Isolated noncompaction of the left ventricular myocardium in the adult is an autosomal dominant disorder in the majority of patients

Value of cardiovascular MR in diagnosing left ventricular non-compaction cardiomyopathy and in discriminating between other cardiomyopathies

Objectives

To analyse the value of cardiovascular magnetic resonance (CMR)-derived myocardial parameters to differentiate left ventricular non-compaction cardiomyopathy (LVNC) from other cardiomyopathies and controls.

Methods

We retrospectively analysed 12 patients with LVNC, 11 with dilated and 10 with hypertrophic cardiomyopathy and compared them to 24 controls. LVNC patients had to fulfil standard echocardiographic criteria as well as additional clinical and imaging criteria. Cine steady-state free precession and late gadolinium enhancement (LGE) imaging was performed. The total LV myocardial mass index (LV-MMI), compacted (LV-MMI_compacted), non-compacted (LV-MMI_{non-compacted}), percentage LV-MM_{non-compacted}, ventricular volumes and function were calculated. Data were compared using analysis of variance and Dunnett’s test. Additionally, semi-quantitative segmental analyses of the occurrence of increased trabeculation were performed.

Results

Total LV-MMI_{non-compacted} and percentage LV-MM_{non-compacted} were discriminators between patients with LVCN, healthy controls and those with other cardiomyopathies with cut-offs of 15 g/m² and 25 %, respectively. Furthermore, trabeculation in basal segments and a ratio of non-compacted/compacted myocardium of ≥3:1 were criteria for LVNC. A combination of these criteria provided sensitivities and specificities of up to 100 %. None of the LVNC patients demonstrated LGE.

Conclusions

Absolute CMR quantification of the LV-MMI_{non-compacted} or the percentage LV-MM_{non-compacted} and increased trabeculation in basal segments allows one to reliably diagnose LVNC and to differentiate it from other cardiomyopathies.

Key Points

• Cardiac magnetic resonance imaging can reliably diagnose left ventricular non-compaction cardiomyopathy.

• Differentiation of LVNC from other cardiomyopathies and normal hearts is possible.

• The best diagnostic performance can be achieved if combined MRI criteria for the diagnosis are used.

Left ventricular noncompaction: a 25-year odyssey

Left ventricular noncompaction (LVNC) is a cardiomyopathy associated with sporadic or familial disease, the latter having an autosomal dominant mode of transmission. The clinical features associated with LVNC vary from asymptomatic to symptomatic patients, with the potential for heart failure, supraventricular and ventricular arrhythmias, thromboembolic events, and sudden cardiac death. Echocardiography is the diagnostic modality of choice, revealing the pathognomonic features of a thick, bilayered myocardium; prominent ventricular trabeculations; and deep intertrabecular recesses. Widespread use and advances in the technology of echocardiography and cardiac magnetic resonance imaging are increasing awareness of LVNC, and cardiac magnetic resonance imaging is improving the ability to stage the severity of the disease and potential for adverse clinical consequences. Study of LVNC through research in embryology, imaging, and genetics has allowed enormous strides in the understanding of this heterogeneous disease over the past 25 years.

The cell biology of disease: cellular mechanisms of cardiomyopathy

The heart exhibits remarkable adaptive responses to a wide array of genetic and extrinsic factors to maintain contractile function. When compensatory responses are not sustainable, cardiac dysfunction occurs, leading to cardiomyopathy. The many forms of cardiomyopathy exhibit a set of overlapping phenotypes reflecting the limited range of compensatory responses that the heart can use. These include cardiac hypertrophy, induction of genes normally expressed during development, fibrotic deposits that replace necrotic and apoptotic cardiomyocytes, and metabolic disturbances. The compensatory responses are mediated by signaling pathways that initially serve to maintain normal contractility; however, persistent activation of these pathways leads to cardiac dysfunction. Current research focuses on ways to target these specific pathways therapeutically.

Sarcomere Gene Mutations in Isolated Left Ventricular Noncompaction Cardiomyopathy Do Not Predict Clinical Phenotype

Background—

Left ventricular noncompaction of the myocardium (LVNC) has been recognized as a cardiomyopathy with a genetic etiology. Mutations in genes encoding sarcomere proteins were shown to be associated with LVNC. We evaluated the potential clinical impact of genetic analysis of sarcomere genes in patients with LVNC.

Methods and Results—

We identified 5 mutations in cardiac myosin-binding protein C ( MYBPC3 ) and 2 mutations in α-tropomyosin ( TPM1 ) in a cohort of unrelated adult probands with isolated LVNC. The mutations in MYBPC3 and TPM1 and in 6 other previously reported sarcomere genes in this cohort resulted in a total of 18 (29%) heterozygous mutations in 63 probands. β-myosin heavy chain ( MYH7 ) was the most prevalent disease gene and accounts for 13% of cases, followed by MYBPC3 (8%). Comparing sarcomere mutation-positive and mutation-negative LVNC probands showed no significant differences in terms of average age, myocardial function, and presence of heart failure or tachyarrhythmias at initial presentation or at follow-up. Familial disease was found in 16 probands of whom 8 were sarcomere mutation positive. Nonpenetrance was detected in 2 of 8 mutation-positive families with LVNC.

Conclusions—

Mutations in sarcomere genes account for a significant (29%) proportion of cases of isolated LVNC in this cohort. The distribution of disease genes confirms genetic heterogeneity and opens new perspectives in genetic testing in patients with LVNC and their relatives at high risk of inheriting the cardiomyopathy. The presence or absence of a sarcomere gene mutation in LVNC cannot be related to the clinical phenotype.

Familal left ventricular hypertrabeculation (noncompaction) is myopathic

BACKGROUND

Left-ventricular hypertrabeculation/noncompaction(LVHT) is a cardiac abnormality of unknown aetiology, frequently associated with arrhythmias, heart failure, and embolism. In most cases LVHT is associated with neuromuscular disorders (NMDs) or other rare non-neuromuscular genetic syndromes. Occasionally, LVHT occurs familiarly.

METHODS AND RESULTS

Invited for a cardiologic investigation were all first-degree relatives of index patients with LVHT who attended the cardiologic department. Altogether 25 relatives of 15 index patients from 15 families were investigated. Three members each were investigated in 3 families, 2 patients each in 4 families and 1 member each in 8 families. Among the 25 relatives from the 15 families, LVHT was found in 4 of them. Accordingly, familial LVHT was detected in 4 of the 15 investigated families (27%). Among the 4 relatives with LVHT, extension and morphology were similar to the appropriate index patient in 2 families. A NMD was diagnosed in three of the four relatives (75%) with familial LVHT. One relative without LVHT presented with a history of Fallot's tetralogy, and two relatives each presented with thickening of the left-ventricular myocardium.

CONCLUSIONS

LVHT is familial in at least 27% of the patients with LVHT. LVHT may differ between relatives in some of the patients with familial LVHT. Familial LVHT is associated with a NMD in the majority of the cases. Relatives of LVHT patients may present with cardiac abnormalities other than LVHT.

Cardiomyopathies--misdiagnosed as Sudden Infant Death Syndrome (SIDS)

Cardiomyopathies are an important and heterogenous group of diseases. With the identification of several new disease entities over the past decade, advances in diagnosis and precise causation, some disease definitions have become outdated. The past decade has witnessed a rapid evolution of molecular genetics in cardiology, e.g. myocardial diseases (Hypertrophic cardiomyopathy-HCM, Arrhythmogenic right ventricular cardiomyopathy-ARVCM) and channelopathies (Long QT syndrome-LQTS, Brugada syndrome-BrS, Catecholaminergic Polymorphic Ventricular Tachycardia-CPVT and Short QT syndrome-SQTS) as diseases predisposing to potentially lethal ventricular tachyarrhythmias. Beside the detection of mutations in several genes, histological and immunohistochemical findings can point to a cardiomyopathy as underlying disease. Therefore, previous microscopical investigations of different parts of the myocardium can help to select those cases of suspected Sudden Infant Death Syndrome (SIDS), where a search for genetic mutations can lead to a diagnosis explaining the sudden and unexpected death.

Isolated left ventricular noncompaction cardiomyopathy accompanied by severe mitral regurgitation

Isolated left ventricular noncompaction cardiomyopathy (IVNC) is a cardiomyopathy thought to be caused by arrest of normal embryogenesis of the endocardium and myocardium. This abnormality is often associated with other congenital cardiac defects. A 21-year-old man presented to the emergency department with worsening exertional dyspnea during the previous 2 months. Two-dimensional and Doppler echocardiography revealed an enlarged left atrium (LA) and a markedly dilated left ventricle (LV) with preserved LV systolic function, severe mitral valve regurgitation, and prolapse due to chordae rupture. The myocardium of the LV and right ventricle (RV) had excessively prominent trabeculations and deep intertrabecular recesses. He is the first patient in Korea who has undergone mitral valve replacement surgery because of severe mitral valve regurgitation and prolapse due to chordae rupture accompanied by IVNC.

Acute cardiac and neurologic decompensation in a high school athlete

A 19-year-old African American man presented to a local emergency room with atrial flutter, dysarthria, and left-sided hemiparesis. He was previously healthy and a successful high school athlete. The patient decompensated and went into cardiac arrest. Two-dimensional echocardiography revealed biventricular dilation, severe systolic dysfunction, and a spongy myocardial appearance. Postmortem examination was diagnostic of biventricular noncompaction. Such a fulminant presentation of isolated ventricular noncompaction in a previously healthy and physically fit individual has not yet been described.

Sarcomere mutations in cardiomyopathy with left ventricular hypertrabeculation

BACKGROUND

Mutations in the genes encoding sarcomere proteins have been associated with both hypertrophic and dilated cardiomyopathy. Recently, mutations in myosin heavy chain (MYH7), cardiac actin (ACTC), and troponin T (TNNT2) were associated with left ventricular noncompaction, a form of cardiomyopathy characterized with hypertrabeculation that may also include reduced function of the left ventricle.

METHODS AND RESULTS

We used clinically available genetic testing on 3 cases referred for evaluation of left ventricular dysfunction and noncompaction of the left ventricle and found that all 3 individuals carried sarcomere mutations. The first patient presented with neonatal heart failure and was referred for left ventricular noncompaction cardiomyopathy. Genetic testing found 2 different mutations in MYBPC3 in trans. The first mutation, 3776delA, Q1259fs, rendered a frame shift at 1259 of cardiac myosin-binding protein C and the second mutation was L1200P. The frameshift mutation was also found in this mother who displayed mild echocardiographic features of cardiomyopathy, with only subtle increase in trabeculation and an absence of hypertrophy. A second pediatric patient presented with heart failure and was found to carry a de novo MYH7 R369Q mutation. The third case was an adult patient with dilated cardiomyopathy referred for ventricular hypertrabeculation. This patient had a family history of congestive heart failure, including pediatric onset cardiomyopathy where 3 individuals in the family were found to have the MYH7 mutation R1250W.

CONCLUSIONS

Genetic testing should be considered for cardiomyopathy with hypertrabeculation.

Is left ventricular noncompaction in children truly an isolated lesion?

Left ventricular noncompaction (LVNC) is a form of cardiomyopathy resulting from a disorder of endomyocardial morphogenesis. It has been associated with significant morbidity and mortality. The aim of this study was to characterize associated cardiac findings in children with LVNC and to identify risk factors associated with increased mortality. From our echocardiography database, we identified 46 patients diagnosed with LVNC between December 1999 and February 2005. The mean age at presentation was 3.6 +/- 5.6 years, and the mean duration of follow-up was 1.9 +/- 2.1 years. Left ventricular ejection fraction was decreased in 24 patients (52%; mean 39.5% +/- 13.1%). Thirty-six patients (78%) had associated cardiac lesions, including atrial septal defect (n = 16 [35%]), ventricular septal defect (n = 17 [37%]), patent ductus arteriosus (n = 14 [30%]), and Ebstein's anomaly (n = 5 [11%]). Electrocardiogram abnormalities were found in 80% of patients; most commonly they included left (n = 15 [43%]) and right ventricular hypertrophy (n = 19 [54%]). Documented arrhythmias included ectopic atrial rhythm (n = 2), junctional rhythm (n = 2), supraventricular tachycardia (n = 2), and ventricular tachycardia (n = 1). Overall mortality was 20%, and there was no association with ejection fraction, morphologic defect, or arrhythmia. Mean age at diagnosis in survivors (4.5 +/- 6.1 years) was higher than nonsurvivors (0.4 +/- 0.7 years) (p < 0.0001). LVNC is a rarely isolated form of cardiomyopathy, and it is associated with significant additional cardiac abnormalities. Although it does not have an invariably fatal course, early presentation in infancy does carry an increased risk of mortality.

[Noncompaction of the left ventricular myocardium]

BACKGROUND

Noncompaction of the left ventricular myocardium is recently described as a cause of left ventricular dysfunction. In the article, we describe epidemiological and clinical aspects of this condition, which presents clinically at any age.

MATERIAL AND METHODS

This article is based on a review of articles from our own literature archive and relevant references in these articles.

RESULTS

Ventricular noncompaction results from an arrest in the normal endomyocardial embryogenesis, and often leads to heart failure, thrombo-embolic events and/or ventricular arrhythmias. The disorder is diagnosed by two-dimensional echocardiography or magnetic resonance imaging of the heart. The changes are typically seen in the apex and distal and middle segments of the inferior and lateral walls of the left ventricle. The affected segments of the myocardium have a two-layered structure: a compacted thin epicardial layer and an endocardial layer consisting of a prominent trabecular meshwork with deep intertrabecular spaces. The condition can be isolated with or without extracardiac disorders, or can be associated with other cardiac malformations.

INTERPRETATION

It is essential not to miss the findings of noncompaction, as the condition may lead to serious heart failure, thrombo-embolic events, ventricular tachyarrythmias or death. Early recognition of noncompaction may give better follow-up and management of patients with this condition.

Cardiac re-synchronization therapy in a patient with isolated ventricular non-compaction: a case report

Isolated ventricular non-compaction (IVNC) is a rare, congenital, unclassified cardiomyopathy characterized by prominent trabecular meshwork and deep recesses. Major clinical manifestations of IVNC are heart failure, atrial and ventricular arrhythmias, and thrombo-embolic events. We describe a case of a 69-year-old woman in whom the diagnosis of IVNC was discovered late, whereas former echocardiographic examinations were considered normal. She was known for systolic left ventricular dysfunction for 3 years and then became symptomatic (NYHA III). In the past, she suffered from multiple episodes of deep vein thrombosis and pulmonary embolism. Electrocardiogram revealed a wide QRS complex, and transthoracic echocardiography showed typical apical thickening of the left and right ventricular myocardial wall with two distinct layers. The ratio of non-compacted to compacted myocardium was >2:1. Cardiac MRI confirmed the echocardiographic images. Cerebral MRI revealed multiple ischaemic sequellae. In view of the persistent refractory, heart failure in medical treatment of patients with classical criteria for cardiac re-synchronization therapy, as well as the ventricular arrhythmias, a biventricular automatic intracardiac defibrillator (biventricular ICD) was implanted. The 2-year follow-up period was characterized by improvement of NYHA functional class from III to I and increasing in left ventricular function. We hereby present a case of IVNC with favourable outcome after biventricular ICD implantation. Cardiac re-synchronization therapy could be considered in the management of this pathology.

Genetic heterogeneity of left-ventricular noncompaction cardiomyopathy

Isolated noncompaction of the ventricular myocardium (INVM) sometimes referred to as spongy myocardium is a rare, congenital and also acquired cardiomyopathy. It appears to divide the presentation into neonatal, childhood and adult forms of which spongy myocardium and systolic dysfunction is the commonality. The disorder is characterized by a left ventricular hypertrophy with deep trabeculations, and with diminished systolic function, with or without associated left ventricular dilation. In half or more of the cases, the right ventricle is also affected. The sporadic type, however, in some patients, may be due to chromosomal abnormalities and the occurrence of familial incidence. Isolated noncompaction of the left ventricular myocardium in the majority of adult patients is an autosomal dominant disorder. The familial and X-linked disorders have been described by various authors. We here describe the genetic background of this disorder: some of the most mutated genes that are responsible for the disease are (G4.5 (tafazzin gene): alpha-dystrobrevin gene (DTNA); FKBP-12 gene; lamin A/C gene; Cypher/ZASP (LIM, LDB3) gene); and some genotype-phenotype correlations (Becker muscular dystrophy, Emery-Dreifuss muscular dystrophy or Barth syndrome) based on the literature review.

Left ventricular noncompaction and cardiomyopathy: cause, contributor, or epiphenomenon?

PURPOSE OF REVIEW

To discuss unresolved issues pertaining to aetiology and diagnosis of isolated left ventricular noncompaction.

RECENT FINDINGS

Left ventricular noncompaction may be sporadic or familial and is linked to mutations in mitochondrial, cytoskeletal, Z-line, and sarcomeric proteins. Severe childhood manifestations include fetal hydrops or sudden infant death syndrome. Adults with severe phenotypes have a similarly guarded prognosis due to heart failure, arrhythmia and thromboembolism. Conversely, healthy individuals may fulfil current imaging criteria for diagnosis. Left ventricular noncompaction is also observed in families with hypertrophic or dilated cardiomyopathy, casting doubt on its acceptance as a distinct disease entity.

SUMMARY

The extent of myocardial compaction may be a continuous trait within the population. Sensitive imaging techniques may detect subtle variations in morphology that fall within the normal range, underscoring the need for more restrictive diagnostic criteria, as in mitral valve prolapse. Conversely, rather than being a root cause of myocardial dysfunction, left ventricular noncompaction may represent a secondary consequence of a genetic alteration, well-tolerated when the heart is otherwise normal. In the presence of a pathogenic mutation, disruption to myocyte function at a molecular level may be the primary disease determinant, with noncompaction arising as a maladaptive remodelling response that compounds the disease process through subendocardial ischaemia and fibrosis.

Prenatal diagnosis of omphalocele and left atrial isomerism (polysplenia) including complex congenital heart disease with ventricular noncompaction cardiomyopathy

We report prenatal diagnosis of a rare constellation of findings, including omphalocele and polysplenia (left atrial isomerism [LAI]) with cardiac malformations including ventricular noncompaction (VNC) cardiomyopathy. The heterotaxy syndromes (polysplenia or LAI and asplenia or right atrial isomerism) are rare syndromes in which organs that are usually asymmetric are abnormally symmetric or abnormally positioned. Complex congenital heart disease is frequently associated with heterotaxy, with the heart being substantially affected in both structure and orientation. Heterotaxy has also been occasionally associated with a rare type of cardiomyopathy: VNC, described by Feldt et al and Ozkutlu et al. Omphalocele is a relatively common birth defect that is due to failure of the abdominal wall to close in association with return of the bowel in the first trimester. We report a case in which all of these findings were present. The cardiac findings were previously included in a pathology series on LAI with VNC by Friedberg et al; however, to our knowledge, pre-natal diagnosis of this unique collection of findings has not been reported previously.

Mutations in sarcomere protein genes in left ventricular noncompaction

BACKGROUND

Left ventricular noncompaction constitutes a primary cardiomyopathy characterized by a severely thickened, 2-layered myocardium, numerous prominent trabeculations, and deep intertrabecular recesses. The genetic basis of this cardiomyopathy is still largely unresolved. We speculated that mutations in sarcomere protein genes known to cause hypertrophic cardiomyopathy and dilated cardiomyopathy may be associated with left ventricular noncompaction.

METHODS AND RESULTS

Mutational analysis in a cohort of 63 unrelated adult probands with left ventricular noncompaction and no other congenital heart anomalies was performed by denaturing high-performance liquid chromatography analysis and direct DNA sequencing of 6 genes encoding sarcomere proteins. Heterozygous mutations were identified in 11 of 63 samples in genes encoding beta-myosin heavy chain (MYH7), alpha-cardiac actin (ACTC), and cardiac troponin T (TNNT2). Nine distinct mutations, 7 of them in MYH7, 1 in ACTC, and 1 in TNNT2, were found. Clinical evaluations demonstrated familial disease in 6 of 11 probands with sarcomere gene mutations. MYH7 mutations segregated with the disease in 4 autosomal dominant LVNC kindreds. Six of the MYH7 mutations were novel, and 1 encodes a splice-site mutation, a relatively unique finding for MYH7 mutations. Modified residues in beta-myosin heavy chain were located mainly within the ATP binding site.

CONCLUSIONS

We conclude that left ventricular noncompaction is within the diverse spectrum of cardiac morphologies triggered by sarcomere protein gene defects. Our findings support the hypothesis that there is a shared molecular etiology of different cardiomyopathic phenotypes.

Isolated noncompaction of the ventricular myocardium: contemporary diagnosis and management

Noncompaction of the ventricular myocardium is a rare form of cardiomyopathy that has been described since the early 1990s. However, noncompaction remains frequently overlooked, in part due to the limited awareness of its unique clinical and imaging characteristics. Contemporary diagnosis has been facilitated by the introduction of specific morphologic criteria by echocardiography and cardiac magnetic resonance. Management issues revolve around the management of heart failure, arrhythmias, and thromboembolic events in order to prevent the significant morbidity and even mortality that has been associated with this entity. Finally, the genetics of noncompaction have been diverse and an issue of clinical importance as it relates to screening of first-degree relatives of affected patients. Two recent cases are presented and many of the contemporary issues in diagnosis and management, based on an extensive review of the literature, are addressed.

Isolated left ventricular non-compaction: the case for abnormal myocardial development

Isolated ventricular non-compaction is an increasingly commonly diagnosed myocardial disorder characterised by excessive and prominent trabeculation of the morphologically left, and occasionally the right, ventricle. This is associated with high rates of thromboembolism, cardiac failure, and cardiac arrhythmia. Recent improvements in understanding the embryonic processes underlying ventricular formation have led to the hypothesis that ventricular non-compaction is due to a failure of normal ventriculogenesis, leading to abnormal myocardium which may present clinically many years later. Experimental work in animal models provides several candidate transcription factors and signalling molecules that could, in theory, cause ventricular non-compaction if disrupted.

Successful outcome in a pregnant woman with isolated noncompaction of the left ventricular myocardium

A 24-year-old pregnant woman was referred to our hospital for the evaluation of her cardiac function. An electrocardiogram showed Wolff-Parkinson-White syndrome. Echocardiography revealed prominent trabeculation and deep intertrabecular recesses at the left ventricular apex and mid-portion of the inferior and lateral wall, with an impaired ejection fraction. She was diagnosed as having an isolated noncompaction of the ventricular myocardium (INVM). As the pregnancy progressed, severe restrictive hemodynamics became apparent. In consideration of the fetal growth, we decided to deliver the fetus by cesarean section at 32 weeks gestation; the patient successfully delivered a female infant. Interestingly, echocardiography demonstrated INVM in both the child and mother. This report is the first description of a successful pregnancy in a patient with familial INVM.

Isolated ventricular non-compaction: clinical study and genetic review

Isolated non-compaction of the ventricular myocardium (INVM), sometimes referred to as 'spongy myocardium', is a congenital and exceedingly rare cardiomyopathy. Isolated ventricular non-compaction occurs in the absence of other structural heart diseases and, hypothetically, it is due to the arrest of myocardial morphogenesis. Isolated non-compaction of the ventricular myocardium may manifest itself from infancy to young adulthood with a high mortality rate. Both sexes are affected. In our study, we present a case of INVM (left and right ventricles) in a 3-year-old girl, diagnosed by two-dimensional echocardiography. The anomaly presented as a restrictive cardiomyopathy. The girl was admitted to our hospital with heart failure, when she was 10 months old. She was treated with dopamine, digoxin, furosemide, spironolactone, and acenocoumarol and her condition improved. Presently, the girl remains asymptomatic and for 3 years of follow-up, her development has been almost normal. We here describe the genetic background of this disorder (based on a literature review).

Echocardiography in the diagnosis and management of isolated left ventricular noncompaction: case reports and review of the literature

Isolated left ventricular noncompaction (IVNC) is a congenital cardiomyopathy characterized by a loosened spongy myocardium. Recognition of this condition is extremely important because of its high mortality and morbidity due to progressive heart failure, thromboembolic events, and ventricular arrhythmias. However, IVNC is commonly misdiagnosed because of the lack of knowledge about this rare disorder. We report 2 patients with the characteristic echocardiographic presentation for IVNC. Echocardiography is the procedure of choice to confirm the diagnosis and perform follow-up in patients with IVNC; therefore, it is important to make echocardiographers more familiar with this condition.

Elderly manifestation of non-compaction of the ventricular myocardium

Non-compaction of the ventricular myocardium (NCVM) is a rare disorder of myocardial morphogenesis usually diagnosed in paediatric age associated with high mortality rates. Among reported cases, NCVM has been described in only six patients > or = 70 years. We describe the case of a 74-year-old male with NCVM involving the left ventricle, representing one of the oldest patients ever reported in the literature. Of note, this case was characterized by late appearance of NCVM and rapid deterioration of clinical conditions. The wide age range of symptom onset from prenatal to geriatric age supports the hypothesis that NCVM is a multifactorial rather than a simple congenital disorder.

Isolated ventricular non-compaction of the myocardium in adults

Isolated ventricular non-compaction (IVNC) in adults is a genetic cardiac disease of emerging importance with a distinct clinical and pathophysiological presentation. The body of evidence for the underlying genetic basis of the disease has also grown. Prognosis remains poor for patients with impaired systolic left ventricular function, as treatment options are very limited. The diagnosis of IVNC, however, is often missed, most often as a consequence of ignorance of the condition. The relevant clinical issues and the emerging concepts of the aetiology of IVNC are summarised.

Genetic analysis in patients with left ventricular noncompaction and evidence for genetic heterogeneity

Left ventricular noncompaction (LVNC) is a cardiomyopathy characterized by numerous excessively trabeculations and deep intertrabecular recesses. This study was performed to investigate Japanese LVNC patients for disease-causing mutations in a series of selected candidate genes. DNA was isolated from the peripheral blood of 79 cases including 20 familial cases and 59 sporadic cases. DNA samples were screened for mutations in the genes encoding G4.5 (TAZ), alpha-dystrobrevin (DTNA), alpha1-syntrophin (SNTA1), FK506 Binding protein 1A (FKBP1A or FKPB12: FKBP1A), and LIM Domain Binding protein 3 (Cypher/ZASP: LDB3), using single-strand conformational polymorphism analysis and DNA sequencing. DNA variants were identified in 6 of the 79 cases, including four familial cases and two sporadic cases. A splice acceptor mutation of intron 8 in TAZ (IVS8-1G>C) was identified in one family with isolated LVNC, resulting in deletion of exon 9 from mRNA. In a sporadic case of isolated LVNC and Barth syndrome (BTHS), a 158insC in exon 2 of TAZ resulting in a frame-shift mutation was identified. A 1876G>A substitution changing an aspartic acid to asparagine (D626N) was identified in LDB3 in four members of two families with LVNC. A 163G>A polymorphism was identified in LDB3, which changed a valine to isoleucine (V55I) in one patient with isolated LVNC. In addition, in a family with nonisolated LVNC, a 362C>T mutation was identified in DTNA. LVNC, like other forms of inherited cardiomyopathy, is a genetically heterogeneous disease, associated with variable clinical symptoms and can be inherited as an autosomal or X-linked recessive disorder.

Isolated non-compaction of the left ventricular myocardium in an adult treated with heart transplantation

Isolated left ventricular non-compaction is a rare unclassified cardiomyopathy characterized by arrest of normal embryogenesis that results in the persistence of intertrabecular recesses and the development of a spongy myocardium. The pathological diagnosis is often first established at autopsy. Described herein is the case of a 57-year-old man with isolated non-compaction of the left ventricle who had a 17 year history of worsening heart failure and was successfully treated with heart transplantation. To the authors' knowledge only seven adult patients with non-compaction cardiomyopathy have been reported to have undergone heart transplantation. Including the present case the mean age of the adult patients at transplantation was 39.5 years (range, 18-60 years). The male : female ratio was 3:1. Both ventricles were involved in 37.5% of cases. The mean follow up was 6.3 years (range, 2 months-17 years). One patient died because of a malignant tumor 9 years after transplantation. The morphological pattern of the isolated ventricular non-compaction represents a pathological entity discernible from other cardiomyopathies and should be classified as a specific cardiomyopathy. It is likely that surgical pathologists will encounter this entity more frequently due to involvement in transplantation teams.

The emerging role of MRI in the diagnosis and management of cardiomyopathies

Cardiac magnetic resonance (CMR) has emerged as an important tool for the evaluation of cardiomyopathies, providing highly accurate information on the macroscopic changes of cardiac morphology, function, and tissue composition. For myocardial tissue characterization, the technique of myocardial delayed enhancement is a potentially promising tool for diagnosis, management, and prognosis. Several CMR approaches are now available to better diagnose and prognosticate dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular disease, myocarditis, and other cardiomyopathies.

Splenic rupture and haemoperitoneum in a patient with non-compaction of the left ventricular myocardium

The anaesthetic and critical care management of blunt abdominal trauma in a patient previously diagnosed with non-compaction of the left ventricular myocardium (a rare autosomal dominant inherited disease) is reported. The management was influenced by the presence of an implanted automated internal defibrillator and treatment with anticoagulants because of the high frequency of severe arrhythmias and systemic embolism. The pathophysiology of ventricular non-compaction is reviewed briefly.

Isolated Ventricular Non-Compaction in Adults With Idiopathic Cardiomyopathy: Cardiac Magnetic Resonance and Pathologic Characterization of the Anomaly

Non-compaction of the ventricular myocardium is an anomaly of myocardial morphogenesis that leads to persistence of the embryonic myocardium with an excessively prominent trabecular meshwork and deep intertrabecular recesses. This report describes 3 cases of isolated left ventricular non-compaction in adults leading to terminal heart failure. We describe their distinctive myocardial histopathology and prospective diagnosis by cardiac magnetic resonance imaging (CMR). Heart transplantation was the only treatment option for all 3 of these severely ill patients. Isolated ventricular non-compaction should be considered in patients with severe idiopathic cardiomyopathy whose symptoms appear in early adulthood, and consideration given for early transplantation. Non-invasive imaging with CMR can confirm the diagnosis.

Noncompaction of the left ventricular myocardium diagnosed in pregnant woman and neonate

Noncompaction of the left ventricular myocardium (NCLV) is an uncommon congenital cardiomyopathy with poor prognosis. We describe a case of NCLV that developed in a pregnant woman and her neonate. A nulliparous woman was referred at 24 weeks' gestation due to dyspnea and fetal hydrops. Maternal echocardiography demonstrated NCLV with characteristic findings of prominent and excessive ventricular trabeculations and deep intertrabecular recesses in the left ventricle. An M-mode echocardiography suggested depressed left ventricular systolic function. A fetal echocardiography at 24 weeks' gestation demonstrated cardiomegaly, but morphologic findings were not definitive for NCLV. An emergency cesarean section was performed due to maternal heart failure. A neonatal echocardiography diagnosed NCLV with depressed left ventricular systolic function. The neonate died of cardiac failure on the second day of life. Autopsy confirmed the echocardiographic findings. Since patients with NCLV may develop heart failure, multidisciplinary management is mandatory. In addition, awareness of familial occurrence of NCLV should be kept in mind for early diagnosis in the fetus and neonate.

Cardiologic and neurologic findings in left ventricular hypertrabeculation/non-compaction related to wall thickness, size and systolic function

Left ventricular hypertrabeculation/noncompaction (LVHT) is a rare cardiac abnormality, diagnosed echocardiographically when >3 left ventricular trabeculations are visible in one image plane apically to the papillary muscles and intertrabecular spaces are perfused from the ventricular cavity. In the majority of the cases, LVHT is associated with neuromuscular disorders (NMD). LVHT occurs in dilated as well as in normally sized ventricles, with or without systolic dysfunction and wall thickening. Aim of the study was to assess whether cardiologic and neurologic findings differ between patients according to echocardiographically determined left ventricular size, systolic function and wall thickness. In 77 patients (19 f, mean age 52 years) LVHT was diagnosed. LVHT was assessed as 'dilative' (enddiastolic diameter >or=60 mm and fractional shortening <or=25%) in 43 cases, in 18 patients as 'hypertrophic' (interventricular septum and posterior wall >or=12 mm and fractional shortening >or=26%) and in the remaining 16 patients as 'normally-dimensioned'. Dilative LVHT patients were older than hypertrophic or normally-dimensioned LHVT patients. The prevalence of NMD was 63% in dilative LVHT, 67% in hypertrophic LVHT and 56% in normally-dimensioned LVHT. LHVT is more frequently found in dilated than hypertrophic ventricles. NMD are equally frequent in dilative, hypertrophic and normally-dimensioned LVHT. Cardiac abnormalities may progress with age.

Natural history and familial characteristics of isolated left ventricular non-compaction

AIMS

Non-compaction of the left ventricle (LVNC) is a disorder of endomyocardial morphogenesis that results in multiple trabeculations in the left ventricular myocardium. The current literature suggests that LVNC in adults is rare and associated with a poor prognosis. Given that the disorder is present at birth and that several studies have reported asymptomatic familial disease in some patients, we hypothesized that there is a long pre-clinical phase of the disease. The aim of this study was to define the prognosis and familial incidence of LVNC.

METHODS AND RESULTS

This study cohort comprised 45 patients (mean age at diagnosis 37 years) consecutively identified at a referral centre for cardiomyopathy over a 10-year period. Twenty-eight patients (62%) had dyspnoea at presentation; 41 (91%) an abnormal ECG; and 30 (66%) left ventricular dilatation and impaired systolic function. Nine patients (20%) had non-sustained ventricular tachycardia on 24 h Holter monitoring. Mean survival from death or transplantation was 97% at 46 months. There were three thromboembolic events in two patients (4%). On systematic family screening, 8 of 32 (25%) asymptomatic relatives had a range of echocardiographic abnormalities, including LVNC, LVNC with impaired systolic function, and left ventricular enlargement without LVNC.

CONCLUSION

This study demonstrates that LVNC is associated with a better prognosis than previously reported. In patients with familial disease, relatives may have features consistent with dilated cardiomyopathy rather than LVNC.

Novel Gene Locus for Autosomal Dominant Left Ventricular Noncompaction Maps to Chromosome 11p15

BACKGROUND

Left ventricular noncompaction (LVNC) is a congenital unclassified cardiomyopathy with numerous prominent trabeculations and deep intertrabecular recesses in a hypertrophied and hypokinetic myocardium. It has been reported to occur in isolation or in association with congenital heart disease. Mutations in the X-linked G4.5 gene are responsible for cases of isolated LVNC in male infants, but G4.5 mutations were not found in patients with clinical onset of disease in adulthood. In addition, several families with LVNC and an autosomal dominant pattern of inheritance suggest genetic heterogeneity.

METHODS AND RESULTS

We performed a genome-wide linkage analysis in a family with autosomal dominant LVNC and show that a locus containing the LVNC disease gene maps to chromosome 11p15. A peak 2-point logarithm of odds score of 5.06 was obtained with marker D11S902 at theta=0. Haplotype analysis defined a critical interval of 6.4 centimorgan between D11S1794 and D11S928 corresponding to a physical distance of 6.8 megabases. No disease-causing mutation was identified in 2 prime positional candidate genes, muscle LIM protein (MLP) and SOX6.

CONCLUSIONS

We have mapped a locus for autosomal dominant LVNC to a 6.8-megabase region on human chromosome 11p15. Identification of the disease gene will allow genetic screening and provide fundamental insight into the understanding of myocardial morphogenesis.

Isolated left ventricular noncompaction is rarely caused by mutations in G4.5, alpha-dystrobrevin and FK Binding Protein-12

Isolated left ventricular noncompaction (LVNC) is a form of cardiomyopathy that most commonly presents in infancy with a hypertrophic and dilated left ventricle characterized by deep trabeculations and intertrabecular recesses. Our goal was to determine the frequency of mutations in G4.5, alpha-dystrobrevin, and FK Binding protein-12 in isolated LVNC patients. No mutations were identified in 47 of the 48 patients studied, while a splice site acceptor site mutation of intron 10 of G4.5 was identified in one patient, resulting in the deletion of exon 10 from the mRNA.