Clinical features of the dilated phase of hypertrophic cardiomyopathy in comparison with those of dilated cardiomyopathy

Influencing and prognostic factors of end-stage hypertrophic cardiomyopathy

AIMS

End-stage hypertrophic cardiomyopathy (ES-HCM) is a disease with severe complications and a poor prognosis. This study aimed to explore the influencing and prognostic factors of ES-HCM.

METHODS AND RESULTS

A total of 1282 patients with HCM who were hospitalized for the first time at Fujian Medical University Union Hospital between 1 January 2013 and 30 September 2021 were recorded. The patients with HCM and left ventricular ejection fraction (LVEF) < 50% were defined as having ES-HCM, and a control group (LVEF ≥ 50%) was generated from the collected medical records of HCM. The patients were matched in a ratio of 4:1 based on age and sex. Logistic regression analysis was used to determine the influencing factors of ES-HCM. Kaplan-Meier survival analysis was performed to analyse the clinical outcomes of ES-HCM patients. A total of 250 inpatients with HCM were enrolled in the study; 50 patients had ES-HCM, and 200 had HCM with LVEF ≥ 50%. The mean age of the patients at enrolment was 62.5 ± 10.3 years, and 215 patients (215/250, 86.0%) were male. The median follow-up time of the patients was 2.8 (1.4-5.4) years. The incidence of all-cause death and cardiovascular death in patients with ES-HCM was higher than those in patients with HCM and LVEF ≥ 50% (22/50 [44.0%] vs. 13/200 [6.5%]; 12/50 [24.0%] vs. 4/200 [2.0%], all P < 0.001). Multivariate logistic regression analysis showed that the influencing factors associated with ES-HCM included age at first symptom onset (odds ratio [OR] = 0.95, 95% CI [0.90, 1.00], P = 0.042), New York Heart Association (NYHA) class (OR = 7.73, 95% CI [2.93, 20.41], P < 0.001), heart rate (OR = 1.07, 95% CI [1.02, 1.12], P = 0.003), QRS duration (OR = 1.03, 95% CI [1.00, 1.05], P = 0.020), left ventricular end-diastolic diameter (LVEDD) (OR = 1.15, 95% CI [1.04, 1.28], P = 0.006), left atrial anteroposterior diameter (LAD) (OR = 1.13, 95% CI [1.03, 1.24], P = 0.012), and maximum left ventricular wall thickness (MLVWT) (OR = 0.80, 95% CI [0.68, 0.93], P = 0.005). Among the 50 patients with ES-HCM, NYHA class (P < 0.001) and heart rate (P = 0.017) were each associated with a higher likelihood and earlier occurrence of heart transplantation or all-cause mortality in univariate analyses.

CONCLUSIONS

The influencing factors for ES-HCM included the age at first symptom onset, NYHA class, heart rate, QRS duration, LVEDD, LAD, and MLVWT. Both NYHA class and heart rate were related to the prognosis of ES-HCM.

Metabolic remodeling and calcium handling abnormality in induced pluripotent stem cell-derived cardiomyocytes in dilated phase of hypertrophic cardiomyopathy with MYBPC3 frameshift mutation

Hypertrophic cardiomyopathy (HCM) is an inherited disorder characterized by left ventricular hypertrophy and diastolic dysfunction, and increases the risk of arrhythmias and heart failure. Some patients with HCM develop a dilated phase of hypertrophic cardiomyopathy (D-HCM) and have poor prognosis; however, its pathogenesis is unclear and few pathological models exist. This study established disease-specific human induced pluripotent stem cells (iPSCs) from a patient with D-HCM harboring a mutation in MYBPC3 (c.1377delC), a common causative gene of HCM, and investigated the associated pathophysiological mechanisms using disease-specific iPSC-derived cardiomyocytes (iPSC-CMs). We confirmed the expression of pluripotent markers and the ability to differentiate into three germ layers in D-HCM patient-derived iPSCs (D-HCM iPSCs). D-HCM iPSC-CMs exhibited disrupted myocardial sarcomere structures and an increased number of damaged mitochondria. Ca2+ imaging showed increased abnormal Ca2+ signaling and prolonged decay time in D-HCM iPSC-CMs. Cell metabolic analysis revealed increased basal respiration, maximal respiration, and spare-respiratory capacity in D-HCM iPSC-CMs. RNA sequencing also showed an increased expression of mitochondrial electron transport system-related genes. D-HCM iPSC-CMs showed abnormal Ca2+ handling and hypermetabolic state, similar to that previously reported for HCM patient-derived iPSC-CMs. Although further studies are required, this is expected to be a useful pathological model for D-HCM.

2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy.

METHODS

A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy.

METHODS

A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

Left Atrial Appendage Closure with the Watchman FLX System in a Patient with Hypertrophic Cardiomyopathy on Dialysis for End-stage Renal Failure

Patients with hypertrophic cardiomyopathy (HCM) often have atrial fibrillation, and empiric anticoagulation is recommended in these patients, regardless of other risk factors. However, anticoagulation is not recommended for patients who require hemodialysis (HD) because of the high bleeding risk. We herein report a case of left atrial appendage closure (LAAC) using the Watchman FLX system for a dilated phase HCM patient complicated by persistent atrial fibrillation and requiring HD. LAAC with the Watchman FLX system may be an alternative to antithrombotic medications in patients with dilated HCM complicated by atrial fibrillation and requiring HD.

Mitochondrial Protein Homeostasis and Cardiomyopathy

Human mitochondrial disorders impact tissues with high energetic demands and can be associated with cardiac muscle disease (cardiomyopathy) and early mortality. However, the mechanistic link between mitochondrial disease and the development of cardiomyopathy is frequently unclear. In addition, there is often marked phenotypic heterogeneity between patients, even between those with the same genetic variant, which is also not well understood. Several of the mitochondrial cardiomyopathies are related to defects in the maintenance of mitochondrial protein homeostasis, or proteostasis. This essential process involves the importing, sorting, folding and degradation of preproteins into fully functional mature structures inside mitochondria. Disrupted mitochondrial proteostasis interferes with mitochondrial energetics and ATP production, which can directly impact cardiac function. An inability to maintain proteostasis can result in mitochondrial dysfunction and subsequent mitophagy or even apoptosis. We review the known mitochondrial diseases that have been associated with cardiomyopathy and which arise from mutations in genes that are important for mitochondrial proteostasis. Genes discussed include DnaJ heat shock protein family member C19 (DNAJC19), mitochondrial import inner membrane translocase subunit TIM16 (MAGMAS), translocase of the inner mitochondrial membrane 50 (TIMM50), mitochondrial intermediate peptidase (MIPEP), X-prolyl-aminopeptidase 3 (XPNPEP3), HtraA serine peptidase 2 (HTRA2), caseinolytic mitochondrial peptidase chaperone subunit B (CLPB) and heat shock 60-kD protein 1 (HSPD1). The identification and description of disorders with a shared mechanism of disease may provide further insights into the disease process and assist with the identification of potential therapeutics.

MEF2 in cardiac hypertrophy in response to hypertension

Hypertension is a globally prevalent pathological condition and an underlying risk factor for the development of cardiac hypertrophy leading to heart failure. Myocyte enhancer factor 2 (Mef2) has been identified as one of the primary effectors of morphological changes in the hypertensive heart, as part of a complex network of molecular signaling controlling cardiac gene expression. Experimental chronic pressure-overload models that mimic hypertension in the mammalian heart lead to the activation of various pathological mechanisms that result in structural changes leading to debilitating cardiac hypertrophy and ultimately heart failure. The purpose here is to survey the literature implicating Mef2 in hypertension induced cardiac hypertrophy, towards illuminating points of interest for understanding and potentially treating heart failure.

Implantation of ventricular assist devices in hypertrophic cardiomyopathy with left ventricular systolic dysfunction

AIMS

The outcomes of patients with hypertrophic cardiomyopathy with left ventricular systolic dysfunction (HCM-LVSD) undergoing left ventricular assist device (LVAD) implantation remain unclear. We retrospectively evaluated the clinical impact of LVAD implantation on clinical outcomes, including haemodynamics and brain natriuretic peptide (BNP) levels, in patients with HCM-LVSD, in comparison with those with dilated cardiomyopathy (DCM).

METHODS AND RESULTS

In this retrospective, single-centre, observational study conducted in Japan, the medical records of patients who underwent LVAD implantation in the National Cerebral and Cardiovascular Center between 2011 and 2020 were reviewed. We enrolled 96 patients with DCM (average age: 43.5 years; 73 men) and 24 patients with HCM-LVSD (average age: 48.3 years; 16 men). The HCM-LVSD group had smaller left ventricles with thicker ventricular walls than the DCM group, which became more prominent after LVAD implantation. Preoperatively, BNP values were comparable between both groups; however, 3 months post-implantation, they were significantly higher in the HCM-LVSD group. Pulmonary artery pulsatility index, right ventricular stroke work index, and cardiac index were lower, and right atrial pressure was higher, in the HCM-LVSD group, suggesting subclinical impairment of right ventricular function. The HCM-LVSD group demonstrated equivalent outcomes, including overall survival, cerebrovascular accidents, right ventricular failure, LVAD-related infections, arrhythmia, and aortic insufficiency, post-implantation.

CONCLUSIONS

Despite a decreased right ventricular function with higher BNP values, patients with HCM-LVSD and DCM showed comparable outcomes post-LVAD implantation.

ELAC2/RNaseZ-linked cardiac hypertrophy in Drosophila melanogaster

A severe form of infantile cardiomyopathy (CM) has been linked to mutations in ELAC2, a highly conserved human gene. It encodes Zinc phosphodiesterase ELAC protein 2 (ELAC2), which plays an essential role in the production of mature tRNAs. To establish a causal connection between ELAC2 variants and CM, here we used the Drosophila melanogaster model organism, which carries the ELAC2 homolog RNaseZ. Even though RNaseZ and ELAC2 have diverged in some of their biological functions, our study demonstrates the use of the fly model to study the mechanism of ELAC2-related pathology. We established transgenic lines harboring RNaseZ with CM-linked mutations in the background of endogenous RNaseZ knockout. Importantly, we found that the phenotype of these flies is consistent with the pathological features in human patients. Specifically, expression of CM-linked variants in flies caused heart hypertrophy and led to reduction in cardiac contractility associated with a rare form of CM. This study provides first experimental evidence for the pathogenicity of CM-causing mutations in the ELAC2 protein, and the foundation to improve our understanding and diagnosis of this rare infantile disease.

This article has an associated First Person interview with the first author of the paper.

Summary: A newly established Drosophila model recapitulates key features of human heart pathology linked to mutations in ELAC2, thus providing experimental evidence of the pathogenicity of ELAC2 variants.

Clinical Outcomes of Autologous Stem Cell-Patch Implantation for Patients With Heart Failure With Nonischemic Dilated Cardiomyopathy

Background

Clinical effectiveness of autologous skeletal cell‐patch implantation for nonischemic dilated cardiomyopathy has not been clearly elucidated in clinical settings. This clinical study aimed to determine the feasibility, safety, therapeutic efficacy, and the predictor of responders of this treatment in patients with nonischemic dilated cardiomyopathy.

Methods and Results

Twenty‐four nonischemic dilated cardiomyopathy patients with left ventricular ejection fraction <35% on optimal medical therapy were enrolled. Autologous cell patches were implanted over the surface of the left ventricle through left minithoracotomy without procedure‐related complications and lethal arrhythmia. We identified 13 responders and 11 nonresponders using the combined indicator of a major cardiac adverse event and incidence of heart failure event. In the responders, symptoms, exercise capacity, and cardiac performance were improved postoperatively (New York Heart Association class II 7 [54%] and III 6 [46%] to New York Heart Association class II 12 [92%] and I 1 [8%], P<0.05, 6‐minute walk test; 471 m [370–541 m] to 525 m [425–555 m], P<0.05, left ventricular stroke work index; 31.1 g·m²·beat [22.7–35.5 g·m²·beat] to 32.8 g·m²·beat [28–38.5 g·m²·beat], P=0.21). However, such improvement was not observed in the nonresponders. In responders, the actuarial survival rate was 90.9±8.7% at 5 years, which was superior to the estimated survival rate of 70.9±5.4% using the Seattle Heart Failure Model. However, they were similar in nonresponders (47.7±21.6% and 56.3±8.1%, respectively). Multivariate regression model with B‐type natriuretic peptide, pulmonary capillary wedge pressure, and expression of histone H3K4me3 (H3 lysine 4 trimethylation) strongly predicted the responder of this treatment (B‐type natriuretic peptide: odds ratio [OR], 0.96; pulmonary capillary wedge pressure: ​OR, 0.58; H3K4me3: OR, 1.35, receiver operating characteristic–area under the curve, 0.96, P<0.001).

Conclusions

This clinical trial demonstrated that autologous skeletal stem cell–patch implantation might promise functional recovery and good clinical outcome in selected patients with nonischemic dilated cardiomyopathy, in addition to safety and feasibility.

Registration

URL: http://www.umin.ac.jp/english/. Unique identifiers: UMIN000003273, UMIN0000012906 and UMIN000015892.

Sex Differences, Genetic and Environmental Influences on Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) is characterized by dilatation of the left ventricle and impaired systolic function and is the second most common cause of heart failure after coronary heart disease. The etiology of DCM is diverse including genetic pathogenic variants, infection, inflammation, autoimmune diseases, exposure to chemicals/toxins as well as endocrine and neuromuscular causes. DCM is inherited in 20–50% of cases where more than 30 genes have been implicated in the development of DCM with pathogenic variants in TTN (Titin) most frequently associated with disease. Even though male sex is a risk factor for heart failure, few studies have examined sex differences in the pathogenesis of DCM. We searched the literature for studies examining idiopathic or familial/genetic DCM that reported data by sex in order to determine the sex ratio of disease. We found 31 studies that reported data by sex for non-genetic DCM with an average overall sex ratio of 2.5:1 male to female and 7 studies for familial/genetic DCM with an overall average sex ratio of 1.7:1 male to female. No manuscripts that we found had more females than males in their studies. We describe basic and clinical research findings that may explain the increase in DCM in males over females based on sex differences in basic physiology and the immune and fibrotic response to damage caused by mutations, infections, chemotherapy agents and autoimmune responses.

Elevation of high-sensitivity cardiac troponin T and left ventricular remodelling in hypertrophic cardiomyopathy

Aims

Hypertrophic cardiomyopathy (HCM) is generally associated with mild disability and normal life expectancy. On the other hand, once the end‐stage phase of HCM characterized by left ventricular (LV) ejection fraction < 50% is established, patients with this subtype have a poor prognosis. This study clarifies the clinical parameters associated with progression to end‐stage HCM.

Methods and results

We retrospectively studied 157 HCM patients (age 59.9 ± 14.2 years, 104 men) with preserved LV systolic function in whom subsequent echocardiographic data were obtained for a period of >1 year. HCM progressed to end‐stage HCM in 13 patients (8.3%) of the 157 patients during a mean follow‐up period of 6.3 ± 2.8 years. Compared with patients who did not reach end‐stage HCM at the last evaluation, patients with progression to the end‐stage phase had lower ejection fraction, larger LV size, more enlarged left atrial diameter, longer follow‐up period, and higher frequency of an elevated concentration of high‐sensitivity cardiac troponin T (hs‐cTnT; >0.014 ng/mL) at registration. Multivariate analysis revealed that elevated hs‐cTnT was a significant predictor independent of lower LV ejection fraction for progression to end‐stage HCM. Furthermore, in patients with elevated hs‐cTnT levels, LV ejection fraction became significantly lower, LV end‐diastolic diameter increased, and LV wall thickness decreased during the follow‐up period, whereas those parameters did not change in the normal hs‐cTnT group.

Conclusions

In patients with HCM, an elevated hs‐cTnT was associated with progression of LV remodelling, and this biomarker can be useful for predicting progression to the end‐stage phase.

Characterisation of the developing heart in a pressure overloaded model utilising RNA sequencing to direct functional analysis

Cardiogenesis is influenced by both environmental and genetic factors, with blood flow playing a critical role in cardiac remodelling. Perturbation of any of these factors could lead to abnormal heart development and hence the formation of congenital heart defects. Although abnormal blood flow has been associated with a number of heart defects, the effects of abnormal pressure load on the developing heart gene expression profile have to date not clearly been defined. To determine the heart transcriptional response to haemodynamic alteration during development, outflow tract (OFT) banding was employed in the chick embryo at Hamburger and Hamilton stage (HH) 21. Stereological and expression studies, including the use of global expression analysis by RNA sequencing with an optimised procedure for effective globin depletion, were subsequently performed on HH29 OFT-banded hearts and compared with sham control hearts, with further targeted expression investigations at HH35. The OFT-banded hearts were found to have an abnormal morphology with a rounded appearance and left-sided dilation in comparison with controls. Internal analysis showed they typically had a ventricular septal defect and reductions in the myocardial wall and trabeculae, with an increase in the lumen on the left side of the heart. There was also a significant reduction in apoptosis. The differentially expressed genes were found to be predominately involved in contraction, metabolism, apoptosis and neural development, suggesting a cardioprotective mechanism had been induced. Therefore, altered haemodynamics during development leads to left-sided dilation and differential expression of genes that may be associated with stress and maintaining cardiac output.

Modes of death and clinical outcomes in adult patients with hypertrophic cardiomyopathy in Thailand

Background

There are limited data about modes of death and major adverse cardiovascular events (MACEs) in patients with hypertrophic cardiomyopathy (HCM) in South East Asian population. The aim of the study was to examine modes of death and clinical outcomes in Thai patients with HCM.

Methods

Between January 1, 2009 and December 31, 2013, 166 consecutive patients with HCM diagnosed in our institution were evaluated. Five patients were excluded because of non-Thai ethnic groups (n = 3) and diagnosis of myocardial infarction at initial presentation documented by coronary angiography (n = 2). The final study population consisted of 161 patients with HCM. HCM-related deaths included: (1) sudden cardiac death (SCD) – death due to sudden cardiac arrest or unexpected sudden death; (2) heart failure – death due to refractory heart failure; or (3) stroke - death due to embolic stroke associated with atrial fibrillation. MACEs included: (1) SCD, sudden unexpected aborted cardiac arrest, fatal, or nonfatal ventricular arrhythmia (ventricular fibrillation or sustained ventricular tachycardia); (2) heart failure (fatal or non-fatal), or heart transplantation; or (3) stroke - fatal or non-fatal embolic stroke associated with atrial fibrillation.

Results

One hundred and sixty-one Thai patients with HCM (age 66 ± 16 years, 58% female) were enrolled. Forty-two patients (26%) died over a median follow-up period of 6.8 years including 25 patients (16%) with HCM-related deaths (2%/year). The HCM-related deaths included: heart failure (52% of HCM-related deaths; n = 13), SCD (44% of HCM-related deaths; n = 11), and stroke (4% of HCM-related deaths, n = 1). The SCDs occurred in 6.8% of patients (1%/year). Eighty-four major MACEs occurred in 65 patients (41, 5%/year). The MACEs included: 40 heart failures in which 2 patients underwent heart transplants; 22 SCDs and nonfatal ventricular arrhythmias; and 22 fatal or nonfatal strokes.

Conclusions

The most common mode of death in adult patients with HCM in Thailand was heart failure followed by SCD. About one-third of the patients experiencing heart failure died during the 6.8 years of follow-up. SCDs occurred in 7% of patients (1%/year), predominantly in the fourth decade or later.

Validation of the 2014 European Society of Cardiology Sudden Cardiac Death Risk Prediction Model Among Various Phenotypes in Japanese Patients With Hypertrophic Cardiomyopathy

Risk stratification for sudden cardiac death (SCD) is essential in the management of hypertrophic cardiomyopathy (HC). The 2014 European Society of Cardiology SCD risk prediction model (Risk-SCD) is a novel risk scoring system; however, whether it can be applied to Japanese HC and its usefulness among various HC phenotypes remain unclear. The aim of this study was to validate the Risk-SCD model in Japanese HC, and to evaluate its usefulness among various HC phenotypes. We studied 370 consecutive Japanese HC patients evaluated for primary SCD prevention at our tertiary referral center. The Risk-SCD model was validated in 289 HC patients with ejection fraction (EF) ≥50% (including left ventricular outflow tract obstruction [LVOTO], mid ventricular obstruction [MVO], apical hypertrophy, and nonobstructive phenotypes), and 81 end-stage HC patients (EF <50%). The end point of the study was SCD or an equivalent event (appropriate implantable cardioverter defibrillator therapy or successful resuscitation after cardiac arrest). Thirty-one SCD events were observed during a median follow-up of 5.2 (interquartile range 3.5 to 6.9) years. The Risk-SCD model showed improved risk prediction in HC with EF ≥50% compared with the previous 2011 American College of Cardiology Foundation/American Heart Association and 2003 American College of Cardiology/European Society of Cardiology guideline approaches (number needed to treat = 3.8 at Risk-SCD >6%) regardless of phenotypes; LVOTO, MVO, apical, and nonobstructive, but misclassified SCD risk in end-stage HC. In the current external validation of the Risk-SCD model in Japanese HC, the model improved SCD prediction compared with previous approaches, and was also shown to be useful in LVOTO, MVO, apical, and nonobstructive phenotypes.

Patients' Characteristics and Clinical Course of Hypertrophic Cardiomyopathy in a Regional Japanese Cohort - Results From Kochi RYOMA Study

BACKGROUND

There have been few studies on the clinical course of hypertrophic cardiomyopathy (HCM) in a community-based patient cohort in Japan.Methods and Results:In 2004, we established a cardiomyopathy registration network in Kochi Prefecture (the Kochi RYOMA study) that consisted of 9 hospitals, and finally, 293 patients with HCM were followed. The ages at registration and at diagnosis were 63±14 and 56±16 years, respectively, and 197 patients (67%) were male. HCM-related deaths occurred in 23 patients during a mean follow-up period of 6.1±3.2 years. The HCM-related 5-year survival rate was 94%. In addition, a total of 77 cardiovascular events that were clinically severe occurred in 70 patients, and the HCM-related 5-year event-free rate was 80%. Multivariate Cox proportional hazards model analysis showed that the presence of NYHA class III at registration was a significant predictor of HCM-related deaths and that the presence of atrial fibrillation, lower fractional shortening and presence of left ventricular outflow tract obstruction in addition to NYHA class III were significant predictors of cardiovascular events.

CONCLUSIONS

In our unselected registry in an aged Japanese community, HCM mortality was favorable, but one-fifth of the patients commonly suffered from HCM-related adverse cardiovascular events during the 5-year follow-up period. Careful management of HCM patients is needed, particularly for those with the above-mentioned clinical determinants.

Multiple Species Comparison of Cardiac Troponin T and Dystrophin: Unravelling the DNA behind Dilated Cardiomyopathy

Animals have frequently been used as models for human disorders and mutations. Following advances in genetic testing and treatment options, and the decreasing cost of these technologies in the clinic, mutations in both companion and commercial animals are now being investigated. A recent review highlighted the genes associated with both human and non-human dilated cardiomyopathy. Cardiac troponin T and dystrophin were observed to be associated with both human and turkey (troponin T) and canine (dystrophin) dilated cardiomyopathies. This review gives an overview of the work carried out in cardiac troponin T and dystrophin to date in both human and animal dilated cardiomyopathy.

Clinical outcome of cardiac resynchronization therapy in dilated-phase hypertrophic cardiomyopathy

BACKGROUNDS

Clinical trials have demonstrated that cardiac resynchronization therapy (CRT) is effective in patients with "non-ischemic cardiomyopathy". However, patients with dilated-phase hypertrophic cardiomyopathy (DHCM) have been generally excluded from such trials. We aimed to compare the clinical outcome of CRT in patients with DHCM, idiopathic dilated cardiomyopathy (IDCM), or ischemic cardiomyopathy (ICM).

METHODS

A total of 312 consecutive patients (DHCM: n = 16; IDCM: n = 231; ICM: n = 65) undergoing CRT in Fuwai hospital were studied respectively. Response to CRT was defined as reduction in left ventricular end-systolic volume (LVESV) ≥ 15% at 6-month follow-up.

RESULTS

Compared with DHCM, IDCM was associated with a lower total mortality (HR: 0.35, 95% CI: 0.13-0.90), cardiac mortality (HR: 0.29; 95% CI: 0.11-0.77), and total mortality or heart failure (HF) hospitalizations (HR: 0.34, 95% CI: 0.17-0.69), independent of known confounders. Compared with DHCM, the total mortality, cardiac mortality and total mortality or HF hospitalizations favored ICM but were not statistically significant (HR: 0.59, 95% CI: 0.22-1.61; HR: 0.59, 95% CI: 0.21-1.63; HR: 0.54, 95% CI: 0.26-1.15; respectively). Response rate to CRT was lower in the DHCM group than the other two groups although the differences didn't reach statistical significance.

CONCLUSIONS

Compared with IDCM, DHCM was associated with a worse outcome after CRT. The clinical outcome of DHCM patients receiving CRT was similar to or even worse than that of ICM patients. These indicate that DHCM behaves very differently after CRT.

Clinical Characteristics and Long-Term Outcomes of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) has various morphological and clinical features. A decade has passed since the previous survey of the epidemiological and clinical characteristics of Japanese HCM patients. The Aichi Hypertrophic Cardiomyopathy (AHC) Registry is based on a prospective multicenter observational study of HCM patients. The clinical characteristics of 42 ambulant HCM patients followed up for up to 5 years were investigated. The primary endpoint was major adverse cardiac events (MACE), defined as death, non-fatal stroke, admission due to congestive heart failure (CHF), or episodes of sustained ventricular tachycardia/fibrillation. The MACE-free survival during the 5-year follow-up period was 76% according to Kaplan-Meier analysis. HCM-related death occurred in 3 (7%) patients and SCD occurred in 2 (5%) patients. Additionally, 3 (7%) patients were admitted to the hospital due to CHF. Meanwhile, sustained VT was detected in one (2%) of the patients who received ICD implantation and subsequently terminated with antitachycardia pacing using an ICD. The patients with HCM exhibiting left ventricular outflow obstruction (HOCM) had a slightly lower MACE-free survival rate than those with neither HOCM nor dilated-HCM (dHCM) (71% versus 81%, log-rank P = 0.581). Furthermore, the patients with dHCM demonstrated a significantly lower MACE-free survival rate than those with neither HOCM nor dHCM (33% versus 81%, log-rank P = 0.029). In the AHC Registry targeting current Japanese HCM patients, we demonstrated that many HCM patients continue to suffer from MACE despite the development of various treatments for HCM.

Morphologic features of the recipient heart in patients having cardiac transplantation and analysis of the congruence or incongruence between the clinical and morphologic diagnoses

Cardiac transplantation (CT) has been one of the great medical advances of the last nearly 50 years. We studied the explanted hearts of 314 patients having CT at Baylor University Medical Center Dallas from 1993 to 2012, and compared the morphologic diagnoses to the clinical diagnoses before CT. Among the 314 patients the morphologic and clinical diagnoses were congruent in 272 (87%) and incongruent in 42 (13%). Most of the incongruity occurred among the 166 patients with non-ischemic cardiomyopathy (non-IC) (36/166 [22%]), and of that group the major incongruity occurred among the patients with hypertrophic cardiomyopathy (7/17 [41%]), non-compaction left ventricular cardiomyopathy (NCLVC) (3/3 [100%]), mononuclear myocarditis (3/3 [100%]), arrhythmogenic right ventricular cardiomyopathy (ARVC) (4/4 [100%]), and cardiac sarcoidosis (8/8 [100%]). The phrase "non-IC" is a general term that includes several subsets of cardiac diseases and simply means "insignificant narrowing of 1 or more of the epicardial coronary arteries," but it does not specify the specific cause of the heart failure leading to CT. A number of cardiac illustrations are provided to demonstrate the morphologic variability occurring among the patients with IC and non-IC.

Advances in medical treatment of hypertrophic cardiomyopathy

We reviewed the natural history of patients with hypertrophic cardiomyopathy (HCM). The effect of medical treatments on natural history, left ventricular (LV) functions and LV remodeling was also evaluated. Sudden cardiac death and end-stage heart failure are the most serious complications of HCM. Age <30 years and a family history of sudden premature death are risk factors for sudden cardiac death in HCM patients. End-stage heart failure is not a specific additional phenomenon observed in patients with HCM, but is the natural course of the disease in most of those patients. After the occurrence of heart failure, the progression to cardiac death is very rapid. Young age at diagnosis, a family history of HCM, and greater wall thickness are associated with a greater likelihood of developing end-stage heart failure. Neither beta-blockers nor calcium antagonists can prevent this transition. The class Ia antiarrhythmic drugs, disopyramide and cibenzoline are useful for the reduction of LV pressure gradient. Unlike disopyramide, cibenzoline has little anticholinergic activity; therefore, this drug can be easily adapted to long-term use. In addition to the reduction in LV pressure gradient, cibenzoline can improve LV diastolic dysfunction, and induce regression of LV hypertrophy in patients with HCM. A decrease in intracellular Ca(2+) concentration through the activation of the Na(+)/Ca(2+) exchanger associated with cibenzoline therapy is likely to be closely related with the improvement in HCM-related disorders. It is possible that cibenzoline can prevent the progression from typical HCM to end-stage heart failure.

Clinical characteristics and outcomes of dilated phase of hypertrophic cardiomyopathy: report from the registry data in Japan

BACKGROUND

A subset of patients with hypertrophic cardiomyopathy (HCM) has been reported to progress into dilated-HCM (D-HCM), characterized by left ventricular (LV) systolic dysfunction and cavity dilatation, resembling idiopathic dilated cardiomyopathy (DCM). We compared the characteristics, treatments, and outcomes in patients with heart failure (HF) due to D-HCM vs. DCM by using national registry data in Japan.

METHODS AND RESULTS

The Japanese Cardiac Registry of Heart Failure in Cardiology (JCARE-CARD) is a prospective observational study of patients hospitalized due to worsening HF with an average of 2.2 years of follow-up. Patients with D-HCM (n=41) were more likely to be male, have prior stroke, atrial fibrillation, and sustained ventricular tachycardia or ventricular fibrillation compared with DCM (n=486). Echocardiography demonstrated that D-HCM patients had smaller LV end-systolic diameter, higher ejection fraction, and greater wall thickness. Treatments for HF including angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, β-blocker, and spironolactone were similar between groups except for higher use of amiodarone, warfarin, and implantable cardioverter-defibrillator for D-HCM. Mortality was significantly higher in patients with D-HCM (29.7% vs. 14.4%; p<0.05). Sudden death tended to be higher also in D-HCM (8.1% vs. 2.6%; p=0.06), which, however, did not reach statistical significance.

CONCLUSIONS

HF patients with D-HCM had higher mortality risk than those with DCM. Effective management strategies are critically needed to be established for D-HCM.

Dilated phase of hypertrophic cardiomyopathy caused by two different sarcomere mutations, treated with surgical left ventricular reconstruction and cardiac resynchronization therapy with a defibrillator

We herein report the case of a 61-year-old woman with dilated phase of hypertrophic cardiomyopathy (D-HCM) who had been diagnosed with HCM 17 years previously. On admission, her left ventricle (LV) had marked dilation, dyssynchrony with diffuse severe hypokinesis, and ventricular tachycardia. She had two mutations in the cardiac myosin binding protein-C gene, which were suspected to be the causes of the D-HCM. We performed LV reconstruction surgery and cardiac resynchronization therapy with a defibrillator for her drug-resistant severe heart failure. After surgery, her New York Heart Association class dramatically improved, and she has not been re-hospitalized since these treatments.