CMR Study In Patients With Hypertrophic Cardiomyopathy-Re-recognition Of Left Atrial Remodeling

PurposeTo evaluate remodeling and dysfunction of left atrial(LA)in hypertrophic cardiomyopathy(HCM)patients by cardiac magnetic resonance(CMR)and compare with healthy volunteers,and explore under the influence factors such as left ventricular(LV)parameters,left ventricular outflow trace(LVOT)obstruction,extend of late gadolinium enhancement(LGE),blood brain natriuretic peptide(BNP)level and atrial fibrillation the degree of remodeling and dysfunction of LA in HCM,and identify the feature and clinical significant of LA remodeling and dysfunction by comprehensively and accurately evaluate LA.Materiel and methodsForty-six HCM patients who completed conventional CMR cine scan(36 patents among them performed LGE image)were enrolled in this study from December 2011 to December 2016,all the HCM patients were clinical diagnosed while hospitalization or clinic service in the First Affiliated Hospital of Dalian Medical University(twenty-five male,twenty-one female,age 25-78 years old,mean age is 59.02+11.99 years old,mean course of disease is 6.67 + 6.85 years).Thirteen patients were diagnosed with LVOT obstruction by echocardiogram and 33 cases was non-obstructive patients.Thirteen patients were diagnosed with atrial fibrillation before CMR scan.Twenty-three healthy volunteers were enrolled who completed conventional CMR cine scan from December 2014 to December 2016(eleven male,twelve female,age 40-75 years old,mean age is 55.04± 10.13 years old).All the study objects were performed at 3.0T MR scanner,including two-chamber,four-chamber,and LV short axis cine with fast imaging employ steady state acquisition(FIESTA),Among these,in 36 HCM patients 2D myocardial delayed enhancement(2D MDE)were performed.All dates were measured by ReportCard 4.0 software of GE(AW4.4)work station.LA parameters:LA end-diastolic volume(LAVmax),LA pre-atrial contraction volume(LAVpre-A),LA end-systolic volume(LAVmin),LA ejection fraction(LAEF),consist of LA total EF(LAEF-T),LA passive EF(LAEF-P),LA active EF(LAEF-A);and LV parameters:LV end diastolic volume(LVEDV),LV end systolic volume(LVESV),LVEF,LVMASS,cardiac output(CO),maximum LV end diastolic wall thickness(LVWT),extend of late gadolinium enhancement(LGE)were measured.All data was indexed to body surface area,both indexed values and absolute values were enrolled into analysis.All date was analyzed by SPSS 17.0 software.Comparison of LA,LV parameters between HCM patients and healthy volunteers was analyzed by independent sample t-test or non-parametic test.Analysis LA parameters influenced by LV parameters,LVOT obstruction,extend of LGE,blood BNP level and LA fibrillation were performed by independent sample t-test,non-parametic test,Shapiro-Wilk test,Spearman correlation analysis.Diagnostic value of LA parameters to atrial fibrillation was performed by ROC curve analysis.P<0.05 was defined as statistical significant.Results1.HCM patients showed greater LVMASS and LVMASSi than healthy volunteers,both of them have statistical significance(p<0.05).LAVmax,LAVmaxi,LAVpre-A,LAVpre-Ai,LAVmin,LAVmini were greater in HCM patients than healthy volunteers,while LAEF-T,LAEF-P,LAEF-A were lower in HCM patients,all the differences were statistically significant(p<0.05).2.Significant correlations were observed between LVWT and LAVmax,LAVmaxi,LAVpre-A,LAVpre-Ai(r=0.35,p=0.02;r=:0.35,p=0.02;r=0.42;p=0.00;r=0.39,p=0.01)in HCM patients.Significant correlations were observed between LAVpre-A and LVMASS,LVMASSi(r=0.29,p=0.047;r=0.34,p=0.02)in HCM patients.Significant correlations were observed between LVEDVi and LAVpre-A(r=0.34,p=0.02)in HCM patients.Significant correlations were observed between LAEF-A and LVEDV,LVESV(r=0.33,p=0.02;r=0.31,p=0.03)in HCM patients.Significant correlations were observed between LVEF-P and LVWT(r=-0.34,p=0.02)in HCM patients.3.HCM patients with LVOT obstruction showed greater LVWT,LVMASS,LVMASSi than without LVOT obstruction(p<0.05).LA structural and functional parameters was sirmilar in HCM patients with and without LVOT obstruction(p>0.05).4.Significant correlations were observed between LGE extend and LAVmax(r=0.37,p=0.03)in HCM patients.LAVmax.LAVmaxi.LAVpre-A was significantly increased in HCM patients with LGE extend>5%than LGE extend<5%(p<0.05).5.In HCM patients,blood BNP level was positively correlated with LAVmax,LAVmaxi,LAVpre-A,LAVpre-Ai,LAVmin,LAVmini(r=0.39,p=0.02;r=0.51,p=0.00;r=0.50,p=0.00;r=0.55,p=0.00;r=0.52;,p=0.00;r=0.55,p=0.00)and negatively correlated with LAEF-T,LAEF-P,LAEF-A(r=-0.53,p=0.02;r=-0.52,p=0.00;r=-0.44,p=0.01).Patients with BNP level>100pg/ml showed greater LAVmaxi,LAVpre-Ai,LAVmini and lower LAEF-T,LAEF-P,LAEF-A,all the differences were statistically significant(p<0.05).6.Patients with atrial fibrillation showed greater LAVmin,LAVmini but lower LAEF-T,LAEF-A,all the differences were statistically significant(p<0.05).ROC curve showed excellent diagnostic value of LAVmin,LAVmini,LAEF-T,LAEF-A to atrial fibrillation,area under the curve is 0.81,0.78,0.77,0.75 respectively.ConclusionThis study evaluated multi-paremeters of LA in HCM patients,showed the feasibility of CMR to evaluate LA remodeling and dysfunction comprehensively and quantitatively.The remodeling and dysfunction of LA in HCM patients than healthy volunteers were observed,and this study also showed the remodeling and dysfunction of LA in HCM patients was practicable to reflect blood BNP level and secondary atrial fibrillation.There is a good clinical application prospect of study in LA by CMR.