Left ventricular noncompaction associated with hypertrophic cardiomyopathy: Echocardiographic diagnosis and genetic analysis of a new pedigree in China

Different Phenotypes of Sarcomeric MyBPC3-Cardiomyopathy in the Same Family: Hypertrophic, Left Ventricular Noncompaction and Restrictive Phenotypes (in Association with Sarcoidosis)

The same variants in sarcomeric genes can lead to different cardiomyopathies within the same family. This gave rise to the concept of a continuum of sarcomeric cardiomyopathies. However, the manifestations and evolution of these cardiomyopathies in pathogenic variant carriers, including members of the same family, remains poorly understood. We present a case of familial sarcomeric cardiomyopathy caused by heterozygous truncating pathogenic variant p.Q1233* in cardiac myosin-binding protein C (MyBPC3) gene. The proband was first diagnosed with restrictive cardiomyopathy combined with left ventricular noncompaction (LVNC) and sarcoidosis at the age of 64. The predominantly restrictive phenotype of cardiomyopathy is considered to be a result of interaction between LVNC and sarcoid myocarditis. His 39-year-old son and 35-year-old daughter have identical non-obstructive asymmetric hypertrophic cardiomyopathy. The risk of sudden cardiac death in the son is high due to myocardial fibrosis, ischemia and nonsustained VT. We assume that both phenotypes in the family may have originally been different or there may have been a gradual transformation of the hypertrophic phenotype into LVNC. Myocarditis is regarded as an important epigenomic modifier of sarcomeric cardiomyopathy. In the proband and his son, cardioverter-defibrillators were implanted, and the proband experienced appropriate shocks due to ventricular tachycardia/fibrillation. The proband was also treated with corticosteroids. His death at the age of 69 years occurred due to acute gastric hemorrhage accompanied by progressive heart failure. This report confirms the concept of the phenotypic continuum of sarcomeric cardiomyopathies and describes possible phenotypic patterns and their transformation over time.

Cardiac Amyloidosis in a Child Presenting with Syncope: The First Reported Case and a Diagnostic Dilemma

Cardiac amyloidosis is a rare cause of cardiomyopathy, reported exclusively in adults. We report the first known case presenting in childhood. A 12-year-old boy presented with syncope and diagnosed with ventricular non-compaction by echocardiography. Eventual genetic testing confirmed a TTR gene mutation associated with hereditary transthyretin amyloidosis.

Familial Atrial Enlargement, Conduction Disorder and Symmetric Cardiac Hypertrophy Are Early Signs of PRKAG2 R302Q

PRKAG2 cardiac syndrome (PS) is a rare inherited disease due to PRKAG2 gene mutation and characterized by Wolff-Parkinson-White syndrome (WPWs), conduction system lesions and myocardial hypertrophy. It can also lead to serious consequences, such as sudden death. But the genetic and clinical heterogeneity makes the early diagnosis of PS difficult. Here we studied a family with familial hypertrophic cardiomyopathy and other diverse manifestations. Gene analysis identified a missense mutation (Arg302Gln) in the five affected subjects of the family. The electrocardiograph performance of the five was composed of sinus bradycardia (SB), WPWs, right bundle branch block (RBBB), atrioventricular block (AVB), left bundle branch block (LBBB), supraventricular tachycardia (SVT) and atrial premature beat (APB). Among them, the youngest one began to show paroxysmal palpitation at the age of nine and was confirmed to have WPWs at 17 years old; two members progressed over time to serious conduction damage, and the proband received a pacemaker at the age of 27 due to AVB. Besides, according to cardiac magnetic resonance and echocardiography, the youngest one showed symmetric hypertrophy; three older members showed asymmetric myocardial hypertrophy characterized with a diffuse pattern of middle-anterior-lateral-inferior wall hypertrophy and especially interventricular septal hypertrophy; all five affected patients showed atrial enlargement regardless of myocardial hypertrophy at an earlier stage. In conclusion, the conduction system disorder, familial atrial enlargement and symmetric cardiac hypertrophy may occur in the early stage of PRKAG2 R302Q mutation.

Novel α-Actin Gene Mutation p.(Ala21Val) Causing Familial Hypertrophic Cardiomyopathy, Myocardial Noncompaction, and Transmural Crypts. Clinical-Pathologic Correlation

Background

Mutations of α‐actin gene (ACTC1) have been phenotypically related to various cardiac anomalies, including hypertrophic cardiomyopathy and dilated cardiomyopathy and left ventricular (LV) myocardial noncompaction. A novel ACTC mutation is reported as cosegregating for familial hypertrophic cardiomyopathy and LV myocardial noncompaction with transmural crypts.

Methods and Results

In an Italian family of 7 subjects, 4 aged 10 (II‐1), 14 (II‐2), 43 (I‐4) and 46 years (I‐5), presenting abnormal ECG changes, dyspnea and palpitation (II‐2, I‐4, and I‐5), and recurrent cerebral ischemic attack (I‐5), underwent 2‐dimensional echo, cardiac magnetic resonance, Holter monitoring, and next‐generation sequencing gene analysis. Patients II‐2 and I‐5 with ventricular tachycardia underwent a cardiac invasive study, including coronary with LV angiography and endomyocardial biopsy. In all the affected members, ECG showed right bundle branch block and left anterior hemiblock with age‐related prolongation of QRS duration. Two‐dimensional echo and cardiac magnetic resonance documented LV myocardial noncompaction in all and in I‐4, I‐5, and II‐2 a progressive LV hypertrophy up to 22‐mm maximal wall thickness. Coronary arteries were normal. LV angiography showed transmural crypts progressing to spongeous myocardial transformation with LV dilatation and dysfunction in the oldest subject. At histology and electron microscopy detachment of myocardiocytes were associated with cell and myofibrillar disarray and degradation of intercalated discs causing disanchorage of myofilaments to cell membrane. Next‐generation sequencing showed in affected members an unreported p.(Ala21Val) mutation of ACTC.

Conclusions

Novel p.(Ala21Val) mutation of ACTC1 causes myofibrillar and intercalated disc alteration leading to familial hypertrophic cardiomyopathy and LV myocardial noncompaction with transmural crypts.

Imaging cardiac morphology in hypertrophic cardiomyopathy: recent advances

PURPOSE OF REVIEW

To describe new cardiac MRI (CMR) findings on cardiac structure and myocardial composition in hypertrophic cardiomyopathy (HCM).

RECENT FINDINGS

Quantitative CMR assessment of replacement fibrosis and interstitial fibrosis can risk stratify HCM patients for adverse outcomes. Patients with global LVH (increased LV mass index) have more adverse outcomes. The HCM phenotype with a spiral distribution of hypertrophy entails a good prognosis. Myocardial noncompaction can be associated with HCM, as are papillary muscle and mitral apparatus abnormalities. Genotype positive, phenotype negative relatives of HCM probands may be detected by myocardial motion abnormalities. Emerging CMR methods for myocardial fiber disarray and altered myocardial stiffness may shed more light on cardiac structure, function and outcomes in HCM in coming years.

SUMMARY

CMR structural features of HCM, including severity and distribution of hypertrophy and fibrosis, can augment clinical evaluation of HCM. New CMR phenotypes, associated papillary muscle, mitral leaflet and myocardial noncompaction abnormalities, role of left atrial enlargement, findings in genotype positive phenotype negative HCM, and emerging methods for the detection of myocardial fiber disarray and altered myocardial stiffness may shed light in coming years.

Evaluation and management of left ventricular noncompaction cardiomyopathy

Left ventricular (LV) noncompaction cardiomyopathy (LVNC) is a form of cardiomyopathy in which trabeculations fail to "compact" with the left ventricular endocardium during fetal cardiac development and is classically associated with subsequent impairment of LV function, significant mortality, ventricular dysrhythmias, and embolic phenomena. As awareness and medical imaging quality have improved, it is becoming easier to identify trabeculations that traverse the LV cavity and serve as a distinguishing feature of this disorder. Differentiating true noncompaction from mild increases in trabeculations requires prudent imaging and clinical correlation. This review seeks to discuss the potential methods of evaluating left ventricular trabeculations, the role of increased trabeculations in cardiovascular disease, and how their presence may affect clinical management.