Left ventricular non-compaction and its cardiac and neurologic implications

Advances in symptomatic therapy for left ventricular non-compaction in children

Left ventricular non-compaction is a complex cardiomyopathy and the third largest childhood cardiomyopathy, for which limited knowledge is available. Both pathogenesis and prognosis are still under investigation. Currently, no effective treatment strategy exists to reduce its incidence or severity, and symptomatic treatment is the only clinical treatment strategy. Treatment strategies are constantly explored in clinical practice, and some progress has been made in coping with the corresponding symptoms because the prognosis of children with left ventricular non-compaction is usually poor if there are complications. In this review, we summarized and discussed the coping methods for different left ventricular non-compaction symptoms.

Left Ventricular Non-Compaction Cardiomyopathy - Left ventricular dilation and dysfunction at baseline portend the risk of death or heart transplantation

BACKGROUND

Left ventricular non-compaction (LVNC) is associated with genetic and phenotypic variability that influences outcomes. We aimed to identify risk factors for death or heart transplant (HTX) in a paediatric LVNC cohort.

METHODS

We reviewed patients < 18 years of age (2001 - 2018) with LVNC, either isolated (I-LVNC) or with dilated phenotype (D-LVNC) and at least mildly reduced ejection fraction (EF). Patients with dilated cardiomyopathy (DCM) were included as controls. Descriptive statistics, multivariate analysis, and time-to-event analysis were used.

RESULTS

We included 188 patients, 34 (18%) with I-LVNC, 37 (20%) with D-LVNC, and 117 (62%) with DCM. Overall median age at diagnosis = 1.08 years (IQR = 0.22 - 10.65) and median follow-up = 1.4 (IQR = 0.2 - 5.2) years. I-LVNC patients' median baseline LV ejection fraction (LVEF) was 47%, compared with D-LVNC 33%, and DCM 21% (p<0.0001). 62% of I-LVNC patients developed moderate to severe LV dysfunction during follow-up. The incidence of death or transplantation was 43.6% in the overall cohort. Freedom from death or transplantation at 10 years after diagnosis was 88.6% (95% CI, 76-100) for I-LVNC, 47% (95% CI, 29-65) for D-LVNC and 42.3% (95% CI, 33-52) for DCM. On multivariable analysis, baseline LVEF and LVEDD z-score were associated with death or transplantation. Patients with a baseline LVEDD z-score > 4 and moderate to severe LV dysfunction had a transplant free survival of 38%.

CONCLUSIONS

Baseline LV dilation and systolic dysfunction were independently associated with progression to death or HTX in LVNC patients.

Myocardium-Specific Deletion of Rac1 Causes Ventricular Noncompaction and Outflow Tract Defects

Background: Left ventricular noncompaction (LVNC) is a cardiomyopathy that can lead to arrhythmias, embolic events and heart failure. Despite our current knowledge of cardiac development, the mechanisms underlying noncompaction of the ventricular myocardium are still poorly understood. The small GTPase Rac1 acts as a crucial regulator of numerous developmental events. The present study aimed to investigate the cardiomyocyte specific role of Rac1 in embryonic heart development. Methods and Results: The Nkx2.5-Cre transgenic mice were crossed with Rac1^f/f mice to generate mice with a cardiomyocyte specific deletion of Rac1 (Rac1^Nkx2.5) during heart development. Embryonic Rac1^Nkx2.5 hearts at E12.5–E18.5 were collected for histological analysis. Overall, Rac1^Nkx2.5 hearts displayed a bifid apex, along with hypertrabeculation and a thin compact myocardium. Rac1^Nkx2.5 hearts also exhibited ventricular septal defects (VSDs) and double outlet right ventricle (DORV) or overriding aorta. Cardiomyocytes had a rounded morphology and were highly disorganized, and the myocardial expression of Scrib, a planar cell polarity protein, was reduced in Rac1^Nkx2.5 hearts. In addition, cell proliferation rate was significantly decreased in the Rac1^Nkx2.5 ventricular myocardium at E9.5. Conclusions: Rac1 deficiency in the myocardium impairs cardiomyocyte elongation and organization, and proliferative growth of the heart. A spectrum of CHDs arises in Rac1^Nkx2.5 hearts, implicating Rac1 signaling in the ventricular myocardium as a crucial regulator of OFT alignment, along with compact myocardium growth and development.

Intraventricular synchronism assessment by gated-SPECT myocardial perfusion imaging in cardiac resynchronization therapy. Does cardiomyopathy type influence results?

Purpose

To analyze the evolution post-cardiac resynchronization therapy (CRT) in left ventricular non-compaction (LVNC) cardiomyopathy (CM) patients compared to other types of CM, according to clinical and functional variables, by using gated-SPECT myocardial perfusion imaging (MPI).

Methods

Ninety-three patients (60 ± 11 years, 28% women) referred for pre-CRT assessment were studied and divided into three groups: 1 (non-ischemic CM with LVNC, 11 patients), 2 (ischemic CM, 28 patients), and 3 (non-ischemic CM, 53 patients). All were studied by a ^99mTc-MIBI gated-SPECT MPI at rest pre-CRT implantation and 6 ± 1 months after, including intraventricular dyssynchrony assessment by phase analysis. Quality of life was measured by the Minnesota Living with Heart Failure Questionnaire (MLHFQ).

Results

No differences in sex, atherosclerotic risk factors other than smoking habit, and MLHFQ results were found among groups. LVNC CM patients were younger, with greater QRS width and lower left ventricular ejection fraction (LVEF) at baseline, but the differences were not significant. No significant differences were found at baseline regarding ventricular function, although end-systolic volume was slightly higher in LVNC CM patients. Mean SRS was significantly higher (p < 0.0001) in ischemic patients (14.9) versus non-ischemic ones (8.7 in group 1 and 9 in group 2). At baseline, LVNC CM patients were significantly more dyssynchronous: Their phase standard deviation (PSD) was higher (89.5° ± 14.2°) versus groups 2 (65.2° ± 23.3°) and 3 (69.7° ± 21.7°), p = 0.007. Although the quality of life significantly improved in all groups, non-ischemic patients (with or without LVNC) showed a higher LVEF increase and volumes reduction at 6 months post-CRT. Dyssynchrony reduced post-CRT in all groups. Nevertheless, those more dyssynchronous at baseline (LVNC CM) exhibited the most significant intraventricular synchronism improvement: PSD was reduced from 89.5° ± 14.2° at baseline to 63.7° ± 20.5° post-CRT (p = 0.028). Six months post-CRT, 89% of patients were responders: 11 (100%) of those with LVNC CM, 25 (86%) of those with ischemic CM, and 47 (89%) of patients with non-ischemic CM. No patient with LVNC CM had adverse events during the follow-up.

Conclusion

CRT contributes to a marked improvement in non-ischemic CM patients with non-compaction myocardium. Phase analysis in gated-SPECT MPI is a valuable tool to assess the response to CRT.

NT-pro-BNP in patients with left ventricular hypertrabeculation/non-compaction

Aims

Left ventricular hypertrabeculation/non‐compaction (LVHT) is a cardiac abnormality of unknown pathogenesis and frequently associated with neuromuscular disorders. The N‐terminal fragment of the pro brain natriuretic peptide (NT‐pro‐BNP) is a prognostic marker in heart failure whose relevance in LVHT patients is largely unknown. The aim of the study was to assess the role of NT‐pro‐BNP levels as prognostic markers in LVHT.

Methods and results

Data of LVHT patients were collected in a database from one echocardiographic laboratory since 1996. The hospital information system was screened for measurements of NT‐pro‐BNP levels, and their association with clinical and echocardiographic baseline parameters was retrospectively assessed. During follow‐up, the endpoints were death and heart transplantation. In 113 patients (median age 57 years, 24% women), data about NT‐pro‐BNP measurements were found, ranging from 8 to 121 152 (median 2029) ng/L. High NT‐pro‐BNP levels were associated with heart failure, valvular abnormalities, diabetes mellitus, hypertension, angina pectoris, number of LVHT‐affected segments, end‐diastolic diameter, and systolic dysfunction. During a follow‐up of 73 (±64; 0–237) months, 35% of the patients reached an endpoint. High NT‐pro‐BNP levels were associated with the occurrence of an endpoint (P < 0.001). By multivariate analysis, predictors for endpoints were increased age (P = 0.0025), atrial fibrillation (P = 0.0023), natural logarithm of NT‐pro‐BNP levels (P = 0.0073), diabetes mellitus (P = 0.014), and thromboembolic events before diagnosis (P = 0.0347).

Conclusions

Also in LVHT patients, high NT‐pro‐BNP levels are indicators for death and heart transplantation.

Cardiac Phenotypes in Hereditary Muscle Disorders: JACC State-of-the-Art Review

Hereditary muscular diseases commonly involve the heart. Cardiac manifestations encompass a spectrum of phenotypes, including both cardiomyopathies and rhythm disorders. Common biomarkers suggesting cardiomuscular diseases include increased circulating creatine kinase and/or lactic acid levels or disease-specific metabolic indicators. Cardiac and extra-cardiac traits, imaging tests, family studies, and genetic testing provide precise diagnoses. Cardiac phenotypes are mainly dilated and hypokinetic in dystrophinopathies, Emery-Dreifuss muscular dystrophies, and limb girdle muscular dystrophies; hypertrophic in Friedreich ataxia, mitochondrial diseases, glycogen storage diseases, and fatty acid oxidation disorders; and restrictive in myofibrillar myopathies. Left ventricular noncompaction is variably associated with the different myopathies. Conduction defects and arrhythmias constitute a major phenotype in myotonic dystrophies and skeletal muscle channelopathies. Although the actual cardiac management is rarely based on the cause, the cardiac phenotypes need precise characterization because they are often the only or the predominant manifestations and the prognostic determinants of many hereditary muscle disorders.

Mechanisms of Trabecular Formation and Specification During Cardiogenesis

Trabecular morphogenesis is a key morphologic event during cardiogenesis and contributes to the formation of a competent ventricular wall. Lack of trabeculation results in embryonic lethality. The trabecular morphogenesis is a multistep process that includes, but is not limited to, trabecular initiation, proliferation/growth, specification, and compaction. Although a number of signaling molecules have been implicated in regulating trabeculation, the cellular processes underlying mammalian trabecular formation are not fully understood. Recent works show that the myocardium displays polarity, and oriented cell division (OCD) and directional migration of the cardiomyocytes in the monolayer myocardium are required for trabecular initiation and formation. Furthermore, perpendicular OCD is an extrinsic asymmetric cell division that contributes to trabecular specification, and is a mechanism that causes the trabecular cardiomyocytes to be distinct from the cardiomyocytes in compact zone. Once the coronary vasculature system starts to function in the embryonic heart, the trabeculae will coalesce with the compact zone to thicken the heart wall, and abnormal compaction will lead to left ventricular non-compaction (LVNC) and heart failure. There are many reviews about compaction and LVNC. In this review, we will focus on the roles of myocardial polarity and OCD in trabecular initiation, formation, and specification.

Single-Cell Lineage Tracing Reveals that Oriented Cell Division Contributes to Trabecular Morphogenesis and Regional Specification

The cardiac trabeculae are sheet-like structures extending from the myocardium that function to increase surface area. A lack of trabeculation causes embryonic lethality due to compromised cardiac function. To understand the cellular and molecular mechanisms of trabecular formation, we genetically labeled individual cardiomyocytes prior to trabeculation via the brainbow multicolor system and traced and analyzed the labeled cells during trabeculation by whole-embryo clearing and imaging. The clones derived from labeled single cells displayed four different geometric patterns that are derived from different patterns of oriented cell division (OCD) and migration. Of the four types of clones, the inner, transmural, and mixed clones contributed to trabecular cardiomyocytes. Further studies showed that perpendicular OCD is an extrinsic asymmetric cell division that putatively contributes to trabecular regional specification. Furthermore, N-Cadherin deletion in labeled clones disrupted the clonal patterns. In summary, our data demonstrate that OCD contributes to trabecular morphogenesis and specification.

Noncompaction Cardiomyopathy with Charcot-Marie-Tooth Disease

We report a case of a 53-year-old female presenting with a new-onset heart failure that was contributed secondary to noncompaction cardiomyopathy. The diagnosis was made by echocardiogram and confirmed by cardiac MRI. Noncompaction cardiomyopathy (also known as ventricular hypertrabeculation) is a newly discovered disease. It is considered to be congenital (genetic) cardiomyopathy. It is usually associated with genetic disorders and that could explain the genetic pathogenesis of the non-compaction cardiomyopathy. Our case had a history of Charcot-Marie-Tooth disease. There is a high incidence of arrhythmia and embolic complications. The treatment usually consists of the medical management, defibrillator placement, and lifelong anticoagulation. Heart transplantation will be the last resort.

Health Status and Psychological Distress in Patients with Non-compaction Cardiomyopathy: The Role of Burden Related to Symptoms and Genetic Vulnerability

BACKGROUND

Non-compaction cardiomyopathy (NCCM) is a cardiomyopathy characterized by left ventricular tribeculae and deep intertrabecular recesses. Because of its genetic underpinnings and physical disease burden, noncompaction cardiomyopathy is expected to be associated with a lower health status and increase in pscyhological distress.

PURPOSE

This study determined the health status and psychological distress in NCCM patients. We also examined the potential contribution of genetic predisposition and cardiac symptoms to health status and distress in NCCM, by comparing NCCM patients with (1) patients with familial hypercholesterolemia (FH) and (2) patients with acquired dilated cardiomyopathy (DCM).

METHODS

Patients were recruited from the Erasmus Medical Center, Rotterdam, The Netherlands. Using a case-control design, NCCM patients (N = 45, mean age 46.7 ± 15.1 years, 38 % male) were compared with 43 FH patients and 42 DCM patients. Outcome measures were health status (Short Form Health Survey-12), anxiety (Generalized Anxiety Disorder 7-item scale) and depression (Patient Health Questionnaire 9-item scale).

RESULTS

NCCM patients showed significantly worse health status (Physical Component Score F(1,84) = 9.58, P = .003; Mental Component Score F(1,84) = 16.65, P < .001), anxiety (F(1,85) = 9.63, P = .003) and depression scores (F(1,82) = 5.4, P = .023) compared to FH patients, also after adjusting age, sex, comorbidity, educational level and time since diagnosis. However, NCCM patients did not differ from DCM patients (Physical Component Score F(1,82) = 2,61, P = .11; Mental Component Score F(1,82) = .55, P = .46), anxiety (F(1,82) = 1.16, P = .28) and depression scores (F(1,82) = 1,95, P = .17).

CONCLUSION

Cardiac symptoms are likely to play a role in the observed poor health status and elevated levels of anxiety and depressive symptoms in NCCM, whereas the burden of having a genetic condition may contribute less to these health status and psychological measures.

Thrombotic events in critically ill children with myocarditis

BACKGROUND

Children with myocarditis have multiple risk factors for thrombotic events, yet the role of antithrombotic therapy is unclear in this population. We hypothesised that thrombotic events in critically ill children with myocarditis are common and that children with myocarditis are at higher risk for thrombotic events than children with non-inflammatory dilated cardiomyopathy.

METHODS

This is a retrospective chart review of all children presenting to a single centre cardiac intensive care unit with myocarditis from 1995 to 2008. A comparison group of children with dilated cardiomyopathy was also examined. Antithrombotic regimens were recorded. The primary outcome of thrombotic events included intracardiac clots and any thromboembolic events.

RESULTS

Out of 45 cases with myocarditis, 40% were biopsy-proven, 24% viral polymerase chain reaction-supported, and 36% diagnosed based on high clinical suspicion. There were two (4.4%) thrombotic events in the myocarditis group and three (6.7%) in the dilated cardiomyopathy group (p = 1.0). Neither the use of any antiplatelet or anticoagulation therapy, use of intravenous immune globulin, presence of any arrhythmia, nor need for mechanical circulatory support were predictive of thrombotic events in the myocarditis, dilated cardiomyopathy, or combined groups.

CONCLUSIONS

Thrombotic events in critically ill children with myocarditis and dilated cardiomyopathy occurred in 6% of the combined cohort. There was no difference in thrombotic events between inflammatory and non-inflammatory cardiomyopathy groups, suggesting that the decision to use antithrombotic prophylaxis should be based on factors other than the underlying aetiology of a child's acute decompensated heart failure.

Right ventricular cardiomyopathies: a multidisciplinary approach to diagnosis

The physiological importance of the right ventricle (RV) has been underestimated over the past years. Finally in the early 1950s through the 1970s, cardiac surgeons recognized the importance of RV function. Since then, the importance of RV function has been recognized in many acquired cardiac heart disease. RV can be mainly or together with left ventricle (LV) affected by inherited or acquired cardiomyopathy. In fact, RV morphological and functional remodeling occurs more common during cardiomyopathies than in ischemic cardiomyopathies and more closely parallels LV dysfunction. Moreover, there are some cardiomyopathy subtypes showing a predominant or exclusive involvement of the RV, and they are probably less known by cardiologists. The clinical approach to right ventricular cardiomyopathies is often challenging. Imaging is the first step to raise the suspicion and to guide the diagnostic process. In the differential diagnosis, cardiologists should consider athlete's heart, congenital heart diseases, multisystemic disorders, and inherited arrhythmias. However, a multiparametric and multidisciplinary approach, involving cardiologists, experts in imaging, geneticists, and pathologists with a specific expertise in these heart muscle disorders is required.

Critical roles of miRNA-mediated regulation of TGFβ signalling during mouse cardiogenesis

AIMS

MicroRNAs (miRNAs) play critical roles during the development of the cardiovascular system. Blocking miRNA biosynthesis in embryonic hearts through a conditional gene inactivation approach led to differential cardiac defects depending on the Cre drivers used in different studies. The goal of this study is to reveal the cardiogenic pathway that is regulated by the miRNA mechanism at midgestation, a stage that has not been evaluated in previous publications.

METHODS AND RESULTS

We specifically inactivated Dicer1, which is essential for generation of functional mature miRNAs, in the myocardium by crossing cTnt-Cre mice with Dicer1(loxP) mice. cTnt-Cre efficiently inactivates target genes in cardiomyocytes at midgestation. All mutants died between E14.5 and E16.5 with severe myocardial wall defects, including reduced cell proliferation, increased cell death, and spongy myocardial wall. Expression of TGFβ type I receptor (Tgfbr1), which encodes the Type I receptor of TGFβ ligands, was up-regulated in mutant hearts. As expected, TGFβ activity was increased in Dicer1-inactivated hearts. Our further molecular analysis suggested that Tgfbr1 is a direct target of three miRNAs. Reducing TGFβ activities using a pharmacological inhibitor on in vitro cultured hearts, or through an in vivo genetic approach, partially rescued the cardiac defects caused by Dicer1 inactivation.

CONCLUSIONS

We show for the first time that TGFβ signalling is directly regulated by the miRNA mechanism during myocardial wall morphogenesis. Increased TGFβ activity plays a major role in the cardiac defects caused by myocardial deletion of Dicer1. Thus, miRNA-mediated regulation of TGFβ signalling is indispensable for normal cardiogenesis.

Left ventricular non-compaction presenting with heart failure and intramural thrombus

Left ventricular non-compaction (LVNC) is a rare disorder caused by the arrest of myocardial compaction during embryogenesis, leading to a non-compacted endocardial layer with marked trabeculations. The diagnosis is primarily based on echocardiographic demonstration of a spongy myocardium. Here, we present a young male with LVNC presenting with left heart failure and multiple left ventricular thrombi. We also review the presentation, diagnosis and management of this condition.

The role of cardiac magnetic resonance imaging in the assessment of non-ischemic cardiomyopathy

Cardiovascular magnetic resonance imaging (CMR) plays an increasing role in the assessment of patients with various cardiovascular disorders. Given its enhanced spatial resolution, improved tissue characterization, and lack of ionizing radiation, it has become the test of choice in the evaluation of patients with new-onset cardiomyopathy of unknown etiology. In this paper, we will review the role of CMR in the evaluation of patients with various types of non-ischemic cardiomyopathy.

Self and non-self discrimination is needed for the existence rather than deletion of autoimmunity: the role of regulatory T cells in protective autoimmunity

Autoimmune T cells have been viewed for decades as an outcome of immune system malfunction, and specifically as a failure to distinguish between components of self and non-self. The need for discrimination between self and non-self as a way to avoid autoimmunity has been repeatedly debated over the years. Recent studies suggest that autoimmunity, at least in the nervous system, is the body's defense mechanism against deviations from the normal. The ability to harness neuroprotective autoimmunity upon need is evidently allowed by naturally occurring CD4+CD25+ regulatory T cells, which are themselves controlled by brain-derived compounds. These findings challenge widely accepted concepts of the need for discrimination between self and non-self, as they suggest that while such discrimination is indeed required, it is needed not as a way to avoid an anti-self response but to ensure its proper regulation. Whereas a response to non-self can be self-limited by a decreased presence of the relevant antigen, the response to self needs a mechanism for strict control, such as that provided by the naturally occurring regulatory T cells.