance of different LGE pattern remains unknown.Therefore,by systematically reviewing the clinical and CMR data and patient follow-up,we aim to investigate the clinical and prognostic characteristics of DCM patients with different LGE pattern.Methods:Patients had diagnosis of DCM and had CMR study were consecutively enrolled from January 2012 to December 2013.Patients were divided into four groups according to the pattern of LGE(LGE absent group,focal LGE group,midwall striate LGE group and infarct-like LGE group).The clinical characteristics and CMR parameters were collected and compared.The patients were followed up for cardiac death,cardiac transplantation,rehospitalization and ICD implantation.Kaplan-Meier curve were used to compare the frequency of the adverse events.Cox proportional hazards regression analysis was used to determine the hazard ratio of LGE for the prediction of adverse events.Results:A total of 384 patients were enrolled,whom were divided as LGE absent group(168 patients,43.75%),focal LGE group(38 patients,9.9%),mid-wall striate LGE group(126 patients,32.81%)and infarct-like LGE group(32 patients,8.3%).The main age of the enrolled patients was 45 ± 12.7 years-old.Patients with LGE had higher NYHA functional class,of whom,mid-wall striate LGE group had more patients with higher NYHA functional class(41%for NYHA functional class ? and 23%for class ?).While 39%and 5.5%of patients had NYHA functional class ? and ? in LGE absent group,respectively.The main LVEF and LVEDV of DCM patients was 25.24 ± 8.58%and 270± 102.18ml.There were significant differences in LVEF,LVEDV,LVESV,LVEDVi and LVESVi among the groups(all p value less than 0.001).Compared with LGE absent group,patients with LGE had lower LVEF,higher LVEDV,LVESV,LVEDVi and LVESVi.During the follw-up,367 DCM patients had 117 adverse cardiovascular events.The most common event was rehospitalization due to the progression of heart failure(10.1%).Besides,21 patients had cardiac transplantation(6.23%)and 14 patients had cardiovascular death(4.15%).Log-rank test showed that the rate of composite endpoint of cardiac death and transplantation were significant different among the groups(focal LGE group vs mid-wall striate LGE group:X2= 6.8583,p = 0.009;mid-wall striate LGE group vs infarct-like LGE group:X2= 5.84,p = 0.0156;focal LGE group vs infarct-like LGE group:X2=14.46 p = 0.0001).Log-rank test showed that the rate of composite endpoint of adverse events were significant different among the groups as well(focal LGE group vs mid-wall striate LGE group:X2= 9.242,p = 0.0024;mid-wall striate LGE group vs infarct-like LGE group:X2 = 8.23,p =0.003;focal LGE group vs infarct-like LGE group:X2 = 18.68,p<0.0001).Univariable Cox regression showed that infarct-like LGE had the highest risk for composite endpoint of adverse events(infarct-like LGE vs focal LGE:HR = 7.977,95%CI:2.901-21.94,p=0.0001;infarct-like LGE vs mid-wall striate LGE:HR = 2.202,95%CI:1.223-3.964,p=0.0085).While focal LGE had the lowest risk(focal LGE vs mid-wall striate LGE:HR = 0.2761,95%CI:0.1050-0.7259,p=0.0091).Using mid-wall LGE as a reference,multi-variable Cox regression showed that infarct-like LGE was an independent predictor for adverse cardiovascular events(HR=1.828,95%CI:1.005-3.327,p=0.0482).Mid-wall striate LGE was not a significant predictor for advers cardiovescular events compared with focal LGE(HR=2.770,95%CI:0.9099-8.431,p=0.0730).Conclusions:The most common pattern of LGE in DCM patients was mid-wall striate LGE.Patients with difference LGE pattern had different NYHA functional class.Compared with mid-wall LGE,patients with infarct-like LGE had a worse outcome and patients with focal LGE had a better outcome.LGE pattern is associoated with adverse cardiovascular events.Prognostic Significance of LGE in Children with DCMIntroduction:Dilated cardiomyopathy(DCM)is the most common form of cardiomyopathy in children and the most common reason for cardiac transplantation.Late gadolinium enhancement(LGE)detected by cardiovascular magnetic resonance can be used as a predictor of adverse events in adult dilated cardiomyopathy patients.However,the evidence of this predictor in DCM children is still limited.Therefore,the aim of the present study is to investigate the clinical and prognostic significance of LGE in children with DCM by systematically reviewing the clinical data and follow-up of the children with DCM.Methods:Patients under 18 years old who had diagnosis of DCM and had CMR study were consecutively enrolled from January 2010 to December 2015.CMR protocol included ventricular functional assessment and LGE imaging for fibrosis detection.DCM children were divided into two groups according to the presence or absence of LGE.The clinical characteristics and CMR parameters were collected and compared.The patients were followed up for cardiac death,transplantation and rehospitalization.Kaplan-Meier curve were used to compare the frequency of the adverse events.Cox proportional hazards regression analysis was used to determine the hazard ratio of LGE for the predict of adverse events.Results:A total of 58 DCM patients under 18 years old were enrolled,of which,28 patients(48.2%)had LGE and 30 patients did not have LGE(51.7%).The main age of the patients was 13.9 ± 3.0 years old and 39 patients(67.24%)were male.There were no significant differences in patients' age(13.89 ± 3.40 for LGE+ group vs 13.96 ± 2.64 for LGE-group,p=0.927)and gander(17[60.7%]males for LGE+ group vs 22[73.3%]males for LGE-group,p=0.306).A significantly higher NYHA functional class was found in the LGE+ group(p=0.039).With respect to left ventricular functional and volume parameters.The main LVEDVi and LVEF of all enrolled patients were 165.61 ± 59.46 ml/m2 and 25.72± 12.33%.LGE+ group had a significant higher LVEDVi(181.55 ± 64.65 ml/m2 for LGE+group vs 150.73 ± 50.83 ml/m2 for LGE-group,p = 0.048)and LVESVi(149.66 ± 58.49 ml/m2 for LGE+ group vs 110.13 ± 52.65 ml/m2 for LGE-group,p = 0.009).The LVEF of LGE+ group was lower(21.74 ± 11.84%for LGE+ group vs 29.43 ± 11.79%for LGE-group,p=0.016).There were no significant differences in the medication and the prevalence of abnormal ECG finding including non-sustained ventricular tachycardia,PVC and PAC.During the follow-up,there was 27 adverse events reported.Log-rank test showed that LGE+ group had a significant higher rate for cardiac death(X2 = 7.709,p =0.005),with a HR of 6.44(95%CI:1.423-31.01).The rate of cardiovascular composite endpoint event was significant higher in LGE + group(Log-rank test X2 = 6.583,p<0.0103)with a HR of 2.742(95%CI:1.22-6.12).There was no significant difference in the risk of cardiac transplantation between the groups(log-rank X2 = 0.863,p = 0.352).Conclusions:Patients with LGE had a higher LV volume,worse cardiac function and outcome compared with those without LGE.Fibrosis detected by LGE has clinical and prognostic significance in DCM children. |
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