Noncompaction cardiomyopathy in children with congenital heart disease: evaluation using cardiovascular magnetic resonance imaging

Left ventricular non-compaction in patients with single ventricle heart disease

OBJECTIVE

Left ventricular non-compaction is an architectural abnormality of the myocardium, associated with heart failure, systemic thromboembolism, and arrhythmia. We sought to assess the prevalence of left ventricular non-compaction in patients with single ventricle heart disease and its effects on ventricular function.

METHODS

Cardiac MRI of 93 patients with single ventricle heart disease (mean age 24 ± 8 years; 55% male) from three tertiary congenital centres was retrospectively reviewed; 65 of these had left ventricular morphology and are the subject of this report. The presence of left ventricular non-compaction was defined as having a non-compacted:compacted (NC:C) myocardial thickness ratio >2.3:1. The distribution of left ventricular non-compaction, ventricular volumes, and function was correlated with clinical data.

RESULTS

The prevalence of left ventricular non-compaction was 37% (24 of 65 patients) with a mean of 4 ± 2 affected segments. The distribution was apical in 100%, mid-ventricular in 29%, and basal in 17% of patients. Patients with left ventricular non-compaction had significantly higher end-diastolic (128 ± 44 versus 104 ± 46 mL/m2, p = 0.047) and end-systolic left ventricular volumes (74 ± 35 versus 56 ± 35 mL/m2, p = 0.039) with lower left ventricular ejection fraction (44 ± 11 versus 50 ± 9%, p = 0.039) compared to those with normal compaction. The number of segments involved did not correlate with ventricular function (p = 0.71).

CONCLUSIONS

Left ventricular non-compaction is frequently observed in patients with left ventricle-type univentricular hearts, with predominantly apical and mid-ventricular involvement. The presence of non-compaction is associated with increased indexed end-diastolic volumes and impaired systolic function.

Left ventricular non-compaction in a child with bicuspid aortic valve and aortic coarctation

We present the case of a 3-year-old boy with bicuspid aortic valve, aortic coarctation, and left ventricular non-compaction. The diagnosis was made post-natally with ultrasonography and was verified by cardiac MRI. Aortic coarctation was initially repaired surgically. At age 3 months, recoarctation and heart failure developed. Balloon angioplasty was performed with immediate improvement. At age 3 years, the patient remains asymptomatic and normotensive.

The Impact of Concomitant Left Ventricular Non-compaction with Congenital Heart Disease on Perioperative Outcomes

Left ventricular non-compaction (LVNC) is a heterogeneous myocardial disorder characterized by prominent trabeculations and inter-trabecular recesses which may occur in association with congenital heart disease (CHD). To date, few studies have been performed to assess whether the concomitant diagnosis of LVNC affects the outcomes of CHD surgery. A retrospective review of patients with LVNC with CHD (LVNC-CHD), 0-5 years of age, was conducted. Patients with CHD without LVNC (CHD-only) and 0-5 years of age with similar diagnosis distribution were selected for comparison. Perioperative data, including CHD diagnosis, operative course, and postoperative complications were collected and compared between groups. LVNC-CHD was diagnosed in 26 children. Of the 26 with LVNC-CHD, 20 underwent surgery and these patients were compared with 276 CHD-only controls. Median total length of stay in the hospital was 12.5 days (IQR 5.5-63 days) in LVNC-CHD compared to 5 days (IQR 3-10 days) in CHD-only (p < 0.005). Postoperative death, cardiac arrest, or need for ECMO or transplantation occurred in 6/20 (30 %) of the LVNC-CHD patients compared to 3/276 (1 %) of the CHD-only group (p < 0.0001). LVNC-CHD patients had significantly longer hospital length of stay and higher perioperative complications compared to CHD-only patients without myocardial abnormalities. Pediatric cardiac care teams should be cognizant of the possibility of the increased perioperative risk associated with concomitant LVNC. Future prospective studies are warranted.

Left ventricular non-compaction cardiomyopathy

Left ventricular non-compaction, the most recently classified form of cardiomyopathy, is characterised by abnormal trabeculations in the left ventricle, most frequently at the apex. It can be associated with left ventricular dilation or hypertrophy, systolic or diastolic dysfunction, or both, or various forms of congenital heart disease. Affected individuals are at risk of left or right ventricular failure, or both. Heart failure symptoms can be induced by exercise or be persistent at rest, but many patients are asymptomatic. Patients on chronic treatment for compensated heart failure sometimes present acutely with decompensated heart failure. Other life-threatening risks of left ventricular non-compaction are ventricular arrhythmias or complete atrioventricular block, presenting clinically as syncope, and sudden death. Genetic inheritance arises in at least 30-50% of patients, and several genes that cause left ventricular non-compaction have been identified. These genes seem generally to encode sarcomeric (contractile apparatus) or cytoskeletal proteins, although, in the case of left ventricular non-compaction with congenital heart disease, disturbance of the NOTCH signalling pathway seems part of a final common pathway for this form of the disease. Disrupted mitochondrial function and metabolic abnormalities have a causal role too. Treatments focus on improvement of cardiac efficiency and reduction of mechanical stress in patients with systolic dysfunction. Further, treatment of arrhythmia and implantation of an automatic implantable cardioverter-defibrillator for prevention of sudden death are mainstays of therapy when deemed necessary and appropriate. Patients with left ventricular non-compaction and congenital heart disease often need surgical or catheter-based interventions. Despite progress in diagnosis and treatment in the past 10 years, understanding of the disorder and outcomes need to be improved.

cMRI-BED: A novel informatics framework for cardiac MRI biomarker extraction and discovery applied to pediatric cardiomyopathy classification

Background

Pediatric cardiomyopathies are a rare, yet heterogeneous group of pathologies of the myocardium that are routinely examined clinically using Cardiovascular Magnetic Resonance Imaging (cMRI). This gold standard powerful non-invasive tool yields high resolution temporal images that characterize myocardial tissue. The complexities associated with the annotation of images and extraction of markers, necessitate the development of efficient workflows to acquire, manage and transform this data into actionable knowledge for patient care to reduce mortality and morbidity.

Methods

We develop and test a novel informatics framework called cMRI-BED for biomarker extraction and discovery from such complex pediatric cMRI data that includes the use of a suite of tools for image processing, marker extraction and predictive modeling. We applied our workflow to obtain and analyze a dataset of 83 de-identified cases and controls containing cMRI-derived biomarkers for classifying positive versus negative findings of cardiomyopathy in children. Bayesian rule learning (BRL) methods were applied to derive understandable models in the form of propositional rules with posterior probabilities pertaining to their validity. Popular machine learning methods in the WEKA data mining toolkit were applied using default parameters to assess cross-validation performance of this dataset using accuracy and percentage area under ROC curve (AUC) measures.

Results

The best 10-fold cross validation predictive performance obtained on this cMRI-derived biomarker dataset was 80.72% accuracy and 79.6% AUC by a BRL decision tree model, which is promising from this type of rare data. Moreover, we were able to verify that mycocardial delayed enhancement (MDE) status, which is known to be an important qualitative factor in the classification of cardiomyopathies, is picked up by our rule models as an important variable for prediction.

Conclusions

Preliminary results show the feasibility of our framework for processing such data while also yielding actionable predictive classification rules that can augment knowledge conveyed in cardiac radiology outcome reports. Interactions between MDE status and other cMRI parameters that are depicted in our rules warrant further investigation and validation. Predictive rules learned from cMRI data to classify positive and negative findings of cardiomyopathy can enhance scientific understanding of the underlying interactions among imaging-derived parameters.

Knockout of SRC-1 and SRC-3 in Mice Decreases Cardiomyocyte Proliferation and Causes a Noncompaction Cardiomyopathy Phenotype

Noncompaction cardiomyopathy (NCC) is a congenital heart disease that causes ventricular dysfunction and high mortality rate in children. The mechanisms responsible for NCC are still unknown. The steroid receptor coactivator-1 (SRC-1) and SRC-3 are transcriptional coactivators for nuclear hormone receptors and certain other transcription factors that regulate many genes in development and organ function. However, the roles of SRC-1/3 in heart morphogenesis, function and NCC occurrence are unknown. This study aims to examine the spatial and temporal expression patterns of SRC-1/3 in the heart and investigate the specific roles of SRC-1/3 in heart development, function and NCC occurrence. Immunochemical analysis detected SRC-1/3 expressions in the proliferating cardiomyocytes of mouse heart at prenatal and neonatal stages, while these expressions disappeared within two weeks after birth. Through generating and characterizing mouse lines with global or cardiomyocyte-specific knockouts of SRC-1/3, we found ablation of SRC-1/3 in the myocardial lineage resulted in prominent trabeculae, deep intertrabecular recesses and thin ventricular wall and septum. These developmental defects caused a failure of trabecular compaction, decreased internal ventricular dimension, reduced cardiac ejection fraction and output and led to a high rate of postnatal mortality. Collectively, these structural and functional abnormalities closely simulate the phenotype of NCC patients. Further molecular analysis of cardiomyocytes in vivo and in vitro revealed that SRC-1/3 directly up-regulate cyclin E2, cyclin B1 and myocardin to promote cardiomyocyte proliferation and differentiation. In conclusion, SRC-1/3 are required for cardiomyocyte proliferation and differentiation at earlier developmental stages, and their dysfunction causes NCC-like abnormalities in the hearts of newborn and adult mice.

Formation and Malformation of Cardiac Trabeculae: Biological Basis, Clinical Significance, and Special Yield of Magnetic Resonance Imaging in Assessment

Adult and pediatric cardiologists are familiar with variation in cardiac trabeculation. Abnormal trabeculation is a key feature of left ventricular noncompaction, but it is also common in congenital heart diseases and in cardiomyopathies (dilated and hypertrophied). Trabeculae might be a measurable phenotypic marker that will allow insights into how cardiomyopathy and congenital heart disease arise and develop. This will require the linking together of clinical and preclinical information (such as embryology and genetics), with new analysis methods for trabecular quantitation. In adult cardiology several promising quantitative methods have been developed for echocardiography, computed tomography, and cardiovascular magnetic resonance, and earlier cross-sectional caliper approaches have now been refined to permit more advanced assessment. Adaptation of these methods for use in developmental biology might inform on better ways to measure and track trabecular morphology in model organisms.

Fractal Analysis of Myocardial Trabeculations in 2547 Study Participants: Multi-Ethnic Study of Atherosclerosis

PURPOSE

To quantitatively determine the population variation and relationship of left ventricular (LV) trabeculation to LV function, structure, and clinical variables.

MATERIALS AND METHODS

This HIPAA-compliant multicenter study was approved by institutional review boards of participating centers. All participants provided written informed consent. Participants from the Multi-Ethnic Study of Atherosclerosis with cardiac magnetic resonance (MR) data were evaluated to quantify LV trabeculation as a fractal dimension (FD). Entire cohort participants free of cardiac disease, hypertrophy, hypertension, and diabetes were stratified by body mass index (BMI) into three reference groups (BMI <25 kg/m(2); BMI ≥25 kg/m(2) to <30 kg/m(2); and BMI ≥30 kg/m(2)) to explore maximal apical FD (FDMaxApical). Multivariable linear regression models determined the relationship between FD and other parameters.

RESULTS

Included were 2547 participants (mean age, 68.7 years ± 9.1 [standard deviation]; 1211 men). FDMaxApical are in arbitrary units. FDMaxApical reference ranges for BMI 30 kg/m(2) or greater (n = 163), 25 kg/m(2) or greater to less than 30 kg/m(2) (n = 206), and less than 25 kg/m(2) (n = 235) were 1.203 ± 0.06 (95% confidence interval: 1.194, 1.212), 1.194 ± 0.06 (95% confidence interval: 1.186, 1.202), and 1.169 ± 0.05 (95% confidence interval: 1.162, 1.176), respectively. In the entire cohort, adjusted for anthropometrics, trabeculation was higher in African American participants (standardized β [sβ] = 0.09; P ≤ .001) and Hispanic participants (sβ = 0.05; P = .013) compared with white participants and was also higher in African American participants compared with Chinese American participants (sβ = 0.08; P = .01), and this persisted after adjustment for hypertension and LV size. Hypertension (sβ = 0.07; P < .001), LV mass (sβ = 0.22; P < .001), and wall thickness (sβ = 0.27; P < .001) were positively associated with FDMaxApical even after adjustment. In the group with BMIs less than 25 kg/m(2), Chinese American participants had less trabeculation than white participants (sβ = -0.15; P = .032).

CONCLUSION

Fractal analysis of cardiac MR imaging data measures endocardial complexity, which helps to differentiate normal from abnormal trabecular patterns in healthy versus diseased hearts. Trabeculation is influenced by race and/or ethnicity and, more importantly, by cardiac loading conditions and comorbidities. Clinicians who interpret cine MR imaging data should expect slightly less endocardial complexity in Chinese American patients and more in African American patients, Hispanic patients, hypertensive patients, and those with hypertrophy.

Left ventricular noncompaction cardiomyopathy: updated review

The first case of noncompaction was described in 1932 after an autopsy performed on a newborn infant with aortic atresia/coronary-ventricular fistula. Isolated noncompaction cardiomyopathy was first described in 1984. A review on selected/relevant medical literature was conducted using Pubmed from 1984 to 2013 and the pathogenesis, clinical features, and management are discussed. Left ventricular noncompaction (LVNC) is a relatively rare congenital condition that results from arrest of the normal compaction process of the myocardium during fetal development. LVNC shows variability in its genetic pattern, pathophysiologic findings, and clinical presentations. The genetic heterogeneity, phenotypical overlap, and variety in clinical presentation raised the suspicion that LVNC might just be a morphological variant of other cardiomyopathies, but the American Heart Association classifies LVNC as a primary genetic cardiomyopathy. The familiar type is common and follows a X-linked, autosomal-dominant, or mitochondrial-inheritance pattern (in children). LVNC can occur in isolation or coexist with other cardiac and/or systemic anomalies. The clinical presentations are variable ranging from asymptomatic patients to patients who develop ventricular arrhythmias, thromboembolism, heart failure, and sudden cardiac death. Increased awareness over the last 25 years and improvements in technology have increased the identification of this illness and improved the clinical outcome and prognosis. LVNC is commonly diagnosed by echocardiography. Other useful diagnostic techniques for LVNC include cardiac magnetic resonance imaging, computerized tomography, and left ventriculography. Management is symptom based and patients with symptoms have a poorer prognosis. LVNC is a genetically heterogeneous disorder which can be associated with other anomalies. Making the correct diagnosis is important because of the possible associations and the need for long-term management and screening of living relatives.

Implications of genetic testing in noncompaction/hypertrabeculation

Noncompaction/hypertrabeculation is increasingly being recognized in children and adults, yet we understand little about the causes of disease. Genes associated with noncompaction/hypertrabeculation have been identified, but how can these assist in clinical management? Genomic technologies have also expanded tremendously, making testing more comprehensive, but they also present new questions given the tremendous diversity of phenotypes and variability of genomes. Here we present genetic evaluation strategies and assess clinical testing options for noncompaction/hypertrabeculation. We assess genes/gene panels offered by clinical laboratories and the potential for high-throughput sequencing to fuel further discovery. We discuss challenges in cardiovascular genetics, such as interpretation of genomic variants, prediction and disease penetrance.

New imaging modalities to assess cardiac function: not just pretty pictures

PURPOSE OF REVIEW

The following review will focus on the current advances in both echocardiography and cardiovascular MRI (CMRI) in the assessment of cardiac function.

RECENT FINDINGS

The assessment of cardiac function in pediatric patients and in congenital heart disease (CHD) patients has dramatically improved over the last several years. The advancement of transthoracic echocardiography with tissue Doppler imaging, speckle tracking, and three-dimensional echocardiography has enabled strain assessment and the ability to estimate ventricular volumes in these complex patients. In the last few decades, CMRI has become an imaging modality that is now part of the standard tools used for cardiac assessment. With superb two-dimensional and three-dimensional resolution, CMRI allows clear delineation of cardiac and extracardiac structures as well as accurate and reproducible assessment of ventricular volume and function. The most recent and robust contributions of CMRI are its ability to provide characterization of the myocardium and the development of new measurements of global and regional myocardial mechanics and function.

SUMMARY

Recent advances in echocardiography and CMRI allow a better understanding of myocardial mechanics and composition as well as accurate assessment of ventricular volume and global and regional function in the complex and unique anatomy often found in CHD patients.