CMR Based Fast Long-axis Strain And Study In Diagnosis And Prognosis Of HCM

Objective:Strain is an important mechanical index that reflects changes in cardiac function.Traditional myocardial strain measurement relies on complex technical methods,which makes difficult of the clinical application of strain and poor repeatability.Fast long axis strain(FLAS)is a technique for rapid analysis of longitudinal cadiac function based on cardiac magnetic resonance(CMR)cine sequence.It has potential advantages such as simple analysis and good repeatability.However,its application in normal subjects and hypertrophic cardiomyopathy(HCM)has not been explored in China.Materials and Methods:Part 1: Thirty HCM patients,thirty dialted cardiomyopathy(DCM)patients and thirty normal controls(46 men/44 women)were enrolled in this part,and underwent3.0T CMR examnation to aquire the steady state free procession(SSFP)cine images.The FLAS based on CMR cine images was established to analyze the strain of atrium and ventricle.FLAS is compared with feature tracking(FT)technology by its repeatability and feasibility.The ROC curve was used to explore the value of long axis strain in the differential diagnosis between disease and normal people.Part 2: In this study,100 healthy Chinese subjects(43 males,age 48.01±17.25years)were included.FLAS technique was used to analyze their ventricular and atrial long-axis strains,so as to establish the reference value range of ventricular and atrial long-axis strains in healthy Chinese volunteers based on 3.0T CMR,and to explore the influencing factors of FLAS in healthy people.Part 3: In this study,25 patients with left ventricular cardiac hypertrophy due to HCM,hypertension and light chain amyloidosis were enrolled.FLAS was used to analyze in those patiens and compare their ventricular and atrial long axis strains.ROC curve was used to explore the value of long-axis strain in differential diagnosis of cardiac diseases with three hypertrophic phenotypes.In addition,regression analysis was used to explore the factors affecting the long axis strain of ventricle and atrium in disease state.Part 4: In this study,359 HCM patients(198 males,age 47.89 ± 17.25 years)and 100 normal subjects were enrolled.FLAS was used to analyze their ventricular and atrial long axis strains.The combined outcome was defined as a composite of cardiovascular death,resuscitated cardiac arrest,sudden cardiac death(SCD)aborted by appropriate implantable cardioverter-defibrillator discharge(ICD),and hospital admission related to heart failure(HF).Survival analysis and Cox Regression analysis were used to determine the prognostic value of long axis strain of ventricle and atrium in HCM.Results:Part 1: The LAS of the ventricules and atria of patients was lower than those of normal controls,and were well correlated with the ventricular and atrial strain analyzed by FT-CMR and corresponding functional parameters(r: 0.43-0.89,all p<0.05).Compared the FT-CMR,FLAS anlysis required a shorter time and had no lower reproducibility(FLAS ICC: 0.60-0.97,COV: 6.98-17.79;FT-CMR ICC:0.64-0.90,COV: 9.81-23.76).In terms of the value of patient identification,the ventricular and atrial LAS was superior to functional indicators and FT-CMR analysis(AUC of functional indicators: 0.54-0.89;AUC of FLAS: 0.63-0.97;AUC of FT-CMR: 0.58-0.89).Part 2: In this part of the study,we provided the reference values of ventricular an atrial LAS in a group of Chinese normal population(LV-LAS: 16.47±2.43%;RV-LAS: 19.71±3.22%;LA reservoir strain: 36.13±7.71%;LA conduit strain:20.35±6.58%;LA active strain: 15.80±4.06%;RA reservoir strain: 48.77±12.54%;RA conduit strain: 26.82±11.66%;LA active strain: 21.92±6.32%).The LV-LAS,RV-LAS,LA reservoir strain and RA reservoir strain of normal males were lower than those of normal females,while the LA conduit strain of normal males was higher than that of normal females.In addition,we found that age is an important determinant of the ventricular and atrial LAS.Part 3: In this part of the study,the ventricular and atrial LAS of patients in the three groups showed their own specificity with varying degrees of damage,among which the decrease of ventciular and atrial LAS in patients with light chain amyloidosis was the most obvious.The LA reservoir strain and LA conduit strain analyzed by FLAS have statistically differentional value between the hypertensive-LV hypertrophic patients and HCM(AUC=0.75,0.72;p<0.05).The ventricular and atrial LAS(LV-LAS,RV-LAS,LA reservoir strain,LA conduit strain,LA active strain,RA reservoir strain,RA conduit strain,RA active strain)showed statistically significant differential value between the HCM patients and light chain amyloidosis-LV hypertrohic patients(AUC=0.81-0.96;p<0.05).Among the three types of cardiac hypetrophy phenotypes,the differentional value of FLAS was no less than functional indicators.The determinants of the ventricular and atrial LAS in patients were different from those of normal people.Part 4: In this part of the study,during an average follow-up of 40.9 months,59patients(19.7%)reached endpoints.Compared with healthy controls,HCM patiens had impaired LV-LAS,RV-LAS,LA reservoir strain,LA conduit strain,LA active strain,RA reservoir strain,RA conduit strain,while RA active strain was not statistically different from healthy controls.In HCM patients with normal LA diameter or LA volume,LA reservoir strain and LA conduit strain was lower than those of normal people(p<0.05).In HCM patients with increased diameter or LA volume,the degree of damage of LA reservoir strain and LA conduit strain was higher than that of HCM patients with normal LA.Fast LA reservoir strain and LA conduit strain are stronger prognostic factors than LA size,LAVI and the presence of left ventricular late gadolinium enhancement(LGE).Conclusion:FLAS analysis of ventricular and atrial long-axis strain based on CMR cine imges is feasible,and it is more repeatable and lower time-consuming than FT-CMR analysis,and has the ability to identify patients.There were gender and age differences in the long axis strain of ventricle and atrium in normal subjects.In three groups of patients with HCM,hypertensive-LV hypertrophy and light chain amyloidosis-LV hypertrophy,the rapid differentional value of the ventricular and atrial LAS has no lower than the traditional functional parameters.Compared with healthy controls,HCM patients had imapred LAS except for the RA active strain.Especially in patients with normal LA diameter and LA volume,LA reservoir strain and LA conduit strain of FLAS analysis were lower than those of normal controls.While in patienst with enlarged LA dimeter and LA volume,the degree of damage of LA reservoir strain and LA conduit strain was higher than that of patients with normal LA.Fast LA reservoir strain and LA conduit strain are stronger prognostic factors than LA size,LAVI and the presence of left ventricular LGE.