Prevalence and etiology of idiopathic dilated cardiomyopathy (summary of a National Heart, Lung, and Blood Institute workshop

Plasma tissue inhibitor of matrix metalloproteinase-1 (TIMP-1): an independent predictor of poor response to cardiac resynchronization therapy

Aims

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) play a role in left ventricular structural remodelling. The aim of our study was to analyse MMP-2 and TIMP-1 levels as predictors of poor response to cardiac resynchronization therapy (CRT).

Methods and results

A cohort of 42 CRT patients from our centre was prospectively evaluated at baseline and after 12-month follow-up. MMP-2 and TIMP-1 assays were performed prior to CRT implant. Cardiac resynchronization therapy responders were defined as patients who survived, were not transplanted, and increased their basal 6 min walking distance test (6MWDT) by ≥10% or improved their NYHA functional class. Overall, 25 patients (60%) were classed as responders. At 12-month follow-up, six patients (14.2%) had died and one (2.4%) patient had been transplanted. Compared with responders, non-responders had higher levels of TIMP-1 (277 ± 59 vs. 216 ± 46 ng/mL, P = 0.001), MMP-2 (325 ± 115 vs. 258 ± 56 ng/mL, P = 0.02), and creatinine (1.76 ± 0.8 vs. 1.25 ± 0.3 mg/dL, P = 0.01). In a multivariate analysis, TIMP-1 was the only independent predictor of non-response to CRT [OR 0.97, 95% (CI 0.96–0.99) P = 0.005]. TIMP-1≥248 ng/mL predicted non-response with 71% sensitivity and 72% specificity.

Conclusion

TIMP-1 is an independent predictor of non-response in patients treated with CRT.

Nexilin mutations destabilize cardiac Z-disks and lead to dilated cardiomyopathy

Z-disks, the mechanical integration sites of heart and skeletal muscle cells, link anchorage of myofilaments to force reception and processing. The key molecules that enable the Z-disk to persistently withstand the extreme mechanical forces during muscle contraction have not yet been identified. Here we isolated nexilin (encoded by NEXN) as a novel Z-disk protein. Loss of nexilin in zebrafish led to perturbed Z-disk stability and heart failure. To evaluate the role of nexilin in human heart failure, we performed a genetic association study on individuals with dilated cardiomyopathy and found several mutations in NEXN associated with the disease. Nexilin mutation carriers showed the same cardiac Z-disk pathology as observed in nexilin-deficient zebrafish. Expression in zebrafish of nexilin proteins encoded by NEXN mutant alleles induced Z-disk damage and heart failure, demonstrating a dominant-negative effect and confirming the disease-causing nature of these mutations. Increasing mechanical strain aggravated Z-disk damage in nexilin-deficient skeletal muscle, implying a unique role of nexilin in protecting Z-disks from mechanical trauma.

Short-term mechanical unloading and reverse remodeling of failing hearts in children

BACKGROUND

Mechanical support using a left ventricular assist device (LVAD) can lead to functional recovery of the myocardium in patients with end-stage heart failure (HF). Molecular remodeling, cytoskeletal disruption, and apoptosis activation are associated with abnormal gene expression in the failing ventricular myocardium of HF subjects and can normalize in response to medium- and long-term mechanical unloading in adults. However, there is little knowledge of the changes in gene expression after short-term mechanical support in children with HF.

METHODS

We evaluated left ventricular biopsies from 4 children with HF. The children had implantation of a continuous- or a pulsatile-flow LVAD for 8 to 16 days before undergoing heart transplantation. At the time of LVAD insertion and removal, we performed quantitative real-time polymerase chain reaction (QPCR) to study the expression of 326 genes encoding for structural, transcriptional, and signaling pathways proteins, and immunoblot analysis on dystrophin and apoptotic factors.

RESULTS

Short-term LVAD therapy significantly decreased brain natriuretic peptide (BNP) levels from pre-LVAD (3,584.5 +/- 378.3 pg/ml [95% CI]) to post-LVAD (447.5 +/- 52.7 pg/ml [95% CI]) in 2 patients in whom comparative BNP measurements were available. In addition, short-term LVAD therapy reduced HF and apoptosis markers, whereas it upregulated structural proteins, including dystrophin, as well as pro-hypertrophic and pro-inotropic markers. Furthermore, LVAD therapy normalized expression of genes involved in calcium homeostasis, cell growth, and differentiation.

CONCLUSIONS

Our pilot study suggests that even short-term LVAD therapy in children with severe HF can reverse molecular remodeling. This favorable effect should be taken into consideration in eligible children with significant ventricular dysfunction.

Therapeutic effect of {beta}-adrenoceptor blockers using a mouse model of dilated cardiomyopathy with a troponin mutation

AIMS

Extensive clinical studies have demonstrated that beta-adrenoceptor blocking agents (beta-blockers) are beneficial in the treatment of chronic heart failure, which is due to various aetiologies, including idiopathic dilated cardiomyopathy (DCM) and ischaemic heart disease. However, little is known about the therapeutic efficacy of beta-blockers in the treatment of the inherited form of DCM, of which causative mutations have recently been identified in various genes, including those encoding cardiac sarcomeric proteins. Using a mouse model of inherited DCM with a troponin mutation, we aim to study the treatment benefits of beta-blockers.

METHODS AND RESULTS

Three different types of beta-blockers, carvedilol, metoprolol, and atenolol, were orally administered to a knock-in mouse model of inherited DCM with a deletion mutation DeltaK210 in the cardiac troponin T gene (TNNT2). Therapeutic effects were examined on the basis of survival and myocardial remodelling. The lipophilic beta(1)-selective beta-blocker metoprolol was found to prevent cardiac dysfunction and remodelling and extend the survival of knock-in mice. Conversely, both the non-selective beta-blocker carvedilol and the hydrophilic beta(1)-selective beta-blocker atenolol had no beneficial effects on survival and myocardial remodelling in this mouse model of inherited DCM.

CONCLUSION

The highly lipophilic beta(1)-selective beta-blocker metoprolol, known to prevent ventricular fibrillation via central nervous system-mediated vagal activation, may be especially beneficial to DCM patients showing a family history of frequent sudden cardiac death, such as those with a deletion mutation DeltaK210 in the TNNT2 gene.

Creatine kinase isoforms as circulating markers of deterioration in idiopathic dilated cardiomyopathy

BACKGROUND

A proportion of patients with dilated cardiomyopathy (DCM) may have ongoing myocardial damage secondary to viral or immune mediated myocardial inflammation.

HYPOTHESIS

The prognostic determinants identify patients with decreased survival but do not provide a measure of myocardial damage. To obtain an objective assessment of myocardial damage in DCM, we measured plasma levels of creatine kinase (CK), its isoenzymes (CK-MM and CK-MB), and separated the isoforms of CK-MM and CK-MB.

METHODS

The cohort consisted of 77 consecutive patients (61 men, 16 women) with DCM (World Health Organization criteria), aged 49 +/- 14 years (range 19-60). Patients had been symptomatic for 29 +/- 38 months (range 0.5-200 months) with 48 in New York Heart Association class I/II and 29 in class III/IV at the time of diagnosis. During median follow-up of 27 months from diagnosis (range 0.6-165), 50 patients remained clinically stable and 27 had deteriorated.

RESULTS

A significantly higher proportion of patients with DCM had abnormal MB2/MB1 ratio compared with normal volunteers (11, 14% vs. 1,1%, p = 0.003). Patients who deteriorated had higher MB2/MB1 ratio, (1.22 +/- 0.62 vs. 0.85 +/- 0.56; p = 0.01), and more frequently had abnormal MB2/ MB1 ratio (8, 30% vs. 3, 6%; p = 0.004) and CK and CK-MM activities (5, 19% vs. 2, 4%; p = 0.03) than those who remained stable. Patients with DCM with high CK-MB activity had 3.13-fold increased odds of sudden death or need for cardiac transplantation (95% confidence interval 1.53-6.40, p = 0.008). Thus, CK measurements, in particular CK-MB isoforms, are markers of myocardial damage in a subset of patients with DCM and could be useful in investigating the possibility of persistent myocardial damage in these patients.

Molecular evaluation of enteroviruses in the pathogenesis of idiopathic dilated cardiomyopathy

BACKGROUND

There is great disparity in the literature as to the presence and relevance of enterovirus in heart tissue from patients with dilated cardiomyopathy (DCM). Published estimates of enteroviral positive tissue in DCM range from 0 to 50%. Very little sequence information is so far available on those samples which are positive.

HYPOTHESIS

Re-examination of fresh biopsy material from patients previously tested, plus 13 new cases of DCM, and sequencing the products would yield information on the validity of the technique and on the type of virus being detected.

METHODS

RNA from biopsy or explant tissue was tested for the presence of enterovirus using reverse transcriptase polymerase chain reaction (PCR). The nucleotide sequences of all positive PCR products were determined by direct sequencing.

RESULTS

Positive PCR signals were found in 10% of samples from patients with DCM and in 16% of control tissues. Two DCM and 12 control samples gave the same nucleotide sequence, which was different from the CB3 used as a positive control. The other 4 DCM samples all produced multiple bands on sequencing.

CONCLUSION

The results do not support a major role for enterovirus in DCM. There is need for some caution, however, as a review of the literature shows that studies using single biopsies, such as this one, produce consistently lower estimates for enterovirus than do those wherein multiple biopsies are examined.

Utility of cough response during hypertonic histamine challenge in diagnosing asthma

Airway responses to bronchial provocation tests are traditionally assessed with spirometry which necessitates considerable patient co-operation. It has been shown that coughing during bronchial provocation tests is related to the degree of bronchoconstriction which, in turn, is independent of patient co-operation. The aim of the present study was to evaluate the utility of coughing induced by the hypertonic histamine challenge in the differential diagnosis of asthma in a clinically relevant patient population. The study population consisted of 25 healthy volunteers, 30 asthmatics, and 82 non-asthmatic subjects with respiratory symptoms due to other diseases. Hypertonic histamine solution was administered with ultrasonic nebuliser with the challenges being videotaped. The cough response was expressed as the cumulative number of coughs divided by the final histamine concentration administered (CCR). The geometric mean (95% CI) of CCR for asthmatics was 302 (166-562) coughs per mg/ml, for the symptomatic controls 29.5 (20.0-43.7) coughs per mg/ml (p<0.001) and for the healthy controls 6.61 (3.02-14.5) (p<0.001) coughs per mg/ml. According to the ROC curve, the optimal cut-off point for logCCR was 2.22, with the specificity and sensitivity to detect asthma among symptomatic subjects being 86% and 70%. Cough response to hyperosmolar challenge may be useful in the differential diagnosis of airway diseases.

Improvement in prognosis of dilated cardiomyopathy in the elderly over the past 20 years

BACKGROUND AND PURPOSE

Although dilated cardiomyopathy (DCM) had a poor prognosis in the past, recent studies have shown better survival. However, little is known about the improvement of prognosis in the elderly. This study sought to clarify the changes in prognosis in elderly patients with DCM over the past 20 years.

METHODS AND SUBJECTS

We studied 54 consecutive patients with DCM (38 men and 16 women, aged 65-83 years) who were diagnosed at over 65 years of age. The patients were divided into two groups (group A: 12 patients diagnosed before 1990; group B: 42 patients diagnosed after 1990) because after 1990, based on growing evidence from large-scale, randomized clinical studies, we intentionally increased the use of angiotensin-converting enzyme inhibitors (ACEI) and then beta-blockers at our hospital.

RESULTS

There were no significant differences in age, gender, NYHA functional class, and the prevalence of atrial fibrillation and ventricular tachycardia between the two groups. Left ventricular (LV) size assessed by echocardiography was larger (LV end-diastolic diameter, 67+/-5.9 versus 62+/-6.6 mm; p=0.039) and LV ejection fraction measured by left ventriculography was lower (ejection fraction, 24+/-9 versus 35+/-10%; p=0.004) in group A. ACEI/angiotensin II type 1 receptor blockers (ARB) (0% versus 88%) or beta-blockers (0% versus 52%) were more frequently used in group B. Antiarrhythmics (class Ia or Ib) (75% versus 14%) were less often used in group B. The 5- and 10-year event-free survival rates for cardiac death were 75.4% and 22.0% in group A versus 81.2% and 71.3% in group B (log-rank test, p=0.014).

CONCLUSIONS

The prognosis of DCM patients in the elderly has significantly improved over the past 20 years. The advances in the pharmacologic treatment and earlier diagnosis may have contributed to the better survival.

Differentiation of Ischemic and Dilated Cardiomyopathy on Electrocardiograms

Differentiating coronary artery disease with left ventricular dysfunction from dilated cardiomyopathy is important prognostically and therapeutically. To provide a diagnostic algorithm to distinguish these conditions using a standard 12-lead electrocardiogram, all 105 patients with left ventricular ejection fraction < 50% who underwent angiography between January 2004 and December 2006 were studied prospectively. Coronary artery disease was defined as ≥ 50% stenosis of the left main coronary artery or ≥ 70% stenosis of 1 or more of the 3 major epicardial arteries. Normal coronary angiography findings with left ventricular ejection fraction < 50% was defined as dilated cardiomyopathy. The most specific finding for differentiation of these diseases was pathologic Q waves in lead II, aVF, V3 or V4. The most sensitive parameter was a ratio ≥ 5 of R-wave amplitudes in lead V6 and lead III (94% sensitive). The 12-lead electrocardiogram provides a useful noninvasive method for differentiation of dilated cardiomyopathy from coronary artery disease with left ventricular systolic dysfunction.

Left ventricular myocardial performance index in closely-related relatives of patients with dilated cardiomyopathy

In this study, the left ventricular dimensions, systolic function, and left ventricular myocardial performance index in the first-degree relatives of the children with dilated cardiomyopathy (n=19), 30.0+/-17.6 years to normal age- and sex-matched controls (n=25), 27.4+/-17.7 years. The percentage ratio of the measured left ventricular end-diastolic dimension to the predicted left ventricular end-diastolic dimension (109+/-9.6 vs 105+/-11.8), left ventricular shortening fraction (34.5+/-6.6 vs 37.2+/-7%), and left ventricular ejection fraction (63.2+/-9.2 vs 66.5+/-8.1%) were not significantly different in the first-degree relatives and controls, respectively. However, the left ventricular myocardial performance index was significantly greater in the first-degree relatives than in controls (0.40+/-0.11 vs 0.31+/-0.03, p=0.01). In conclusion, the left ventricular myocardial performance index may be useful in early detect familial dilated cardiomyopathy in asymptomatic first-degree relatives of children with dilated cardiomyopathy.

Sudden death in competitive athletes

Sudden death in athletes is an extremely rare event yet no less tragic for its infrequency. Up to 90% of these deaths are due to underlying cardiovascular diseases and therefore categorized as sudden cardiac death (SCD). The causes of SCD among athletes are strongly correlated with age. In young athletes (<35 years), the leading causes are congenital cardiac diseases, particularly hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and congenital coronary artery anomalies. By contrast, most of deaths in older athletes (<35 years) are due to coronary artery disease. This review focuses on the cardiac causes of SCD and provides a brief summary of the principal noncardiac causes. Current pre-participation screening strategies are also discussed, with particular emphasis on the Italian experience.

The "Athlete's Heart": relation to gender and race

Long-term athletic training is associated with changes in cardiac morphology, commonly described as "athlete's heart." Although numerous studies have investigated the effects of training on cardiac dimensions, most are limited to male Caucasian athletes, and few data are available regarding the effect of long-term exercise training on the woman's heart. This article reviews the athlete's heart in relation to gender and race.

Recombinant lentivirus-delivered short hairpin RNAs targeted to conserved coxsackievirus sequences protect against viral myocarditis and improve survival rate in an animal model

Coxsackieviruses are important human pathogens that induce myocarditis and pancreatitis. However, there are no vaccines or therapeutic reagents for their clinical treatment. Although RNA interference (RNAi)-based approaches to the prevention of viral production have been developed recently, limitations to the in vivo delivery systems and variations in the viral target sequences still hamper the strategy. In this study, to overcome these limitations, we have constructed recombinant lentivirus-delivered short hairpin RNAs (shRNAs) against sequences in highly conserved cis-acting replication element (CRE) within the 2C protein of coxsackievirus B3 (CVB3), designated MET-2C. A recombinant lentivirus, designated Met-2C lenti, was constructed that contains the MET-2C sequence, which acts as a shRNA. Met-2C lenti clearly reduced viral production in CVB3-infected cells in vitro. Moreover, the mice injected intraperitoneally with Met-2C lenti had significant reductions in viral titers, viral myocarditis, and proinflammatory cytokines after challenge with CVB3, compared with those in GFP lenti infected control mice. Moreover, Met-2C lenti improved survival rate compared with that of the GFP lenti infected control group. Therefore, Met-2C lenti is potentially a clinical therapeutic agent for the treatment of viral myocarditis.

Reversible cardiomyopathies

Cardiomyopathy represents a diverse and heterogenous group of disorders affecting the myocardium and ultimately resulting in cardiac dysfunction. The prevalence of heart failure is high (5 million symptomatic patients in the United States) and increasing. Cardiomyopathy is the leading cause of hospitalization in patients older than 65 years of age, resulting in enormous healthcare expenditure and lost productivity. Ischemic cardiomyopathy accounts for about half of these patients, but in several large clinical trials the prevalence of potentially reversible nonischemic cardiomyopathy is also significant, ranging from 20% to 50%. There is epidemiological evidence that the prognosis of these reversible nonischemic cardiomyopathies is better than ischemic or other nonreversible cardiomyopathies. Early and precise diagnosis of the etiology of heart failure is important for determining prognosis and effective treatments.

Knock-in mouse model of dilated cardiomyopathy caused by troponin mutation

We created knock-in mice in which a deletion of 3 base pairs coding for K210 in cardiac troponin (cTn)T found in familial dilated cardiomyopathy patients was introduced into endogenous genes. Membrane-permeabilized cardiac muscle fibers from mutant mice showed significantly lower Ca(2+) sensitivity in force generation than those from wild-type mice. Peak amplitude of Ca(2+) transient in cardiomyocytes was increased in mutant mice, and maximum isometric force produced by intact cardiac muscle fibers of mutant mice was not significantly different from that of wild-type mice, suggesting that Ca(2+) transient was augmented to compensate for decreased myofilament Ca(2+) sensitivity. Nevertheless, mutant mice developed marked cardiac enlargement, heart failure, and frequent sudden death recapitulating the phenotypes of dilated cardiomyopathy patients, indicating that global functional defect of the heart attributable to decreased myofilament Ca(2+) sensitivity could not be fully compensated by only increasing the intracellular Ca(2+) transient. We found that a positive inotropic agent, pimobendan, which directly increases myofilament Ca(2+) sensitivity, had profound effects of preventing cardiac enlargement, heart failure, and sudden death. These results verify the hypothesis that Ca(2+) desensitization of cardiac myofilament is the absolute cause of the pathogenesis of dilated cardiomyopathy associated with this mutation and strongly suggest that Ca(2+) sensitizers are beneficial for the treatment of dilated cardiomyopathy patients affected by sarcomeric regulatory protein mutations.

Peripartum cardiomyopathy: a comprehensive review

Peripartum cardiomyopathy (PPCM) is a rare disorder in which left ventricular dysfunction and symptoms of heart failure occur in the peripartum period in previously healthy women. Incidence of PPCM ranges from 1 in 1300 to 1 in 15,000 pregnancies. The etiology of PPCM is unknown, but viral, autoimmune, and idiopathic causes may contribute. The diagnostic criteria are onset of heart failure in the last month of pregnancy or in first 5 months postpartum, absence of determinable cause for cardiac failure, and absence of a demonstrable heart disease before the last month of pregnancy. Risk factors for PPCM include advanced maternal age, multiparity, African race, twinning, gestational hypertension, and long-term tocolysis. The clinical presentation of patients with PPCM is similar to that of patients with dilated cardiomyopathy. Early diagnosis and initiation of treatment are essential to optimize pregnancy outcome. Treatment is similar to medical therapy for other forms of dilated cardiomyopathy. About half the patients of PPCM recover without complications. The prognosis is poor in patients with persistent cardiomyopathy. Persistence of disease after 6 months indicates irreversible cardiomyopathy and portends worse survival.

Utility of plasma apelin and other indices of cardiac dysfunction in the clinical assessment of patients with dilated cardiomyopathy

Apelin is a recently discovered peptide ligand reported to be involved in the regulation of cardiovascular homeostasis. The exact role of apelin in the pathophysiology of congestive heart failure has remained obscure, and the reported circulating levels of apelin in patients with heart failure have been contradictory. To establish the role of apelin in the assessment of cardiac dysfunction we measured plasma apelin levels in 65 patients with congestive heart failure caused by idiopathic dilated cardiomyopathy (IDC) and 14 healthy volunteers by specific radioimmunoassay. IDC patients were carefully examined including echocardiography, both-sided cardiac catheterization and cardiopulmonary exercise test. In addition, plasma levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), N-terminal pro-atrial natriuretic peptide (NT-proANP), interleukin (IL)-6, tumor necrosis factor alpha (TNF-alpha), epinephrine and norepinephrine were determined. Plasma apelin levels were similar in IDC patients (median 26.5 pg/ml, range<3.40-97.6 pg/ml) and in control subjects (median 24.1 pg/ml, range 19.0-28.7 pg/ml; p=NS). Unlike the levels of NT-proBNP, IL-6, TNF-alpha, and norepinephrine, plasma apelin levels did not reflect the severity of heart failure. Our study demonstrates that although disturbed apelin-APJ signalling in heart may play a role in the pathophysiology of heart failure, circulating apelin levels cannot be applied in the clinical assessment of patients with chronic left ventricular dysfunction.

Genetics of dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a myocardial disease characterized by dilatation and impaired systolic function of the left or both ventricles. The etiology of DCM is multifactorial, and many different clinical conditions can lead to the phenotype of DCM. During recent years it has become evident that genetic factors play an important role in the etiology and pathogenesis of idiopathic DCM. The genetics of DCM have been under intensive investigation lately, and thereby the knowledge on the genetic basis of DCM has increased rapidly. The genetic background of the disease seems to be relatively heterogeneous, and the disease-associated mutations concern mostly single families and only few affected patients. Disease-associated mutations have been detected e.g. in genes encoding sarcomere, cytoskeletal, and nuclear proteins, as well as proteins involved with regulation of Ca(2+) metabolism. The mechanisms, by which mutations eventually result in clinical heart failure, are complex and not yet totally resolved. DCM causes considerable morbidity and mortality. Better knowledge of the genetic background and disease-causing mechanisms would probably help us in focusing early treatment on right subjects and potentially also developing new treatment modalities and improving cardiac outcome in the affected patients. This review deals with DCM of genetic origin.

MHC class II genes in Mexican patients with idiopathic dilated cardiomyopathy

The purpose of the present study was to evaluate the relationship between class II major histocompatibility complex (MHC) genes (HLA-DR and HLA-DQB) and the genetic susceptibility to idiopathic dilated cardiomyopathy (IDC) in Mexican patients. The HLA-DR and DQB alleles were analyzed in 53 patients with IDC and 99 ethnically matched healthy controls using the polymerase chain reaction-sequence specific oligonucleotides (PCR-SSO) technique. IDC patients showed increased frequencies of HLA-DR4 (pC=0.02, OR=1.87), HLA-DQB1*0301 (pC=0.02, OR=1.92) and HLA-DQB1*0302 (pC=0.02, OR=1.87) when compared to healthy controls. On the other hand, IDC patients also showed decreased frequencies of HLA-DR11 allele (pC=0.03, OR=0.26) and HLA-DQB1*0201 (pC=0.04, OR=0.41). These data suggest that variation in class II HLA alleles could be a genetic factor involved in the susceptibility to IDC of the Mexican Mestizo population.

Cardiomyopathy, familial dilated

Dilated cardiomyopathy (DCM) is a heart muscle disease characterized by ventricular dilatation and impaired systolic function. Patients with DCM suffer from heart failure, arrhythmia, and are at risk of premature death. DCM has a prevalence of one case out of 2500 individuals with an incidence of 7/100,000/year (but may be under diagnosed). In many cases the disease is inherited and is termed familial DCM (FDC). FDC may account for 20–48% of DCM. FDC is principally caused by genetic mutations in FDC genes that encode for cytoskeletal and sarcomeric proteins in the cardiac myocyte. Family history analysis is an important tool for identifying families affected by FDC. Standard criteria for evaluating FDC families have been published and the use of such criteria is increasing. Clinical genetic testing has been developed for some FDC genes and will be increasingly utilized for evaluating FDC families. Through the use of family screening by pedigree analysis and/or genetic testing, it is possible to identify patients at earlier, or even presymptomatic stages of their disease. This presents an opportunity to invoke lifestyle changes and to provide pharmacological therapy earlier in the course of disease. Genetic counseling is used to identify additional asymptomatic family members who are at risk of developing symptoms, allowing for regular screening of these individuals. The management of FDC focuses on limiting the progression of heart failure and controlling arrhythmia, and is based on currently accepted treatment guidelines for DCM. It includes general measures (salt and fluid restriction, treatment of hypertension, limitation of alcohol intake, control of body weight, moderate exercise) and pharmacotherapy. Cardiac resynchronization, implantable cardioverter defibrillators and left ventricular assist devices have progressively expanding usage. Patients with severe heart failure, severe reduction of the functional capacity and depressed left ventricular ejection fraction have a low survival rate and may require heart transplant.

CD4 T Cells Play Major Effector Role and CD8 T Cells Initiating Role in Spontaneous Autoimmune Myocarditis of HLA-DQ8 Transgenic IAb Knockout Nonobese Diabetic Mice

In humans, spontaneous autoimmune attack against cardiomyocytes often leads to idiopathic dilated cardiomyopathy (IDCM) and life-threatening heart failure. HLA-DQ8 transgenic IAb knockout NOD mice (NOD.DQ8/Ab(0); DQA1*0301, DQB1*0302) develop spontaneous anticardiomyocyte autoimmunity with pathology very similar to human IDCM, but why the heart is targeted is unknown. In the present study, we first investigated whether NOD/Ab(0) mice transgenic for a different DQ allele, DQ6, (DQA1*0102, DQB1*0602) would also develop myocarditis. NOD.DQ6/Ab(0) animals showed no cardiac pathology, implying that DQ8 is specifically required for the myocarditis phenotype. To further characterize the cellular immune mechanisms, we established crosses of our NOD.DQ8/Ab(0) animals with Rag1 knockout (Rag1(0)), Ig H chain knockout (IgH(0)), and beta(2)-microglobulin knockout (beta(2)m(0)) lines. Adoptive transfer of purified CD4 T cells from NOD.DQ8/Ab(0) mice with complete heart block (an indication of advanced myocarditis) into younger NOD.DQ8/Ab(0) Rag1(0) animals induced cardiac pathology in all recipients, whereas adoptive transfer of purified CD8 T cells or B lymphocytes had no effect. Despite the absence of B lymphocytes, NOD.DQ8/Ab(0)IgH(0) animals still developed complete heart block, whereas NOD.DQ8/Ab(0)beta(2)m(0) mice (which lack CD8 T cells) failed to develop any cardiac pathology. CD8 T cells (and possibly NK cells) seem to be necessary to initiate disease, whereas once initiated, CD4 T cells alone can orchestrate the cardiac pathology, likely through their capacity to recruit and activate macrophages. Understanding the cellular immune mechanisms causing spontaneous myocarditis/IDCM in this relevant animal model will facilitate the development and testing of new therapies for this devastating disease.

Comparison of the epidemiology and co-morbidities of heart failure in the pediatric and adult populations: a retrospective, cross-sectional study

Background

Heart failure is a clinical syndrome that is associated with a significant number of interventional procedures and has received a large amount of scrutiny in the adult literature; however, the epidemiology in children is less well described.

Methods

We analyzed two large, commercially available inpatient datasets collected in 1997 by the Agency for Healthcare Research and Quality: the Kids' Inpatient Database and the National Inpatient Study, accounting for 50% of the U.S. pediatric discharges and 20% of the U.S. adult discharges in 1997.

Results

The database contained 5,610 children and 732,752 adults with a diagnosis of HF. When compared with the adult sample, the pediatric sample showed a higher proportion with cardiac procedures (61.4% vs. 0.28%, p < 0.01), a higher prevalence of congenital heart disease (61% versus 0.3%, p < 0.01), a higher percentage of male patients (50% pediatric vs. 44% adult, p < 0.01), and a lower percentage of white patients (40.9% vs. 65.6%, p < 0.01). Children had a significantly different spectrum of co-morbidities compared with adults. There was no difference in mortality rate between children and adults (7.5% vs. 7.9%, p = NS).

Conclusion

There are significant differences in the epidemiological profile of children and adults with heart failure. Children suffer from different types of co-morbidities and require different procedures in the hospital setting. As such, children with heart failure who are hospitalized may require significantly different facilities, management and therapeutic intervention than adults with similar symptoms.

Two novel mutations in the beta-myosin heavy chain gene associated with dilated cardiomyopathy

BACKGROUND

Dilated cardiomyopathy (DCM) is familial in approximately 20-35% of cases of idiopathic DCM. Several mutations in the different sarcomere protein genes have been reported to cause DCM.

AIMS

We wanted to investigate the role of sarcomere protein gene variants in Finnish DCM patients.

METHODS AND RESULTS

We screened all coding exons of five sarcomere protein genes (beta-myosin heavy chain, alpha-tropomyosin, troponin C, troponin I and troponin T) in a well-characterized population of 52 DCM patients in Eastern Finland by the PCR-SSCP and sequencing method. Two novel mutations, Arg1053Gln and Arg1500Trp, in the beta-myosin heavy chain gene in two index patients were detected. The proband with the Arg1053Gln mutation had a dilated left ventricle and impaired systolic function, but other family members carrying this mutation presented with septal hypertrophy. It thus seems that the Arg1053Gln mutation is primarily a HCM mutation, which can also lead to DCM. The other mutation, Arg1500Trp, was associated with a typical DCM phenotype. The Arg1500Trp mutation carrier had only one family member alive, but she did not carry the mutation and, therefore, cosegregation of the mutation and the disease in this family could not be reliably verified. No disease-causing mutations were found in the other sarcomere protein genes.

CONCLUSIONS

Two novel mutations in the beta-myosin heavy chain gene were detected in patients with DCM. Overall, mutations in the beta-myosin heavy chain gene seem to be relatively uncommon in Finnish DCM patients.

Left Ventricular Structural Adaptations to Obstructive Sleep Apnea in Dilated Cardiomyopathy

RATIONALE AND OBJECTIVES

Obstructive sleep apnea is common among patients with heart failure and exposes the left ventricle to trophic mechanical and adrenergic stimuli. We hypothesized that in heart failure patients with nonischemic dilated cardiomyopathy (a condition characterized by eccentric hypertrophy), those with obstructive sleep apnea would have a higher prevalence of left ventricular hypertrophy by wall thickness criteria (> or = 12 mm), and greater septal thickness than those without obstructive sleep apnea.

METHODS AND RESULTS

We performed echocardiography and polysomnography in 47 patients with nonischemic dilated cardiomyopathy. Obstructive sleep apnea was present in 45% of these patients. The prevalence of left ventricular hypertrophy was greater in those with than in those without obstructive sleep apnea (47.6 vs. 15.4%, p = 0.016). Interventricular septal thickness (p < 0.001) and relative wall thickness (p = 0.011) were significantly greater in those with than in those without obstructive sleep apnea. However, there was no significant difference in posterior wall thickness between the groups. The frequency of obstructive apneas and hypopneas during sleep was the only significant independent correlate of septal thickness (p = 0.001).

CONCLUSIONS

In patients with nonischemic dilated cardiomyopathy, the presence of obstructive sleep apnea is associated with an increased prevalence of left ventricular hypertrophy. The higher relative wall thickness and interventricular septal thickness in patients with obstructive sleep apnea indicate that the left ventricle is relatively less eccentric than in patients without obstructive sleep apnea, and that such remodeling affects mainly the septum. These structural adaptations may reflect unique nocturnal mechanical and adrenergic stimuli associated with obstructive sleep apnea.

Identification of a novel frameshift mutation in the giant muscle filament titin in a large Australian family with dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is an etiologically heterogeneous cardiac disease characterized by left ventricular dilation and systolic dysfunction. Approximately 25-30% of DCM patients show a family history of mainly autosomal dominant inheritance. We and others have previously demonstrated that mutations in the giant muscle filament titin (TTN) can cause DCM. However, the prevalence of titin mutations in familial DCM is unknown. In this paper, we report a novel heterozygous 1-bp deletion mutation (c.62890delG) in TTN that cosegregates with DCM in a large Australian pedigree (A3). The TTN deletion mutation c.62890delG causes a frameshift, thereby generating a truncated A-band titin due to a premature stop codon (p.E20963KfsX10) and the addition of ten novel amino acid residues. The clinical phenotype of DCM in kindred A3 demonstrates incomplete penetrance and variable expressivity. Finally, protein analysis of a skeletal muscle biopsy sample from an affected member did not reveal the predicted truncated titin isoform although the aberrant mRNA was present, suggesting posttranslational modification and degradation of the truncated protein. The identification of a novel disease-causing mutation in the giant titin gene in a third large family with DCM indicates that mutations in titin may account for a significant portion of the genetic etiology in familial DCM.

Molecular mimicry, bystander activation, or viral persistence: infections and autoimmune disease

Virus infections and autoimmune disease have long been linked. These infections often precede the occurrence of inflammation in the target organ. Several mechanisms often used to explain the association of autoimmunity and virus infection are molecular mimicry, bystander activation (with or without epitope spreading), and viral persistence. These mechanisms have been used separately or in various combinations to account for the immunopathology observed at the site of infection and/or sites of autoimmune disease, such as the brain, heart, and pancreas. These mechanisms are discussed in the context of multiple sclerosis, myocarditis, and diabetes, three immune-medicated diseases often linked with virus infections.

Beta1-adrenergic receptor gene polymorphisms in Mexican patients with idiopathic dilated cardiomyopathy

The objective of the study was to evaluate the role of beta1-adrenergic receptor gene polymorphisms (Ser49Gly and Arg389Gly) as susceptibility markers for idiopathic dilated cardiomyopathy (IDC) in Mexican patients. The polymorphisms were analyzed in 47 patients with IDC and 93 ethnically matched healthy controls by polymerase chain reaction-restriction fragment length polymorphism. The Ser49Gly allele and genotype frequencies were similar in patients and healthy controls. On the other hand, the analysis of the Arg389Gly polymorphism showed an increased frequencies of the *Gly allele (pC = 0.022, OR = 2.16) and *Arg/*Gly genotype (pC = 0.027, OR = 2.70) in the group of IDC patients when compared to healthy controls. The data suggest that Arg389Gly polymorphism could be involved in the genetic susceptibility to develop IDC in Mexicans.

National Institutes of Health-sponsored workshop on inflammation and immunity in dilated cardiomyopathy

Nonischemic dilated cardiomyopathy (DCM) is an uncommon cause of heart failure but has widespread importance because it is the cause of 45% of heart transplantations. Multiple experimental and clinical lines of evidence have implicated altered immunity in the pathogenesis of DCM. However, advances in the understanding of the mechanisms of altered immunity have not affected the diagnosis or treatment of DCM. In recognition of this problem, the National Institutes of Health sponsored an expert workshop with 2 aims: to review the current understanding of inflammation and immunity as they relate to DCM and to identify the most promising areas for future clinical research efforts in the field. This report summarizes the scientific opportunities, perceived needs and barriers, and workshop recommendations on research directions in DCM. The major recommendations from the members of the workshop are organized according to the following themes: cardiotropic viruses, innate and acquired immune responses, environmental factors, novel diagnostics, and novel therapeutics.

Human cardiac inflammatory responses triggered by Coxsackie B viruses are mainly Toll-like receptor (TLR) 8-dependent

The group B coxsackieviruses are single-stranded RNA viruses that have been implicated in viral myocarditis. Viral infection of the myocardium, as well as the associated inflammatory response are important determinants of the virus-associated myocardial damage. Although these viruses are known as cytopathic viruses that cause death of the host cell, their viral RNA has been shown to persist in cardiac muscle contributing to a chronic inflammatory cardiomyopathy. Thus, it is essential that we understand the mechanism by which Coxasckie B viruses (CBVs) trigger this inflammatory response. In this study we investigated the involvement of Toll-like receptors (TLRs) in the recognition of CBV virions as well as CBV single-stranded RNA. Here we report that the CBV-induced inflammatory response is mediated through TLR8 and to a lesser extent through TLR7.

A novel locus for autosomal-dominant dilated cardiomyopathy maps to chromosome 7q22.3-31.1

Inherited dilated cardiomyopathy (DCM) is a genetically and phenotypically very heterogeneous disease. DCM is caused by mutations in multiple genes encoding proteins that are involved in force generation, force transmission, energy production and several signalling pathways. Thus, the pathophysiology of heart failure is complex and not yet fully understood. Familial forms of DCM let the way to identify new key proteins by positional cloning and to study respective pathomechanisms that are critical for normal cardiac function, but may not have been correlated with heart disease before. Here we report a three-generation pedigree including 16 individuals affected by dilated cardiomyopathy without additional phenotypes. The pedigree is consistent with autosomal-dominant inheritance and age-related penetrance. A genome-wide linkage analysis excluded linkage to all known DCM genes and loci, whereas several close markers on chromosome 7q22.3-31.1 segregated with the disease (maximum logarithm of odds score, 4.20 at D7S471 and D7S501). The disease causing mutation lies in a 9.73 Mb interval between markers D7S2545 and D7S2554 that contains no known cytoskeletal genes. Coding exons of the candidate genes LAMB1, LAMB4 and PIK3CG were screened but no mutations were identified.

Dilated cardiomyopathy and acute liver injury associated with combined use of ephedra, gamma-hydroxybutyrate, and anabolic steroids

Anabolic-androgenic steroids are synthetic derivatives of testosterone that some athletes have used to enhance muscle mass and improve their athletic performance. Ephedrine is a potent sympathomimetic agent that can lead to cardiomyopathy similar to that seen with catecholamine excess. Adverse cardiovascular events attributed to anabolic steroid and ephedra use, such as arrhythmias, myocardial infarction, cardiomyopathy, and sudden death, are rarely reported. Bodybuilders have used gamma-hydroxybutyrate, a potent secretagogue of growth hormone, to promote muscle development. Although dilated cardiomyopathy is a known complication of excess growth hormone levels, it has not been associated with use of gamma-hydroxybutyrate. A healthy 40-year-old man was admitted to our hospital for new-onset congestive heart failure and severe acute hepatitis that developed several months after he began using anabolic-androgenic steroids, ephedra, and gamma-hydroxybutyrate supplements. Analysis with an objective causality assessment scale revealed a probable adverse drug reaction between the patient's use of anabolic steroids, ephedra, and gamma-hydroxybutyrate and the development of his cardiomyopathy and acute liver injury.

Idiopathic dilated cardiomyopathy in children: a single medical center's experience

BACKGROUND

The prognosis of patients with idiopathic dilated cardiomyopathy (DCM) is poor. Most patients die while waiting for cardiac transplantation because of the small number of donors in Taiwan. The purpose of this study was to review our experience with pediatric patients diagnosed with idiopathic DCM and attempt to discover prognostic factors.

METHODS

Eighteen patients with idiopathic DCM presenting between 1990 and 2004 were identified. They were classified into 2 groups according to outcome: group 1 comprised 13 patients who died; group 2 comprised 5 who survived. Clinical findings and laboratory investigations were compared between the 2 groups.

RESULTS

The age at initial diagnosis for the 18 patients (11 males, 7 females) ranged from fetus to 13 years (median, 3 months). The follow-up period ranged from 12 days to 44 months (median, 7 months) in group 1, and from 1 to 48 months (median, 39 months) in group 2. Of the 18 patients, 13 (72%) died: 11 died from severe heart failure while waiting for cardiac transplantation. The cumulative survival rate was 50% at 1 year and 28% at 4 years. The presence of arrhythmia and low left ventricular ejection fraction were predictive of a poor outcome.

CONCLUSION

The diagnosis of idiopathic DCM in children is associated with a generally poor prognosis. The lack of available donors results in significant mortality for pediatric patients awaiting transplantation. Advocating organ donation to increase the size of the organ donor pool is needed to significantly reduce the mortality rate in such patients.

The effect of coenzyme Q10 on idiopathic chronic dilated cardiomyopathy in children

The objective of this study was to assess the effect of coenzyme Q10 (CoQ10) as supplementation to conventional antifailure drugs on quality of life and cardiac function in children with chronic heart failure due to dilated cardiomyopathy (DCM). The study was an open-label prospective study performed in two of the largest pediatric centers in Thailand from August 2000 to June 2003. A total of 15 patients with idiopathic chronic DCM were included, with the median age of 4.4 years (range, 0.6-16.3). Presenting symptoms were congestive heart failure in 12 cases (80%), cardiogenic shock in 2 cases (13.3%), and cardiac arrhythmia in 1 case (6.7%). Sixty-one percent of patients were in the New York Heart Association functional class 2 (NYHA 2), 31% in NYHA 3, and 8% in NYHA 4. Cardiothoracic ratio from chest x-ray, left ventricular ejection fraction, and left ventricular end diastolic dimension in echocardiogram were 0.62 (range, 0.55-0.78), 30% (range, 20-40), and 5.2 cm (range, 3.8-6.5), respectively. CoQ10 was given at a dosage of 3.1 ? 0.6 mg/kg/day for 9 months as a supplementation to a fixed amount of conventional antifailure drugs throughout the study. At follow-up periods of 1, 3, 6, and 9 months, NYHA functional class was significantly improved, as was CT ratio and QRS duration at 3 and 9 months follow-up with CoQ10 when compared to the baseline and post-discontinuation of CoQ10 at 9 months (range, 4.8-10.8). However, when multiple comparisons were taken into consideration, there was no statistical significant improvement. In addition to the conventional antifailure drugs, CoQ10 may improve NYHA class and CT ratio and shorten ventricular depolarization in children with chronic idiopathic DCM.

Hereditary hemochromatosis gene (HFE) mutations C282Y, H63D and S65C in patients with idiopathic dilated cardiomyopathy

BACKGROUND

Hereditary hemochromatosis (HH), a common autosomal recessive disease, leads to excessive iron accumulation in some organs, including the heart. It is therefore not surprising that cardiomyopathy is one of the most severe complications of HH. The HFE gene defects have been thought to contribute to idiopathic dilated cardiomyopathy (IDCM) in some patients, even though the results of genotype analyses have so far been contradictory. Hence we set out here to evaluate the prevalence and potential role of HFE mutations in patients with IDCM.

METHODS

A total of 91 IDCM patients and 102 controls were subjected to HFE mutation analyses, in which C282Y, H63D and S65C mutations were determined for each patient. We also analyzed the impact of the C282Y and H63D mutations on the left ventricular end-diastolic diameter (LVEDD), left ventricular ejection fraction (LVEF) and New York Heart Association (NYHA) functional classes.

RESULTS

The prevalences of heterozygosity for the C282Y, H63D and S65C mutations in the IDCM patients were 13.2%, 22.0% and 2.2%, respectively. LVEDD was significantly higher (P=0.037) in those with the C282Y mutation at the end of the follow-up period than in those with no mutation.

CONCLUSIONS

Our data showed no significant deviations in C282Y, H63D and S65C mutation frequencies between the IDCM patients and controls, suggesting that these mutations do not increase the risk of IDCM. Heterozygosity for the C282Y mutation may nevertheless be a modifying factor contributing to LV dilatation and remodeling.

Myocarditis, microbes and autoimmunity

Acute and chronic myocarditis can be caused by a number of infectious agents, including viruses, bacteria and protozoa. These diseases are refractory to treatment, and the development of rational therapies will require a detailed understanding of the mechanisms that underlie the pathological inflammatory responses. Here, we review three infectious myocarditides that, despite the dissimilarity of the microorganisms, share several common features: (i) the microbes replicate in the heart; but (ii) are difficult to isolate, in infectious form, during chronic disease; (iii) autoreactive antibodies and T cells specific for cardiac antigens have been identified in infected animals; and (iv) these autoreactive responses have been proposed as the main effectors of cell death, and myocardial damage. We critically evaluate the data, and we suggest that the findings can be reconciled without invoking autoimmunity as an effector mechanism. Alternative hypotheses to explain the tissue destruction are proposed.

Sodium channel mutations and susceptibility to heart failure and atrial fibrillation

CONTEXT

Dilated cardiomyopathy (DCM), a genetically heterogeneous disorder, causes heart failure and rhythm disturbances. The majority of identified DCM genes encode structural proteins of the contractile apparatus and cytoskeleton. Recently, genetic defects in calcium and potassium regulation have been discovered in patients with DCM, implicating an alternative disease mechanism. The full spectrum of genetic defects in DCM, however, has not been established.

OBJECTIVES

To identify a novel gene for DCM at a previously mapped locus, define the spectrum of mutations in this gene within a DCM cohort, and determine the frequency of DCM among relatives inheriting a mutation in this gene.

DESIGN, SETTING, AND PARTICIPANTS

Refined mapping of a DCM locus on chromosome 3p in a multigenerational family and mutation scanning in 156 unrelated probands with DCM, prospectively identified at the Mayo Clinic between 1987 and 2004. Relatives underwent screening echocardiography and electrocardiography and DNA sample procurement.

MAIN OUTCOME MEASURE

Correlation of identified mutations with cardiac phenotype.

RESULTS

Refined locus mapping revealed SCN5A, encoding the cardiac sodium channel, as a candidate gene. Mutation scans identified a missense mutation (D1275N) that cosegregated with an age-dependent, variably expressed phenotype of DCM, atrial fibrillation, impaired automaticity, and conduction delay. In the DCM cohort, additional missense (T220I, R814W, D1595H) and truncation (2550-2551insTG) SCN5A mutations, segregating with cardiac disease or arising de novo, were discovered in unrelated probands. Among individuals with an SCN5A mutation 27% had early features of DCM (mean age at diagnosis, 20.3 years), 38% had DCM (mean age at diagnosis, 47.9 years), and 43% had atrial fibrillation (mean age at diagnosis, 27.8 years).

CONCLUSIONS

Heritable SCN5A defects are associated with susceptibility to early-onset DCM and atrial fibrillation. Similar or even identical mutations may lead to heart failure, arrhythmia, or both.

Diagnostic approach to the patient with cardiomyopathy: whom to biopsy

The prevalence of congestive heart failure is increasing and the prognosis remains poor. Cardiomyopathy is one of the most frequent causes of congestive heart failure and is the most common etiology of patients submitted to heart transplant. Determination of the etiology of cardiomyopathy has both prognostic and therapeutic implications. History, physical examination, transthoracic echocardiogram, selected laboratory studies, and coronary angiography can often define the cause of cardiomyopathy, however, the etiology occasionally remains unknown despite this initial evaluation. The indications for endomyocardial biopsy (EMBx) in patients with cardiomyopathy and a negative initial evaluation remains uncertain. The search for Dallas histological criteria proven myocarditis prompted the performance of EMBx in patients with unexplained cardiomyopathy in hopes of identifying an etiology for which treatment would result in improvement in left ventricular function. The "negative" results of the Myocarditis Treatment Trial, with treated and controlled patients improving equally, dampened enthusiasm for this diagnostic procedure. However, our experience and recent evidence suggests that EMBx may be a valuable diagnostic modality and should be included in the evaluation of patients with initially unexplained cardiomyopathy.