| (Part 1)The global left ventricular reverse remodeling after septal myectomy in patients with obstructive hypertrophic cardiomyopathy using echocardiographyObjective:Hypertrophic cardiomyopathy (HCM) is a genetic disease affecting the cardiac muscle. HCM is associated with disease complications that may be profound, with the potential to result in sudden cardiac death (SCD), heart failure, atrial fibrillation and stroke. Left ventricular outflow tract obstruction (LVOTO) is confirmed to be an independent predictor of HCM related death and heart failure. Surgical extended septal myectomy aims at eliminating LVOTO and mitral valve systolic motion (SAM). Previous study has demonstrated that septal myectomy prolong lifetime and quality of life. The present study aims at evaluating the effects of myectomy on global left ventricular reverse remodeling.Methods:This study consisted of 71 consecutive patients with obstructive HCM who underwent transaortic extended septal myectomy between October 2013 and September 2014 in Fuwai Hospital, Beijing. The mean age was 41.0 ± 15.0 years and 47 (66.2%) patients were male. The New York Heart Association (NYHA), brain natriuretic peptide (BNP), proportion of Beta-blocker and its dose were recorded before and latest review (6-24 months after myectomy). Meanwhile, echocardiography evaluation was done including, target anteroseptal thickness, left ventricular outflow tract gradient (LVOTG), SAM, left atrial diameter (LAD), grade of mitral regurgitation (MR), left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular ejection fraction (LVEF), stroke volume (SV), E/E’, left ventricular diastolic function, and left ventricular mass index (LVMI). Forty healthy objects with optimal images were included as control subjects.Results:Compared with healthy objects, target anteroseptal thickness, LVOTG, proportion of SAM, LAD, MR, E/E’, LVMI and LVEF increased, while LVEDV, LVESV and SV decreased in HCM group (all P<0.05). The mean time of latest-review was 10.5 ± 3.9 months. We encountered no cases of SCD, lethal arrhythmia, and stroke during follow-up. After myectomy, clinical variables improved in HCM group. The BNP, proportion of beta-blocker and its dose decreased after myectomy. Of echocardiographic variables, target anteroseptal thickness, LVOTG, proportion of SAM, LAD, MR, E/E’,LVMI decreased, however, LVEDV, LVESV, SV increased after myectomy. Left ventricular diastolic function improved after myectomy; All P<0.05. Echocardiographic △LVMI was significantly larger compared with operative resected mass index (14.5 ± 38.9 vs.3.4 ± 2.0 g/m2, P = 0.028).Conclusions:Transaortic extended septal myectomy relieved symptoms and it is an effective therapy in HCM. It eliminated LVOTO and mitral valve systolic motion, meanwhile MR decreased. After myectomy, left ventricular global function regarding diastolic function improved, however, left ventricular mass decreased spontaneously, which proved global, left ventricular reverse remodeled.(Part 2)Quantification of myocardial strain in hypertrophic obstructive cardiomyopathy and healthy subjects using two-dimensional three-layer speckle trackingObjective:Two-dimensional speckle tracking is a commonly used transthoracic echocardiography (TTE) technique to evaluate myocardial deformation (strain). Three-layer speckle tracking is superior to conventional speckle tracking for its layer-specific analysis as well as manually tracing of epicardial border, which is more fit for asymmetric hypertrophy. It has facilitated a more comprehensive assessment of regional left ventricular (LV) mechanics. Previous studies demonstrated that, histopathologically, there were strong associations between myocyte hypertrophy, disarray, fibrosis, and speckle tracking parameters in patients with HCM. Therefore, our study was to evaluate the value of echocardiographic three-layer speckle tracking in patients with hypertrophic obstructive cardiomyopathy (HOCM) and its potential factors associated with LV strains.Methods:To assess the value of longitudinal strain (LS) and circumferential strain (CS) in three-layer myocardium (endocardial, mid-myocardial, and epicardial layers), 71 patients with HOCM,40 healthy subjects were studied using three-layer speckle tracking imaging. The thickness of each wall segment was calculated and totaled for the 17-segment wall thickness score. Also, we aimed to evaluate the potential factors associated with LV strains. As the extent and distribution of hypertrophy are various, LV morphologic subtypes was defined on echocardiography using basal septal 1/3 to posterior wall ratio:reverse septal curvature (RSC)= ratio>1.3 (extending to mid and distal septum); sigmoid septum (SS)= ratio>1.3 (extending only to basal 1/3), and concentric hypertrophy (CH)= ratio≤ 1.3. The aim of the study was to evaluate left ventricular (LV) strain of morphologic subtypes by three-layer speckle tracking.Results:In HOCM group, the mean age was 41.0 ± 15.0 years, the mean left ventricular ejection fraction (LVEF) was 74.1 ± 8.3%, and the 17-segment wall thickness score was 262.1 ± 42.6; In control group, the mean age was 38.3 ± 17.8 years,26(65%) subjects were males, and the body surface area was 1.6 ± 0.2 m2, there was no significant difference in age, gender, or body surface area between HOCM and control subjects. Compared with healthy subjects, LS was significantly smaller in HOCM:endocardial(-17.9±5.0 versus -25.9±3.1%,P<0.05),mid(-14.6±4.4 versus -22.4±2.9%,P<0.05),epicardial(-11.7±3.9 versus -19.5±2.7%,P<0.05). Percentage endocardial LS dependency in HCM was larger than control(1.58±0.3 versus 1.33±0.1,P<0.05);There was no significant differences between HOCM and control in endocardial CS.Mid(-21.3±4.0 versus -27.4±3.0%,P<0.05), epicardial(-13.6±3.6 versus -20.3±2.8,P<0.05)layer CS were different in HOCM and control,respectively.Percentage endocardial CS dependency in HOCM was larger than control(2.83±0.7 versus 1.92±0.2,P<0.05);17-segment wall thickness score was strongly associated with LV strain in HCM(global LS:r= -0.745,P<0.001; global CS:r= -0.614,P<0.001).There were 55,8,and 8 patients with RSC,SS,and CH.Patients with SS were significantly older(39.2±13.5 versus 54.9±7.3 versus 39.5±23.4 years,for RSC,SS and CH respectively,P = 0.001,Welch), predominantly female(27.3% vs.75% vs.37.5％,for RSC,SS and CH,P = 0.036), and had thinner target anteroseptal thickness(20.5±3.9 versus 16.3±1.2 versus 18.5 ±1.8mm,for RSC,SS and CH,P<0.001);Left ventricular outflow tract gradient, New York Heart Association,brain natriuretic peptide,left atrial diameter,E/E’and LVEF showed to be similar in three groups.Patients with SS had larger global LS (-14.4±4.4 versus -19.2±2.6 versus -12.5±2.9%,for RSC,SS and CH respectively, P = 0.004,ANOVA).Endocardial LS(-17.5±5.0 versus -22.8±2.9 versus -15.5± 3.4%,P = 0.005),mid LS(-14.2±4.4 versus -18.9±2.6 versus -12.3±2.8%,P = 0.004),and epicardial LS(-11.4±3.9 versus -15.7±2.5 versus -9.7±2.5％,P = 0.004) were different in RSC,SS,and CH,respectively.Conclusions:Endocardial CS and LS were greater than that of mid’s and epicardial’s. Although HOCM have preserved LVEF,three-layer myocardial LS seems to be impaired compared with control.Endocardial CS was maintained in compensation for reduction in endocardial LS.17-segment wall thickness score was strongest determinants of LV strain.LV myocardial strain is different in various morphologic subtypes.Patients with SS have significantly larger LV strain than RSC and CH,and SS is more likely to be older,female,and had thinner target anteroseptal thickness.(Part 3)The regional left ventricular reverse remodeling after septal myectomy in patients with hypertrophic obstructive cardiomyopathyObjective:Surgical extended septal myectomy is appropriate treatment for hypertrophic obstructive cardiomyopathy (HOCM) with refractory symptoms. The obstruction removal eliminates symptom and improves survival and quality of life. Early results showed that overall left ventricular (LV) function improved after septal myectomy, including volume, pressure, and myocardial mechanics. However, the mechanism of LV reverse remodeling according to different regions (myectomy site and free wall) has not been assessed using systematic studies. We aimed to evaluate the effects of myectomy on left ventricular regions and the potential factors associated with left ventricular reverse remodeling, using three-layer speckle tracking imaging.Methods:This study consisted of 71 consecutive patients with HOCM who underwent transaortic extended septal myectomy between October 2013 and September 2014 in Fuwai Hospital, Beijing. In 71 patients (mean age:41.0 ± 15.0 years, male 47(66.2%)), clinical and echocardiographic variables were obtained pre-myectomy and latest-review:1) anterolateral, inferolateral, inferior and inferoseptal wall thickness were evaluated by two-dimensional echocardiography; 2) We evaluated the myectomy site (target anteroseptum) and left ventricular free wall longitudinal strain (LS) and circumferential strain (CS) in endocardial, mid-myocardial, and epicardial layers using three-layer speckle tracking.3) Univariate and multivariate linear regression analyses were used for the determinants of latest-review strain. Separate models were constructed for latest-review average LS and CS in the LV free wall and the myectomy site, respectively. The thickness of each free wall segment was calculated and totaled for the free wall thickness score. LV free wall measurements included the following 11 segments (excluding the apical cap): anterior (basal, mid, and apical), anterolateral (basal, mid, and apical), inferolateral (basal, and mid), and inferior (basal, mid, and apical). Forty healthy persons with optimal images were included as control subjects.Results:After septal myectomy, anterior, anterolateral, inferolateral, inferior, inferoseptal wall thickness decreased, although we did not resect these segments. Compared with pre-myectomy, LS increased(-7.0 ± 4.4 versus -8.8 ± 5.0%, P<0.05); however, CS decreased (-19.9 ± 5.4 versus -16.6 ± 6.5%, P<0.05) at the myectomy site after myectomy.For the free wall,LS improved in all three layers post-procedure (-17.7±5.1 versus -21.8±5.8%,-13.8±4.6 versus -16.8±5.2%,-11.0±4.2 versus -13.2±4.6%,-14.2±4.6 versus -17.2±5.2% for endocardial, mid-myocardial,epicardial,and global respectively；P<0.05) ； CS increased in all three layers(-36.2±4.9 versus -38.3±4.5%,-21.5±3.9 versus -23.5±3.9%,-13.9±3.5 versus -15.6±3.8%,-23.9±3.7 versus -25.8±3.7% for endocardial, mid-myocardial,epicardial,and global respectively；P<0.05).Factors independently associated with latest-review free wall strain were free wall thickness score (LS:beta =-0.150,P<0.001；CS:beta=-0.090,P<0.001),age(LS:beta=0.118,P<0.001), and △left ventricular outflow tract gradient(CS:beta = 0.039,P=0.002).Factors independently associated with myectomy site strain were resected thickness(LS:beta = -0.439,P = 0.001；CS:beta = -0.736,P = 0.001),and age(LS:beta = 0.178,P< 0.001).Conclusion:1)LV remodeled regarding reginal function after surgery；2)Our results confirmed that LV reverse remodeling occurred in all three layers of the myocardium and that the mechanism of LV reverse remodeling differed between the myectomy site and the free wall.3)Sufficient relief of obstruction and lower resected thickness in the target anteroseptum lead to more favorable remodeling.Free wall thickness score and age are important factors associated with reverse remodeling.
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