Left ventricular noncompaction

Fractal analysis: Left ventricular trabecular complexity cardiac MRI adds independent risks for heart failure with preserved ejection fraction in participants with end-stage renal disease

PURPOSE

To measure left ventricular (LV) trabecular complexity by fractal dimension (FD) in patients with end-stage renal disease (ESRD), and assess whether FD was an independent risk factor for heart failure with preserved ejection fraction (HFpEF), or a significant predictor for adverse outcome in this population.

METHODS

The study retrospectively enrolled 104 participants with ESRD who underwent 3.0 T cardiac magnetic resonance imaging (MRI) from June 2018 to November 2020. LV trabeculation was quantified with fractal analysis of short-axis cine slices to estimate the FD. Logistic regression analyses were used to evaluate FD and cardiac MRI parameters and to find independent risk predictors. Cox proportional hazard regression was used to investigate the association between FD and MACE.

RESULTS

LV FD was higher in in the HFpEF group than those in the non-HFpEF group, with the greatest difference near the base of the ventricle. Age, minimum left atrial volume index, and LV mean basal FD were independent predictors for HFpEF in patients with ESRD. Combining the mean basal FD with typical predictive factors resulted in a C-index (0.902 vs 0.921), which was not significantly higher. Same improvements were found for net reclassification improvement [0.642; 95% confidence interval (CI), 0.254-1.029] and integrated discrimination index (0.026; 95% CI, 0.008-0.061). Participants with a LV global FD above the cutoff value (1.278) had higher risks of MACE in ESRD patients.

CONCLUSIONS

LV trabecular complexity measured by FD was an independent risk factor for HFpEF, and a significant predictor for MACE among patients with ESRD.

Case report: Myocardial noncompaction causing massive cerebral infarction in 1 patient with eyelid edema as an early manifestation and literature review

Objective

To summarize and analyze the early clinical manifestations, risk factors, treatment and prognosis of myocardial noncompaction in children, and to provide scientific basis for early and effective intervention.

Methods

Combined with a case of myocardial noncompaction with massive cerebral infarction in a child, the related research reports of myocardial noncompaction in children were analyzed retrospectively.

Results

Myocardial noncompaction in children is cardiomyopathy caused by abnormal myocardial compaction during embryonic development. Feeding intolerance, dyspnea, chest tightness, fatigue, eyelid edema and other non-specific manifestations may occur in the early stage. It is easy to miss the diagnosis and misdiagnosis in clinical diagnosis and treatment, leading to intractable heart failure, nausea and arrhythmia, thromboembolism and even sudden death and other serious complications. Early diagnosis, symptomatic treatment, control of complications and regular follow-up can prevent the occurrence of serious complications and reduce mortality.

Conclusion

There is no specific clinical manifestation in the early stage of myocardial noncompaction in children. If it is not detected early and treated symptomatically, the prognosis is poor and the mortality is high. Therefore, clinicians should fully improve the understanding of the early clinical manifestations of this disease, give early diagnosis and early intervention to children, reduce the occurrence of serious complications and improve the survival rate.

Left ventricular noncompaction: a disorder with genotypic and phenotypic heterogeneity-a narrative review

Background and Objective

Left ventricular noncompaction (LVNC) is a cardiomyopathy characterized by excessive trabecular formation and deep recesses in the ventricular wall, with a bilaminar structure consisting of an endocardial noncompaction layer and an epicardial compacted layer. Although genetic variants have been reported in patients with LVNC, understanding of LVNC and its pathogenesis has not yet been fully elucidated. We addressed the latest findings on genes reported to be associated with LVNC morphogenesis and possible pathologies to understand the diverse spectrum between genotype and phenotype in LVNC. Also, the latest findings and issues related to the diagnosis of LVNC were summarized.

Methods

This article is written as a commentary narrative review and will provide an update on the current literature and available data on common forms of LVNC published in the past 30 years in English through to May 2022 using PubMed.

Key Content and Findings

Familial forms of LVNC are frequent, and autosomal dominant mode of inheritance has been predominantly observed. Several of the candidate causative genes are also mutated in other cardiomyopathies, suggesting a possible shared molecular and/or cellular etiology. The most common gene functions were sarcomere function whereas genes in mice LVNC models were involved in heart development. Echocardiography and cardiac magnetic resonance imaging (CMR) are useful for diagnosis although there are no unified criteria due to overdiagnosis of imaging, poor consistency between techniques, and lack of association between trabecular severity and adverse clinical outcomes.

Conclusions

This review reflects the current lack of clarity regarding the pathogenesis and significance of LVNC and showed the complexity of imaging diagnostic criteria, interpretation of the role of LVNC as a cause, and uncertainty regarding the specific genetic basis of LVNC.

Arrhythmias and Heart Failure in Pregnancy: A Dialogue on Multidisciplinary Collaboration

The prevalence of CVD in pregnant people is estimated to be around 1 to 4%, and it is imperative that clinicians that care for obstetric patients can promptly and accurately diagnose and manage common cardiovascular conditions as well as understand when to promptly refer to a high-risk obstetrics team for a multidisciplinary approach for managing more complex patients. In pregnant patients with CVD, arrhythmias and heart failure (HF) are the most common complications that arise. The difficulty in the management of these patients arises from variable degrees of severity of both arrhythmia and heart failure presentation. For example, arrhythmia-based complications in pregnancy can range from isolated premature ventricular contractions to life-threatening arrhythmias such as sustained ventricular tachycardia. HF also has variable manifestations in pregnant patients ranging from mild left ventricular impairment to patients with advanced heart failure with acute decompensated HF. In high-risk patients, a collaboration between the general obstetrics, maternal-fetal medicine, and cardiovascular teams (which may include cardio-obstetrics, electrophysiology, adult congenital, or advanced HF)—physicians, nurses and allied professionals—can provide the multidisciplinary approach necessary to properly risk-stratify these women and provide appropriate management to improve outcomes.

Risk stratification and management of women with cardiomyopathy/heart failure planning pregnancy or presenting during/after pregnancy: a position statement from the Heart Failure Association of the European Society of Cardiology Study Group on Peripartum Cardiomyopathy

This position paper focusses on the pathophysiology, diagnosis and management of women diagnosed with a cardiomyopathy, or at risk of heart failure (HF), who are planning to conceive or present with (de novo or previously unknown) HF during or after pregnancy. This includes the heterogeneous group of heart muscle diseases such as hypertrophic, dilated, arrhythmogenic right ventricular and non-classified cardiomyopathies, left ventricular non-compaction, peripartum cardiomyopathy, Takotsubo syndrome, adult congenital heart disease with HF, and patients with right HF. Also, patients with a history of chemo-/radiotherapy for cancer or haematological malignancies need specific pre-, during and post-pregnancy assessment and counselling. We summarize the current knowledge about pathophysiological mechanisms, including gene mutations, clinical presentation, diagnosis, and medical and device management, as well as risk stratification. Women with a known diagnosis of a cardiomyopathy will often require continuation of drug therapy, which has the potential to exert negative effects on the foetus. This position paper assists in balancing benefits and detrimental effects.

Pregnancy Counseling in a Young Woman With Left Ventricular Non-Compaction

Left ventricular noncompaction (LVNC) is an uncommon form of cardiomyopathy. Its prevalence in adults is 1:5000. In the differential diagnosis of congestive heart failure, it is rarely the etiology. The etiology of LVNC may be genetic or acquired. There are not guidelines regarding pregnancy planning or outcome in women with this disease. In this presentation, we bring the issue of genetics and pregnancy counseling in women with left ventricular noncompaction.

Acute on Chronic Heart Failure Secondary to Left Ventricular Noncompaction

Left ventricular noncompaction (LVNC) is a rare cardiomyopathy characterized by hypertrabeculations and intertrabecular recesses most often seen in the left ventricle (LV). The patient may be asymptomatic or present with heart failure, arrhythmia, and sudden death. We discuss a previously healthy 7-year-old male who presented to the Emergency Department (ED) multiple times over a three-week period. His complaints evolved over the course of his illness, initially presenting with fatigue and suicidal ideation, followed by diffuse abdominal pain. Prior to his ICU admission, he had been discharged from the ED twice, due to well appearance and reassuring lab findings. He returned to the ED a final time with severe venous congestion and cardiogenic shock with acute hepatic injury. Echocardiogram revealed LV apical hypertrabeculation with a severe dilated cardiomyopathy and biventricular failure along with a large thrombus in the left ventricular cavity. Congestive heart failure and anticoagulation therapy was initiated, and the patient went on to biventricular assist device (BiVAD) placement and cardiac transplant. Although LVNC is rare, pediatric heart failure does present to the general pediatrician and has high morbidity and mortality. The presenting symptoms can be obscure and pose a challenge to pediatricians. This case report and review will assist in familiarizing the general pediatrician with pediatric heart failure presentation, treatment, and course.

Left ventricular non-compaction as a potential source for cryptogenic ischemic stroke in the young: A case-control study

Background

Up to 50% of ischemic strokes in the young after thorough diagnostic work-up remain cryptogenic or associated with low-risk sources of cardioembolism such as patent foramen ovale (PFO). We studied with cardiac magnetic resonance (CMR) imaging, whether left ventricular (LV) non-compaction—a possible source for embolic stroke due to sluggish blood flow in deep intertrabecular recesses—is associated with cryptogenic strokes in the young.

Methods

Searching for Explanations for Cryptogenic Stroke in the Young: Revealing the Etiology, Triggers, and Outcome (SECRETO; NCT01934725) is an international prospective multicenter case-control study of young adults (aged 18–49 years) presenting with an imaging-positive first-ever ischemic stroke of undetermined etiology. In this pilot substudy, 30 cases and 30 age- and sex-matched stroke-free controls were examined with CMR. Transcranial Doppler (TCD) bubble test was performed to evaluate the presence and magnitude of right-to-left shunt (RLS).

Results

There were no significant differences in LV volumes, masses or systolic function between cases and controls; none of the participants had non-compaction cardiomyopathy. Semi-automated assessment of LV non-compaction was highly reproducible. Non-compacted LV mass (median 14.0 [interquartile range 12.6–16.0] g/m² vs. 12.7 [10.4–16.6] g/m², p = 0.045), the ratio of non-compacted to compacted LV mass (mean 25.6 ± 4.2% vs. 22.8 ± 6.0%, p = 0.015) and the percentage of non-compacted LV volume (mean 17.6 ± 2.9% vs. 15.7 ± 3.8%, p = 0.004) were higher in cases compared to controls. In a multivariate conditional logistic regression model including non-compacted LV volume, RLS and body mass index, the percentage of non-compacted LV volume (odds ratio [OR] 1.55, 95% confidence interval [CI] 1.10–2.18, p = 0.011) and the presence of RLS (OR 11.94, 95% CI 1.14–124.94, p = 0.038) were independently associated with cryptogenic ischemic stroke.

Conclusions

LV non-compaction is associated with a heightened risk of cryptogenic ischemic stroke in young adults, independent of concomitant RLS and in the absence of cardiomyopathy.

Clinical trial registration

SECRETO; NCT01934725. Registered 4^th September 2013. https://clinicaltrials.gov/ct2/show/NCT01934725

[Left ventricular non - compaction: contemporary view of genetic background, clinical course, diagnostic and treatment]

This review highlights and discusses recent advances in understanding left ventricular non - compaction (LVNC). Clinical profile, prognosis and even diagnosis are still a great challenge faced by the world. The population prevalence of left ventricular non - compaction remains unknown. High variability of clinical manifestations, genetic heterogenity with overlap of different phenotypes, variability of hereditary patterns suggests that LVNC seems to be rather an isolated trait or a part of phenotypic expression of different cardiac diseases or complex genetic syndromes.

Cardiomyopathy and pregnancy

Cardiomyopathy is a group of disorders in which the heart muscle is structurally and functionally abnormal in the absence of other diseases that could cause observed myocardial abnormality. The most common cardiomyopathies are hypertrophic and dilated cardiomyopathy. Rare types are arrhythmogenic right ventricular, restrictive, Takotsubo and left ventricular non-compaction cardiomyopathies. This review of cardiomyopathies in pregnancy shows that peripartum cardiomyopathy is the most common cardiomyopathy in pregnancy. Peripartum cardiomyopathy develops most frequently in the month before or after partum, whereas dilated cardiomyopathy often is known already or develops in the second trimester. Mortality in peripartum cardiomyopathy varies from <2% to 50%. Few reports on dilated cardiomyopathy and pregnancy exist, with only a limited number of patients. Ventricular arrhythmias, heart failure, stroke and death are found in 39%-60% of high-risk patients. However, patients with modest left ventricular dysfunction and good functional class tolerated pregnancy well. Previous studies on >700 pregnancies in 500 women with hypertrophic cardiomyopathy showed that prognosis was generally good, even though three deaths were reported in high-risk patients. Complications include different types of supraventricular and ventricular arrhythmias, heart failure and ischaemic stroke. Recent studies on 200 pregnancies in 100 women with arrhythmogenic right ventricular cardiomyopathy have reported symptoms, including heart failure in 18%-33% of pregnancies. Ventricular tachycardia was found in 0%-33% of patients and syncope in one patient. Information on rare cardiomyopathies is sparse and only presented in case reports. Close monitoring by multidisciplinary teams in referral centres that counsel patients before conception and follow them throughout gestation is recommended.

Whole exome sequencing identifies novel candidate mutations in a Chinese family with left ventricular noncompaction

Left ventricular noncompaction (LVNC) is an inherited cardiomyopathy involving numerous genes. To identify novel candidate causal mutations, a whole exome sequencing study was performed on a Chinese LVNC family. Exons of the most prevalent pathogenic genes of LVNC (myosin heavy chain 7 and actin, α‑cardiac muscle 1) were sequenced, although no mutations were identified. Following this, Burrows‑Wheeler Aligner, PICARD and Genome Analysis Toolkit (v.2.8) were used to analyze the exome sequencing data. Non‑silent single nucleotide variants (SNVs) that were identified in patients with LVNC, although not in the healthy individual, were investigated further using SNV prioritization via the integration of genomic data (SPRING) based on P‑values. Co‑expressed gene enrichment analysis was performed using Genotype Tissue Expression (GTEx) data in order to investigate the potential roles of the genes containing SNVs in the myocardium. In the Chinese LVNC family, seven novel SNVs were identified that were only present in patients with LVNC and annotated by SPRING with P<0.05. Among these SNVs, hemicentin 1 [c. thymine (T) 9776 cytosine (C)], tolloid like 2 [c. cytosine (C) 2615 thymine (T)], fms related tyrosine kinase 3 [c. guanine (G) 976 adenine (A)] and nucleotide binding protein like [c. guanine (G) 91 thymine (T)] were located in conserved regions and annotated as deleterious by PolyPhen2, LRT and MutationTaster database analyses. Based on GTEx data, it was revealed that NUBPL was co‑expressed with almost all previously established LVNC pathogenic genes. Furthermore, the results of the present study demonstrated that genes co‑expressed with NUBPL were additionally enriched in the Notch signaling pathway. In addition, the results revealed numerous novel mutations that may be causal SNVs for the development of LVNC in the family involved in the present study.

Non-compaction of left ventricular myocardium in sub-Saharan African adults

BACKGROUND

Non-compaction of the left ventricle (NCLV) is an unclassified cardiomyopathy due to intrauterine arrest of compaction of the loose interwoven meshwork. Only a few studies involving sub-Saharan Africans insmall numbers have been published. The aim of our study was to determine the diagnostic, therapeutic and prognostic aspects as well as the clinical course of NCLV in a black African population.

METHODOLOGY

A multicentre retrospective study was carried out between November 2007 and June 2012 in two cardiology departments in Dakar. Patients who met the echocardiographic criteria for NCLV were included in the study.

RESULTS

35patients with the diagnosis of NCLV were evaluated in the study. Their mean age was 47±18.4 years. Heart failure was found in 77.1% of the patients. The most frequent electrocardiographic abnormalities were left ventricular hypertrophy (LVH) (46%) and sinus tachycardia (43%). Mean non-compaction/compaction ratio was 2.84±0.68 with preferential localization in the apex of the left ventricle. The main complications observed were cardiogenic shock (23.5%), pulmonary embolism (6.3%) and ventricular tachycardia (5.9%). Diuretics and ACE inhibitors were the medications most often prescribed. Age >60 years (p=0.04), male gender (p=0.03) and the occurrence of complications during follow-up (p=0.04) were noted to be predictors of poor prognosis.

CONCLUSION

Contrary to previous beliefs, NCLV may not be less common in black Africans than in other ethnic subgroups. Clinicians in Africa should be made aware of NCLV so that it can be diagnosed at earlier stages.

Left Ventricular Noncompaction Cardiomyopathy in Pediatric Patients: A Case Series of a Clinically Heterogeneous Disease

Left ventricular noncompaction is a rare form of cardiomyopathy, which results from multiple trabeculations in the left ventricular myocardium. The clinical presentation is highly variable, and spectrum includes asymptomatic patients diagnosed during family screening on one end to patients with depressed systolic function, heart failure, thromboembolic complications, and cardiac arrhythmias on the other (Kim et al in J Am Coll Cardiol 53: 2009, 2009). Further, the progression of the condition is highly variable. Hence, these patients require close follow-up, and management for each patient needs to be individualized and periodically reevaluated. Here, we present a series of five cases that have been followed in our practice and present our experience. A literature review of this rare form of congenital cardiomyopathy is also presented.

The pathogenicity of genetic variants previously associated with left ventricular non-compaction

Background

Left ventricular non‐compaction (LVNC) is a rare cardiomyopathy. Many genetic variants have been associated with LVNC. However, the number of the previous LVNC‐associated variants that are common in the background population remains unknown. The aim of this study was to provide an updated list of previously reported LVNC‐associated variants with biologic description and investigate the prevalence of LVNC variants in healthy general population to find false‐positive LVNC‐associated variants.

Methods and Results

The Human Gene Mutation Database and PubMed were systematically searched to identify all previously reported LVNC‐associated variants. Thereafter, the Exome Sequencing Project (ESP) and the Exome Aggregation Consortium (ExAC), that both represent the background population, was searched for all variants. Four in silico prediction tools were assessed to determine the functional effects of these variants. The prediction results of those identified in the ESP and ExAC and those not identified in the ESP and ExAC were compared. In 12 genes, 60 LVNC‐associated missense/nonsense variants were identified. MYH7 was the predominant gene, encompassing 24 of the 60 LVNC‐associated variants. The ESP only harbored nine and ExAC harbored 18 of the 60 LVNC‐associated variants. In total, eight out of nine ESP‐positive variants overlapped with the 18 variants identified in ExAC database.

Conclusions

In this article, we identified 9 ESP‐positive and 18 ExAC‐positive variants of 60 previously reported LVNC‐associated variants, suggesting that these variants are not necessarily the monogenic cause of LVNC.

Sequential Notch activation regulates ventricular chamber development

Ventricular chambers are essential for the rhythmic contraction and relaxation occurring in every heartbeat throughout life. Congenital abnormalities in ventricular chamber formation cause severe human heart defects. How the early trabecular meshwork of myocardial fibres forms and subsequently develops into mature chambers is poorly understood. We show that Notch signalling first connects chamber endocardium and myocardium to sustain trabeculation, and later coordinates ventricular patterning and compaction with coronary vessel development to generate the mature chamber, through a temporal sequence of ligand signalling determined by the glycosyltransferase manic fringe (MFng). Early endocardial expression of MFng promotes Dll4-Notch1 signalling, which induces trabeculation in the developing ventricle. Ventricular maturation and compaction require MFng and Dll4 downregulation in the endocardium, which allows myocardial Jag1 and Jag2 signalling to Notch1 in this tissue. Perturbation of this signalling equilibrium severely disrupts heart chamber formation. Our results open a new research avenue into the pathogenesis of cardiomyopathies.

Endocardial Notch Signaling in Cardiac Development and Disease

The Notch signaling pathway is an ancient and highly conserved signaling pathway that controls cell fate specification and tissue patterning in the embryo and in the adult. Region-specific endocardial Notch activity regulates heart morphogenesis through the interaction with multiple myocardial-, epicardial-, and neural crest-derived signals. Mutations in NOTCH signaling elements cause congenital heart disease in humans and mice, demonstrating its essential role in cardiac development. Studies in model systems have provided mechanistic understanding of Notch function in cardiac development, congenital heart disease, and heart regeneration. Notch patterns the embryonic endocardium into prospective territories for valve and chamber formation, and later regulates the signaling processes leading to outflow tract and valve morphogenesis and ventricular trabeculae compaction. Alterations in NOTCH signaling in the endocardium result in congenital structural malformations that can lead to disease in the neonate and adult heart.

Cardiomyopathy Phenotypes and Outcomes for Children With Left Ventricular Myocardial Noncompaction: Results From the Pediatric Cardiomyopathy Registry

BACKGROUND

Left ventricular noncompaction (LVNC) is a distinct form of cardiomyopathy characterized by hypertrabeculation of the left ventricle. The LVNC phenotype may occur in isolation or with other cardiomyopathy phenotypes. Prognosis is incompletely characterized in children.

METHODS AND RESULTS

According to diagnoses from the National Heart, Lung, and Blood Institute-funded Pediatric Cardiomyopathy Registry from 1990 to 2008, 155 of 3,219 children (4.8%) had LVNC. Each LVNC patient was also classified as having an associated echocardiographically diagnosed cardiomyopathy phenotype: dilated (DCM), hypertrophic (HCM), restrictive (RCM), isolated, or indeterminate. The time to death or transplantation differed among the phenotypic groups (P = .035). Time to listing for cardiac transplantation significantly differed by phenotype (P < .001), as did time to transplantation (P = .015). The hazard ratio for death/transplantation (with isolated LVNC as the reference group) was 4.26 (95% confidence interval [CI] 0.78-23.3) for HCM, 6.35 (95% CI 1.52-26.6) for DCM, and 5.66 (95% CI 1.04-30.9) for the indeterminate phenotype. Most events occurred in the 1st year after diagnosis.

CONCLUSIONS

LVNC is present in at least 5% of children with cardiomyopathy. The specific LVNC-associated cardiomyopathy phenotype predicts the risk of death or transplantation and should inform clinical management.

The hypertrabeculated (noncompacted) left ventricle is different from the ventricle of embryos and ectothermic vertebrates

Ventricular hypertrabeculation (noncompaction) is a poorly characterized condition associated with heart failure. The condition is widely assumed to be the retention of the trabeculated ventricular design of the embryo and ectothermic (cold-blooded) vertebrates. This assumption appears simplistic and counterfactual. Here, we measured a set of anatomical parameters in hypertrabeculation in man and in the ventricles of embryos and animals. We compared humans with left ventricular hypertrabeculation (N=21) with humans with structurally normal left ventricles (N=54). We measured ejection fraction and ventricular trabeculation using cardiovascular MRI. Ventricular trabeculation was further measured in series of embryonic human and 9 animal species, and in hearts of 15 adult animal species using MRI, CT, or histology. In human, hypertrabeculated left ventricles were significantly different from structurally normal left ventricles by all structural measures and ejection fraction. They were far less trabeculated than human embryonic hearts (15-40% trabeculated volume versus 55-80%). Early in development all vertebrate embryos acquired a ventricle with approximately 80% trabeculations, but only ectotherms retained the 80% trabeculation throughout development. Endothermic (warm-blooded) animals including human slowly matured in fetal and postnatal stages towards ventricles with little trabeculations, generally less than 30%. Further, the trabeculations of all embryos and adult ectotherms were very thin, less than 50 μm wide, whereas the trabeculations in adult endotherms and in the setting of hypertrabeculation were wider by orders of magnitude. It is concluded in contrast to a prevailing assumption, the hypertrabeculated left ventricle is not like the ventricle of the embryo or of adult ectotherms. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

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.

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.

Loss of Function Mutations in NNT Are Associated With Left Ventricular Noncompaction

BACKGROUND

Left ventricular noncompaction (LVNC) is an autosomal-dominant, genetically heterogeneous cardiomyopathy with variable severity, which may co-occur with cardiac hypertrophy.

METHODS AND RESULTS

Here, we generated whole exome sequence data from multiple members from 5 families with LVNC. In 4 of 5 families, the candidate causative mutation segregates with disease in known LVNC genes MYH7 and TPM1. Subsequent sequencing of MYH7 in a larger LVNC cohort identified 7 novel likely disease causing variants. In the fifth family, we identified a frameshift mutation in NNT, a nuclear-encoded mitochondrial protein, not implicated previously in human cardiomyopathies. Resequencing of NNT in additional LVNC families identified a second likely pathogenic missense allele. Suppression of nnt in zebrafish caused early ventricular malformation and contractility defects, probably driven by altered cardiomyocyte proliferation. In vivo complementation studies showed that mutant human NNT failed to rescue nnt morpholino-induced heart dysfunction, indicating a probable haploinsufficiency mechanism.

CONCLUSIONS

Together, our data expand the genetic spectrum of LVNC and demonstrate how the intersection of whole exome sequence with in vivo functional studies can accelerate the identification of genes that drive human genetic disorders.

Neuromuscular comorbidity, heart failure, and atrial fibrillation as prognostic factors in left ventricular hypertrabeculation/noncompaction

BACKGROUND

There is some controversy concerning the prognosis of patients with left ventricular hypertrabeculation/noncompaction (LVHT). LVHT is frequently associated with neuromuscular disorders (NMDs). The aim of this study was to assess cardiac and neurological findings as predictors of mortality in patients with LVHT.

PATIENTS AND METHODS

The study included patients with LVHT diagnosed between June 1995 and January 2014 in one echocardiographic laboratory. They underwent a baseline cardiologic examination and were invited for a neurological examination. Between January and February 2014, their survival status was assessed.

RESULTS

LVHT was diagnosed in 220 patients (68 female, aged 52 ± 17 years) with a prevalence of 0.35 %/year. During a follow-up of 72 ± 61 months, 65 patients died. The mortality was 5 %/year. A neurological investigation was performed on 173 patients (79 %) and revealed specific NMDs in 31 (14 %), NMD of unknown etiology in 103 (47 %), and normal findings in 39 (18 %) patients. In multivariate analysis, the predictors of mortality were increased age (p = 0.0001), presence of a specific NMD (p = 0.0062) or NMD of unknown etiology (p = 0.0062), heart failure NYHA III (p = 0.0396), atrial fibrillation (p = 0.0022), and sinus tachycardia (p = 0.0395).

CONCLUSIONS

LVHT patients should undergo systematic neurological examinations. Whether an optimal therapy of heart failure and atrial fibrillation will improve the prognosis of LVHT patients needs to be addressed in further studies.

Age-dependency of cardiac and neuromuscular findings in adults with left ventricular hypertrabeculation/noncompaction

Left ventricular hypertrabeculation/noncompaction (LVHT) is diagnosed in all ages and is frequently associated with neuromuscular disorders (NMDs). The aim of the study was to compare patients with LVHT depending on age at diagnosis. Included were 232 patients with LVHT (72 women, mean age 52±17 years) diagnosed from 1995 to 2014 at 1 echocardiographic laboratory. In 2014, their survival was assessed. Seventy-six percent of the patients were neurologically investigated, revealing specific NMDs in 18%, unspecific NMDs in 60%, and normal findings in 22%. Forty-five patients (19%) received electronic devices: implantable cardioverter-defibrillators in 26 patients, combined with cardiac resynchronization systems (n=14) or an antibradycardic pacemaker (n=1); antibradycardic pacemakers (n=8); cardiac resynchronization systems (n=4); implantable loop recorders (n=4); life vests (n=2); and a left ventricular assist device as a bridge to transplantation (n=1). During 72-month follow-up, mortality was 4.9% per year. In younger age groups, more patients were referred for syncope or palpitations, whereas in older age groups, more patients were referred for heart failure. Classic cardiovascular risk factors such as hypertension and diabetes, as well as coronary artery stenosis, were rare in the young age groups but were more prevalent in older age groups. Differences between age groups were found regarding cardiac symptoms, NMDs, electrocardiographic findings, rate of device implantation, and mortality but not in location and extension of LVHT. None of the neurologically investigated patients≥70 years of age was neurologically normal. Prevalence of heart failure, electrocardiographic abnormalities, and mortality were highest in the oldest age group. In conclusion, LVHT must be considered as an echocardiographic diagnosis in all age groups. The morphologic pattern of LVHT is similar, whereas clinical manifestations and prognosis are variable among age groups.

Basic Study and Clinical Implications of Left Ventricular False Tendon. Is it Associated With Innocent Murmur in Children or Heart Disease?

INTRODUCTION AND OBJECTIVES

Left ventricular false tendon is a structure of unknown function in cardiac physiology that was first described anatomically by Turner. This condition may be related to various electrical or functional abnormalities, but no consensus has ever been reached. The purpose of this study was to determine the time of appearance, prevalence and histologic composition of false tendon, as well as its association with innocent murmur in children and with heart disease.

METHODS

The basic research was performed by anatomic dissection of hearts from adult human cadavers to describe false tendon and its histology. The clinical research consisted of echocardiographic study in a pediatric population to identify any relationship with heart disease, innocent murmur in children, or other abnormalities. Fetal echocardiography was performed prenatally at different gestational ages.

RESULTS

False tendon was a normal finding in cardiac dissection and was composed of muscle and connective tissue fibers. In the pediatric population, false tendon was present in 83% on echocardiography and showed a statistically significant association only with innocent murmur in children and slower aortic acceleration. The presence of false tendon was first observed on fetal echocardiography from week 20 of pregnancy.

CONCLUSIONS

Left ventricular false tendon is a normal finding visualized by fetal echocardiography from week 20 and is present until adulthood with no pathologic effects except for innocent murmur during childhood. It remains to be determined if false tendon is the cause of the murmurs or if its absence or structural anomalies are related to disease.

Sudden death due to biventricular non-compaction cardiomyopathy in a 14-year-old

A 14-year-old African-American female with a long-standing medically and ablation-treated history of tachycardia with associated seizures died suddenly. Upon autopsy, evidence of gross non-compaction involving the left ventricle, as well as possible subtle non-compaction of the right ventricle was discovered. Microscopically, there was focal myocyte hypertrophy as well as myxoid connective tissue and subendocardial fibroelastosis in the areas affected by the non-compaction. Arrhythmia, precipitated by the underlying cardiomyopathy, led to this young girl's death. Non-compaction cardiomyopathy is a rare cardiac disorder which commonly goes undiagnosed until post-mortem, although diagnosis through echocardiogram, CT, or MRI is possible and there is criterion for diagnosis with each of these.

Effects of cardiac resynchronization therapy on left ventricular remodeling and dyssynchrony in patients with left ventricular noncompaction and heart failure

Left ventricular noncompaction (LVNC) is a rare cardiomyopathy with high incidence of heart failure (HF). It is unclear whether LVNC patients with desynchronized HF would benefit from cardiac resynchronization therapy (CRT). In order to evaluate the effect of CRT on LVNC, this study explored left ventricular (LV) remodeling and mechanical synchronicity before and after CRT in LVNC patients, and compare with that in idiopathic dilated cardiomyopathy (DCM) patients. We collected 15 LVNC and 30 matched DCM patients. All the patients underwent clinical evaluation,electrocardiogram and echocardiography before CRT and ≥6 months later. LV response was defined as ≥15 % decrease in LV end-systolic volume (LVESV). Longitudinal synchronicity was quantified by YU-index using tissue Doppler imaging. The time delay of peak radial strain from anteroseptal to posterior wall, which derived from speckle tracking imaging, was used to quantify radial synchronicity. In LVNC group, LV ejection fraction increased from 27.6 ± 5.5 to 39.1 ± 7.0 % (P < 0.01) during follow-up, but LV volumes did not change significantly (both P > 0.05). Five LVNC patients (33.3 %) responded to CRT, and all of them were super-responders (reduction in LVESV > 30 %). In addition, the number of noncompacted segments and the thickness ratio of noncompacted to compacted myocardium decreased (both P < 0.05). Inter-ventricular, longitudinal and radial intra-ventricular dyssynchrony also reduced significantly (all P < 0.05). Compared with DCM group, there was no significant difference in LV response rate (33.3 vs. 60.0 %, P = 0.092), improvement of LV function and dyssynchrony index (all P < 0.05). In conclusion, CRT improved heart function, morphology and mechanical dyssynchrony in LVNC patients.

Severe heart failure due to noncompaction cardiomyopathy: a case report

Noncompaction cardiomyopathy involves an infrequent pathology whose diagnosis has been rising in recent years owing to a better understanding of the disease and, therefore, better diagnosis. Today, there are no well established protocols for its treatment. For this reason, it is necessary to adapt the therapy of choice to each patient. We report the case of a 35-year-old man with no past medical history of interest who was admitted due to acute pulmonary edema. Diagnostic tests revealed noncompaction cardiomyopathy with biventricular severe systolic dysfunction. In this situation, heart transplantation was considered to be the best therapeutic option, which was carried out with an uneventful postoperative course. This is one of the few cases reported in the literature for this issue.

Isolated right ventricular noncompaction in a newborn

Noncompaction of the ventricular myocardium is a rare cardiomyopathy characterized by a pattern of prominent trabecular meshwork and deep intertrabecular recesses. The prevalence of left ventricular noncompaction is 0.01% in adults and 0.14% in pediatric patients. Although the usual site of involvement is the left ventricle, the right ventricle and septum can be affected as well. Previously, right ventricular noncompaction has been described only in a few cases of newborns with congenital heart defects and in adult patients. This report presents a newborn with isolated right ventricular noncompaction. To the authors' knowledge, this is the first newborn patient with isolated right ventricular noncompaction but no congenital heart defect involving only the right ventricle.

Echocardiography in the diagnosis of apical non-compaction associated with congenital heart diseases

BACKGROUND

Isolated left ventricular non-compaction has been reported extensively. However, apical non-compaction of both ventricles and the interventricular septum (IVS) is not often reported in the literature. The objective of our study is to evolve the echocardiographic diagnostic criteria and to assess the types and impact of the associated lesions in "apical non-compaction".

METHODS AND RESULTS

Seventy consecutive cases that fulfilled standard echocardiographic criteria for non-compaction of the left ventricle and, in addition, N/C ratio of >3 for the right ventricle and apical IVS formed the material. The age of patients ranged from 3 days to 35 years, with 37 males and 33 females. The associated lesions were present in all 70 cases: 62 had acyanotic (88.6 %) and 8 had cyanotic congenital heart diseases (11.4 %). Of the 70 cases, 18 had pump failure (25.7 %): 8 cases had left ventricular dysfunction, 7 had right ventricular dysfunction, and 3 had biventricular dysfunction; 33 (47.1 %) had pulmonary hypertension, 2 (2.9 %) had thrombus, and 1 (1.4 %) had tachyarrhythmia. Pump failure was worsened by volume overload in 33.9 % and by pressure overload in 8.1 % of cases. Some very rare lesions were detected. All 70 cases had Swiss cheese appearance of the apical half of the IVS, looking like the delta of a river.

CONCLUSION

All of the apical non-compaction syndrome cases had associated lesions, mostly acyanotic congenital heart disease with volume overload, rather than obstructive lesions. Transthoracic echocardiography plays an important role in the diagnosis of apical non-compaction syndrome and associated lesions that worsen the pump failure.

Pregnancy, cardiomyopathies, and genetics

Although familial forms of cardiomyopathy such as hypertrophic or dilated cardiomyopathy have been recognized for decades, it is only recently that much of the genetic basis of these inherited cardiomyopathies has been elucidated. This has provided important insights into the pathophysiological mechanisms underlying the disease phenotype. This increased knowledge and the availability of genetic testing has resulted in increasing numbers of mutation carriers who are being monitored, including many who are now of child-bearing age. Pregnancy is generally well tolerated in asymptomatic patients or mutation carriers with inherited cardiomyopathies. However, since pregnancy leads to major physiological changes in the cardiovascular system, in women with genetic cardiomyopathies or who carry a mutation pre-disposing to a genetic cardiomyopathy, pregnancy entails a risk of developing heart failure and/or arrhythmias. This deterioration of cardiac function may occur despite optimal medical treatment. Advanced left ventricular dysfunction, poor functional class (NYHA class III or IV), or prior cardiac events appear to increase the risk of maternal cardiac complications. However, there are no large series of cardiomyopathy patients who are regularly evaluated for cardiac complications during pregnancy and for certain types of inherited cardiomyopathy, only case reports on individual pregnancies are available. Pre-conception cardiologic evaluation and genetic counselling are important for every woman with a cardiomyopathy or a cardiomyopathy-related mutation who is considering having a family. In this article, we give an overview of the basic clinical aspects, genetics, and pregnancy outcome in women with different types of inherited cardiomyopathies. We also discuss the genetic aspects of pregnancy-associated cardiomyopathy, including peripartum cardiomyopathy.

Focal left atrial tachycardia in a patient with left ventricular noncompaction

Left ventricular noncompaction (LVNC) is a rare disease caused by intrauterine failure of the myocardium to compact. The major clinical manifestations of LVNC include heart failure, ventricular tachyarrhythmia, thromboembolic event, and sudden deaths. Atrial arrhythmia usually seen is atrial fibrillation. We report a rare case of focal left atrial tachycardia in an 18-year-old patient who presented for evaluation of persistent tachycardia. Transthoracic echocardiogram showed severe systolic dysfunction and evidence of noncompaction of the left ventricle. A detailed review of ECG revealed the possibility of ectopic atrial tachycardia, most likely originating from the left side. Electrophysiology study showed sustained atrial tachycardia originating on the ridge anterior to the left sided pulmonary veins. A successful radiofrequency catheter ablation was performed at this site without any complications.

A study of tropomyosin's role in cardiac function and disease using thin-filament reconstituted myocardium

Tropomyosin (Tm) is the key regulatory component of the thin-filament and plays a central role in the cardiac muscle's cooperative activation mechanism. Many mutations of cardiac Tm are related to hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and left ventricular noncompaction (LVNC). Using the thin-filament extraction/reconstitution technique, we are able to incorporate various Tm mutants and protein isoforms into a muscle fiber environment to study their roles in Ca(2+) regulation, cross-bridge kinetics, and force generation. The thin-filament reconstitution technique poses several advantages compared to other in vitro and in vivo methods: (1) Tm mutants and isoforms are placed into the real muscle fiber environment to exhibit their effect on a level much higher than simple protein complexes; (2) only the primary and immediate effects of Tm mutants are studied in the thin-filament reconstituted myocardium; (3) lethal mutants of Tm can be studied without causing a problem; and (4) inexpensive. In transgenic models, various secondary effects (myocyte disarray, ECM fibrosis, altered protein phosphorylation levels, etc.) also affect the performance of the myocardium, making it very difficult to isolate the primary effect of the mutation. Our studies on Tm have demonstrated that: (1) Tm positively enhances the hydrophobic interaction between actin and myosin in the "closed state", which in turn enhances the isometric tension; (2) Tm's seven periodical repeats carry distinct functions, with the 3rd period being essential for the tension enhancement; (3) Tm mutants lead to HCM by impairing the relaxation on one hand, and lead to DCM by over inhibition of the AM interaction on the other hand. Ca(2+) sensitivity is affected by inorganic phosphate, ionic strength, and phosphorylation of constituent proteins; hence it may not be the primary cause of the pathogenesis. Here, we review our current knowledge regarding Tm's effect on the actomyosin interaction and the early molecular pathogenesis of Tm mutation related to HCM, DCM, and LVNC.

Quantification of left ventricular trabeculae using fractal analysis

BACKGROUND

Left ventricular noncompaction (LVNC) is a myocardial disorder characterized by excessive left ventricular (LV) trabeculae. Current methods for quantification of LV trabeculae have limitations. The aim of this study is to describe a novel technique for quantifying LV trabeculation using cardiovascular magnetic resonance (CMR) and fractal geometry. Observing that trabeculae appear complex and irregular, we hypothesize that measuring the fractal dimension (FD) of the endocardial border provides a quantitative parameter that can be used to distinguish normal from abnormal trabecular patterns.

METHODS

Fractal analysis is a method of quantifying complex geometric patterns in biological structures. The resulting FD is a unitless measure index of how completely the object fills space. FD increases with increased structural complexity. LV FD was measured using a box-counting method on CMR short-axis cine stacks. Three groups were studied: LVNC (defined by Jenni criteria), n=30(age 41±13; men, 16); healthy whites, n=75(age, 46±16; men, 36); healthy blacks, n=30(age, 40±11; men, 15).

RESULTS

In healthy volunteers FD varied in a characteristic pattern from base to apex along the LV. This pattern was altered in LVNC where apical FD were abnormally elevated. In healthy volunteers, blacks had higher FD than whites in the apical third of the LV (maximal apical FD: 1.253±0.005 vs. 1.235±0.004, p<0.01) (mean±s.e.m.). Comparing LVNC with healthy volunteers, maximal apical FD was higher in LVNC (1.392±0.010, p<0.00001). The fractal method was more accurate and reproducible (ICC, 0.97 and 0.96 for intra and inter-observer readings) than two other CMR criteria for LVNC (Petersen and Jacquier).

CONCLUSIONS

FD is higher in LVNC patients compared to healthy volunteers and is higher in healthy blacks than in whites. Fractal analysis provides a quantitative measure of trabeculation and has high reproducibility and accuracy for LVNC diagnosis when compared to current CMR criteria.