The diagnosis and treatment of hypertrophic cardiomyopathy

A systematic literature review of economic evaluations and cost-of-illness studies of inherited cardiomyopathies

Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are commonly inherited heart conditions associated with a high risk of heart failure and sudden cardiac death. To understand the economic and societal disease burden, this study systematically identified and reviewed cost-of-illness (COI) studies and economic evaluations (EEs) of various interventions for HCM and DCM. A literature search was performed in MEDLINE, EMBASE, NHS EED, EconLit and Web of Science to identify COI studies and EEs published between 1 January 2010 and 28 April 2021. The selection of studies and their critical appraisal were performed jointly by two independent researchers. For the quality assessment, the 'Consensus on Health Economic Criteria' list was used. Two COI studies and 11 EEs were eligible for inclusion. Cost-effectiveness varied among interventions and depended on the targeted patient population. Both COI studies identified only hospitalisation costs in HCM. The mean study quality was high in EEs but low in COI studies. Most studies excluded costs for patients, caregivers and productivity losses. Overall, knowledge of the societal and economic burden of inherited cardiomyopathies is limited. Future research needs to include quality-adjusted life years and a broader range of costs to provide an information base for optimising care for affected patients.

Subtypes and Mechanisms of Hypertrophic Cardiomyopathy Proposed by Machine Learning Algorithms

Hypertrophic cardiomyopathy (HCM) is a relatively common inherited cardiac disease that results in left ventricular hypertrophy. Machine learning uses algorithms to study patterns in data and develop models able to make predictions. The aim of this study is to identify HCM subtypes and examine the mechanisms of HCM using machine learning algorithms. Clinical and laboratory findings of 143 adult patients with a confirmed diagnosis of nonobstructive HCM are analyzed; HCM subtypes are determined by clustering, while the presence of different HCM features is predicted in classification machine learning tasks. Four clusters are determined as the optimal number of clusters for this dataset. Models that can predict the presence of particular HCM features from other genotypic and phenotypic information are generated, and subsets of features sufficient to predict the presence of other features of HCM are determined. This research proposes four subtypes of HCM assessed by machine learning algorithms and based on the overall phenotypic expression of the participants of the study. The identified subsets of features sufficient to determine the presence of particular HCM aspects could provide deeper insights into the mechanisms of HCM.

Assessment of cardiac dimensions in children diagnosed with hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is an inherited autosomal dominant heart disease, characterized by increased left ventricular wall thickness and abnormal loading conditions. Imaging modalities are the first choice for diagnosis and risk stratification. Although heart dimensions have been characterized widely in HCM adults from cardiac imaging, there is limited information about children affected by HCM. The aim of this study is to evaluate left ventricular function and left heart dimensions in a small population of children diagnosed with HCM.

METHODS

A total of 16 (seven male, nine female) pediatric patients with an average age of 14.0 ± 2.5 years diagnosed with HCM at Great Ormond Street Hospital for Children were included in this study. Cardiac magnetic resonance (CMR) images were used to measure left and right ventricular dimensions, and septal and left ventricular free wall thicknesses in Simpleware ScanIP. The gender groups were compared using student t-test or non-parametric Mann-Whitney U-test depending on the sample distribution.

RESULTS

Differences in heart rate, left ventricular end-diastolic volume and end-diastolic volume index, left ventricular stroke volume and stroke volume index, left ventricular end-systolic long axis length, left ventricular end-systolic long axis length index, left ventricular end-diastolic mid-cavity diameter, left ventricular end-diastolic free wall thickness, left ventricular end-diastolic free wall thickness index, right ventricular end-diastolic long axis length were statistically significant in males and females.

CONCLUSION

Left ventricular wall and intraventricular septal thickness increase affecting left ventricle cavity dimensions and there may be differences in anatomical and physiological parameters in males and females affected by HCM.

Genetic Evaluation of Late-Onset Hypertrophic Cardiomyopathy: An Autobiographical Case Report

Cardiomyopathy, also known as a pathology with a cardiovascular cause, can be further differentiated into multiple categories including genetic. Strong correlations between genetic mutations in sarcomeric proteins and presentation of cardiomyopathies have been made. This case report describes the clinical diagnosis of my late-onset hypertrophic cardiomyopathy, which was brought upon by symptoms of chest pain and palpitations that started approximately two years ago and had mostly gone unnoticed during this period. As a geneticist, I decided to undergo genetic test upon diagnosis. These tests found a heterozygous variant of uncertain significance (VUS) in the ALPK3 gene, c.399dup (p.Gly134ArgfsTer30), and a heterozygous c.7552G>A (p.Val2518Ile) VUS in the desmoplakin (DSP) gene. This autobiographical case report hopes to shed light on the importance of genetic screening in the search for the etiology of clinical symptoms.

Anatomical-MRI Correlations in Adults and Children with Hypertrophic Cardiomyopathy

Hypertrophic Cardiomyopathy (HCM) is the most frequent hereditary cardiovascular disease and the leading cause of sudden cardiac death in young individuals. Advancements in CMR imaging have allowed for earlier identification and more accurate prognosis of HCM. Interventions aimed at slowing or stopping the disease’s natural course may be developed in the future. CMR has been validated as a technique with high sensitivity and specificity, very few contraindications, a low risk of side effects, and is overall a good tool to be employed in the management of HCM patients. The goal of this review is to evaluate the magnetic resonance features of HCM, starting with distinct phenotypic variants of the disease and progressing to differential diagnoses of athlete’s heart, hypertension, and infiltrative cardiomyopathies. HCM in children has its own section in this review, with possible risk factors that are distinct from those in adults; delayed enhancement in children may play a role in risk stratification in HCM. Finally, a number of teaching points for general cardiologists who recommend CMR for patients with HCM will be presented.

Multi-factor regulatory network and different clusters in hypertrophic obstructive cardiomyopathy

BACKGROUND

Practical biosignatures and thorough understanding of regulatory processes of hypertrophic obstructive cardiomyopathy (HOCM) are still lacking.

METHODS

Firstly, public data from GSE36961 and GSE89714 datasets of Gene Expression Omnibus (GEO), Gene database of NCBI (National Center of Biotechnology Information) and Online Mendelian Inheritance in Man (OMIM) database were merged into a candidate gene set of HOCM. Secondly, weighted gene co-expression network analysis (WGCNA) for the candidate gene set was carried out to determine premier co-expressed genes. Thirdly, significant regulators were found out by virtue of a multi-factor regulatory network of long non-coding RNAs (lncRNAs), messenger RNAs (mRNAs), microRNAs (miRNAs) and transcription factors (TFs) with molecule interreactions from starBase v2.0 database and TRRUST v2 database. Ultimately, HOCM unsupervised clustering and "tsne" dimensionality reduction was employed to gain hub genes, whose classification performance was evaluated by a multinomial model of lasso logistic regression analysis binded with receiver operating characteristic (ROC) curve.

RESULTS

Two HOCM remarkably-interrelated modules were from WGCNA, followed by the recognition of 32 crucial co-expressed genes. The multi-factor regulatory network disclosed 7 primary regulatory agents, containing lncRNAs (XIST, MALAT1, and H19), TFs (SPI1 and SP1) and miRNAs (hsa-miR-29b-39 and has-miR-29a-3p). Four clusters of HOCM and 4 hub genes (COMP, FMOD, AEBP1 and SULF1) significantly expressing in preceding four subtypes were obtained, while ROC curve demonstrated satisfactory performance of clustering and 4 genes.

CONCLUSIONS

Our consequences furnish valuable resource which may bring about prospective mechanistic and therapeutic anatomization in HOCM.

Correlations between cardiac troponin I and nonsustained ventricular tachycardia in hypertrophic obstructive cardiomyopathy

BACKGROUND

Nonsustained ventricular tachycardia (NSVT) is an independent risk factor for sudden cardiac death (SCD) in patients with hypertrophic obstructive cardiomyopathy (HOCM). However, data concerning the correlations of cardiac biomarkers and NSVT in HOCM are rather limited.

HYPOTHESIS

Our study aimed to investigate the associations between the occurrence of NSVT and circulating biomarkers representing myocardial injury (cardiac troponin I, cTnI), cardiac function (N-terminal pro-brain natriuretic peptide, NT-pro BNP), and inflammation (high-sensitivity C-reactive protein) in a large Chinese HOCM cohort.

METHODS

A total of 755 consecutive HOCM patients were recruited. Systematic cardiac evaluations and circulating biomarkers were examined routinely in all subjects under the clinically stable status. According to the results of 24-hour Holter monitoring, patients were divided into the NSVT group (n = 138) and the nonventricular tachycardia (non-VT) group (n = 617).

RESULTS

Compared with the non-VT group, circulating levels of both cTnI and NT-pro BNP elevated significantly in patients with positive NSVT episodes (P < .001). Multivariable analyses demonstrated that cTnI was independently associated with the presence of NSVT (OR = 1.675, 95% CI: 1.406-1.994, P < .001). Concentrations of cTnI increased progressively not only with the aggravation of ventricular arrhythmic events (P < .001), but also with the growing risk of SCD in HOCM patients (P < .001). Serum cTnI ≥ 0.0265 ng/mL indicated predictive value for the occurrence of NSVT in the HOCM cohort (area under the curve = 0.707, 95% CI: 0.660-0.754, P < .001).

CONCLUSIONS

Elevated cTnI was an independent determinant of NSVT, and it seemed to be valuable for assessing the clinical status of ventricular arrhythmias and the risk of SCD in patients with HOCM.

Zinc finger protein 91 loss induces cardiac hypertrophy through adenosine A1 receptor down-regulation under pressure overload status

The function of zfp91 is mainly studied in vitro, but there is no study in vivo. Accumulative data suggest that zfp91 may be an important gene to regulate all aspects of human response. However, there are no data to date about the function of zfp91 on cardiac homeostasis. Thus, we aimed to observe the role of zfp91 gene in mouse cardiomyocytes on myocardial homeostasis and related mechanisms under pressure overload. In the study, zfp91 mRNA and protein levels were significantly reduced in TAC-operated WT mice as compared with controls. Genetic ablation of zfp91 dramatically led to pathological cardiac dysfunction and hypertrophy after transverse aortic constriction (TAC). Adenosine A1 receptor (Adora1) mRNA and protein expressions were significantly down-regulated in the heart of zfp91-deletion mice with TAC. Zfp91 overexpression reversed isoproterenol-induced cardiomyocyte hypertrophy, which was abolished by selective Adora1 antagonist. Dual-luciferase reporter and ChIP-qPCR assays indicated that zfp91 acted on Adora1 promoter through its binding site. Last, Adora1 agonist rescued heart dysfunction and cardiac hypertrophy in zfp91 loss mice after TAC. Zfp91 may transcriptionally regulate Adora1 expression in the heart, which mainly maintained cardiac homeostasis under pressure overload status. It will provide a new approach to treat cardiac hypertrophy.

Non-diagnostic autopsy findings in sudden unexplained death victims

BACKGROUND

Several inherited cardiac diseases may lead to sudden cardiac death (SCD) a devastating event in the families. It is crucial to establish a post mortem diagnosis to facilitate relevant work-up and treatment of family members. Sudden unexplained death (SUD) victims constitute roughly one third of all SCD cases in Denmark.

METHODS

This was a single center, retrospective study investigating SUD cases. Victims who died unexplained due to suspected or confirmed cardiac disease were consecutively referred to a third line referral center established in 2005. All autopsy reports were investigated. Victims were divided into two groups: non-diagnostic cardiac findings and normal cardiac findings. None of the included victims had findings consistent with a diagnosis based on existing criteria.

RESULTS

In total, 99 SUD cases were referred. The mean age of the victims was 37 years (range 0-62 years, 75% males). A total of 14 (14%) victims had a cardiovascular diagnosis pre-mortem. Thirty-seven cases had normal cardiac findings and non-diagnostic cardiac findings were found in 62 cases (63%). The five most common findings included ventricular hypertrophy and/or enlarged heart (n = 35, 35%), coronary atheromatosis (n = 31, 31%), myocardial fibrosis (n = 19, 19%), dilated chambers (n = 7, 7%) and myocardial inflammation (n = 5, 5%).

CONCLUSION

One third of SUD victims had normal cardiac findings and non-diagnostic cardiac findings were seen in almost two thirds of the SUD victims. These non-diagnostic findings may be precursors or early markers for underlying structural cardiac disorders or may be innocent bystanders in some cases. Further studies and improved post-mortem examination methods are needed for optimization of diagnostics in SUD.

Hypertrophic Obstructive Cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is caused by mutations in a number of genes. Its prevalence is 0.2% to 0.6%.

METHODS

This review is based on publications retrieved by a selective literature search and on the authors' clinical experi- ence.

RESULTS

70% of patients with HCM suffer from the obstructive type of the condition, clinically characterized by highly dynamic and variable manifestations in the form of dyspnea, angina pectoris, and stress-dependent presyncope and syn- cope. Younger patients are at particular risk of sudden cardiac death; thus, all patients need not only symptomatic treatment, but also risk assessment, which can be difficult in individual cases. Left ventricular obstruction, which usually causes symptoms, is treated medically at first, with either a beta- blocker or verapamil. If medical treatment fails, two invasive treatments are available, surgical myectomy and percu- taneous septum ablation. Both of these require a high level of expertise. If performed successfully, they lead to sustained gradient reduction and clinical improvement. Septum ablation is associated with low perioperative and peri-interventional mortality but necessitates permanent pacemaker implantation in 10-20% of patients.

CONCLUSION

In the absence of evidence from randomized comparison trials, a suitable method of reducing the gradient should be determined by an HCM team in conjunction with each individual patient. Important criteria for decision-making include the anatomical findings and any accompanying illnesses.

[Modern genetic counselling : Practical aspects exemplified by hypertrophic cardiomyopathy]

Genetic counselling and subsequent molecular genetic testing should be performed in patients when an inherited monogenic form of heart disease is suspected. For the individual patient as well as for the (possibly asymptomatic) relatives, molecular diagnostics is important for an early diagnosis, (preventive) therapy and prognosis assessment. Using the example of hypertrophic cardiomyopathy (HCM), the most common monogenic form of structural heart disease, essential aspects of modern genetic counselling are elucidated. Specific examples of one case with a classical form of hypertrophic obstructive cardiomyopathy and one case of congenital HCM with Noonan's syndrome are discussed.

Disparities in the Diagnosis of Hypertrophic Obstructive Cardiomyopathy: A Narrative Review of Current Literature

Hypertrophic obstructive cardiomyopathy (HOCM) is a disorder of abnormal thickening of the myocardium that affects 0.2% of the population. HOCM is a frequently implicated cause of sudden cardiac death (SCD) in young athletes. In this manner, this condition has the capacity for tremendous emotional, social, financial, and medical burdens for families and communities across the country. Multiple factors including genetics and hormonal elements are believed to play a role in the development of this cardiomyopathy. HOCM is an autosomal dominant trait with variable expressivity. It is associated with several genetic changes in the myosin heavy chain genes. Current treatment includes optimization of cardiac risk factors and medical management with beta-adrenergic blockade with definitive treatment of surgical intervention to reduce cardiac workload. The demographic most likely to be diagnosed with HOCM based upon clinical registry data is Caucasian boys and men. However, a growing body of data supports increased prevalence in African American populations and percentages equal to, if not higher than, Caucasian males in Hispanic populations. Similarly, males of African American ethnicity that participate in basketball are the most likely demographic to be affected by HOCM based on the data available from the National Collegiate Athletic Association (NCAA). Further, though rates of diagnosis may be up to 1.5 times higher in males than in females, an increasing number of studies demonstrate an increased prevalence of HOCM in females, often presenting with worse symptoms and an increased incidence of disease progression. Similarly, data suggest that age of diagnosis is associated with various prognostic factors including annual mortality. In addition, consideration of the social determinants of health undoubtedly impacts the rate of diagnosis, access to care, and HOCM-related complications in underserved populations. Effective screening including auscultation and electrocardiography (EKG) with confirmatory echocardiography in these communities supports equitable surveillance and management of HOCM.

Glue septal ablation: A promising alternative to alcohol septal ablation

Hypertrophic cardiomyopathy (HCM) is defined as myocardial hypertrophy in the absence of another cardiac or systemic disease capable of producing the magnitude of present hypertrophy. In about 70% of patients with HCM, there is left ventricular outflow tract (LVOT) obstruction (LVOTO) and this is known as obstructive type of hypertrophic cardiomyopathy (HOCM). Cases refractory to medical treatment have had two options either surgical septal myectomy or alcohol septal ablation (ASA) to alleviate LVOT gradient. ASA may cause some life-threatening complications including conduction disturbances and complete heart block, hemodynamic compromise, ventricular arrhythmias, distant and massive myocardial necrosis. Glue septal ablation (GSA) is a promising technique for the treatment of HOCM. Glue seems to be superior to alcohol due to some intrinsic advantageous properties of glue such as immediate polymerization which prevents the leak into the left anterior descending coronary artery and it is particularly useful in patients with collaterals to the right coronary artery in whom alcohol ablation is contraindicated. In our experience, GSA is effective and also a safe technique without significant complications. GSA decreases LVOT gradient immediately after the procedure and this reduction persists during 12 months of follow-up. It improves New York Heart Association functional capacity and decrease interventricular septal wall thickness. Further studies are needed in order to assess the long-term efficacy and safety of this technique.

[Exercise training in the therapy of heart diseases: Current evidence and future options]

Exercise training has been firmly established as an additional therapeutic strategy in addition to pharmacological and interventional treatment in patients with cardiovascular disease. Benefits for quality of life as well as prognosis have been confirmed for cardiovascular risk factors, ischemic heart disease, after myocardial infarction, in heart failure with preserved as well as reduced ejection fraction, in atrial fibrillation and in patients after catheter-assisted aortic valve implantation (TAVI), with an implantable cardioverter defibrillator (ICD) or with left ventricular assist devices (VAD). Training programs have to be tailored according to the disease, stage of disease, comorbidities, age of the patient, medication as well as exercise capacity. For prescribing exercise mode and intensity, a maximum exercise test has to be performed. Ideally, this is accompanied by spirometry to assess maximum values such as maximum oxygen consumption. Training intensity will then be prescribed according to the optimal training range and maximum training intensity.

Percutaneous Septal Ablation in Hypertrophic Obstructive Cardiomyopathy: From Experiment to Standard of Care

Hypertrophic cardiomyopathy (HCM) is one of the more common hereditary cardiac conditions. According to presence or absence of outflow obstruction at rest or with provocation, a more common (about 60-70%) obstructive type of the disease (HOCM) has to be distinguished from the less common (30-40%) nonobstructive phenotype (HNCM). Symptoms include exercise limitation due to dyspnea, angina pectoris, palpitations, or dizziness; occasionally syncope or sudden cardiac death occurs. Correct diagnosis and risk stratification with respect to prophylactic ICD implantation are essential in HCM patient management. Drug therapy in symptomatic patients can be characterized as treatment of heart failure with preserved ejection fraction (HFpEF) in HNCM, while symptoms and the obstructive gradient in HOCM can be addressed with beta-blockers, disopyramide, or verapamil. After a short overview on etiology, natural history, and diagnostics in hypertrophic cardiomyopathy, this paper reviews the current treatment options for HOCM with a special focus on percutaneous septal ablation. Literature data and the own series of about 600 cases are discussed, suggesting a largely comparable outcome with respect to procedural mortality, clinical efficacy, and long-term outcome.

Hypertrophic cardiomyopathy mimicking acute anterior myocardial infarction associated with sudden cardiac death

Hypertrophic cardiomyopathy is the most common genetic disease of the heart. We report a rare case of hypertrophic obstructive cardiomyopathy mimicking an acute anterior myocardial infarction associated with sudden cardiac death. The patient presented with acute ST elevation myocardial infarction and significant elevation of cardiac enzymes. Cardiac catheterization showed some atherosclerotic coronary artery disease, without significant stenosis. Echocardiography showed left ventricular hypertrophy with a left ventricular outflow tract obstruction; the pressure gradient at rest was 20 mmHg and became severe with the Valsalva maneuver (100 mmHg). There was no family history of sudden cardiac death. Six days later, the patient suffered a syncope on his way to magnetic resonance imaging. He was successfully resuscitated by ventricular fibrillation.

The potential role of endogenous bacteriophages in controlling invading pathogens

Bacteriophages (phages) are omnipresent in our environment, and recent studies highlight their potential impact on the microbial world. Phages can also be present in mammalian organisms, including man (intestines, oral cavity, urine, sputum and serum). Data are available which suggest that those endogenous phages could play an important role in eliminating bacteria and regulating the body ecosystem. Furthermore, our most recent findings suggest that phages can exert immunosuppressive action in the gut, helping control local inflammatory and autoimmune reactions, and demonstrate anticancer activity. We hypothesize that phages could act in concert with the immune system in immunosurveillance against bacteria, viruses and cancer.