Clinical course of idiopathic dilated cardiomyopathy in children

Longitudinal Prediction of Transplant-Free Survival by Echocardiography in Pediatric Dilated Cardiomyopathy

BACKGROUND

The prognostic significance of serial echocardiography and its rate of change in children with dilated cardiomyopathy (DCM) is incompletely defined.

METHODS

We retrospectively analysed up to 4 serial echocardiograms. Associations between mortality/transplant and echocardiographic parameters over time and between outcomes and the rate of change of echocardiographic parameters were analysed. Estimation of patient-specific intercepts and slopes was done using linear regression models.

RESULTS

Fifty-seven DCM children were studied (50% male; median age, 0.6 year; average follow-up, 2.1 ± 2.4 years). The median time to transplant or death was 2.0 years. Increased left ventricular (LV) diastolic (LVEDD) and systolic (LVESD) dimensions and myocardial performance index (MPI) were associated with increased mortality and transplant risk. Increased LV ejection fraction, mitral E-deceleration time, right ventricular (RV) fractional area change, and tricuspid annular plane systolic excursion were associated with reduced mortality and transplant risk. Transplant/mortality likelihood increased by 41.6% and 19.8% for each unit increase in LVEDD and LVESD z scores, respectively (LVEDD: hazard ratio [HR], 1.416; 95% confidence interval [CI], 1.285-1.560; P < 0.001; LVESD: HR, 1.198; 95% CI, 1.147-1.251; P < 0.001). A higher monthly change in LVESD z score increased transplant/mortality likelihood by 85.6% (HR, 1.856; 95% CI, 1.572-2.191; P = 0.015). Greater changes in mitral E/e' (HR, 0.707; 95% CI, 0.636-0.786; P < 0.001) and RV MPI (HR, 0.412; 95% CI, 0.277-0.613; P < 0.001) were associated with reduced mortality and transplant risk.

CONCLUSIONS

LV and RV systolic and diastolic dimensions and function over time and their rate of change are associated with risk for transplant and mortality in childhood DCM. Serial changes in these parameters may be useful to predict clinical outcomes.

Wearable cardioverter-defibrillators in pediatric cardiomyopathy: A cost-utility analysis

BACKGROUND

Dilated cardiomyopathy (DCM) is the most common cardiomyopathy in children. Patients with severe cardiac dysfunction are thought to be at risk of sudden cardiac arrest (SCA). After diagnosis, a period of medical optimization is recommended before permanent implantable cardioverter-defibrillator (ICD) implantation. Wearable cardioverter-defibrillators (WCDs) provide an option for arrhythmia protection as an outpatient during this optimization.

OBJECTIVE

The purpose of this study was to determine the strategy that optimizes cost and survival during medical optimization of a patient with DCM before ICD placement.

METHODS

A Markov state transition model was constructed for the 3 clinical approaches to compare costs, clinical outcomes, and quality of life: (1) "Inpatient," (2) "Home-WCD," and (3) "Home-No WCD." Transitional probabilities, costs, and utility metrics were extracted from the existing literature. Cost-effectiveness was assessed comparing each paradigm's incremental cost-effectiveness ratio against a societal willingness-to-pay threshold of $50,000 per quality-adjusted life year.

RESULTS

The cost-utility analysis illustrated that Home-WCD met the willingness-to-pay threshold with an incremental cost-effectiveness ratio of $20,103 per quality-adjusted life year and 4 mortalities prevented per 100 patients as compared with Home-No WCD. One-way sensitivity analyses demonstrated that Home-No WCD became the most cost-effective solution when the probability of SCA fell below 0.2% per week, the probability of SCA survival with a WCD fell below 9.8%, or the probability of SCA survival with Home-No WCD quadrupled from base-case assumptions.

CONCLUSION

Based on the existing literature probabilities of SCA in pediatric patients with DCM undergoing medical optimization before ICD implantation, sending a patient home with a WCD may be a cost-effective strategy.

Clinical Characteristics and Treatment of Cardiomyopathies in Children

Cardiomyopathies are diseases of the heart muscle, a term introduced in 1957 to identify a group of myocardial diseases not attributable to coronary artery disease. The definition has since been modified to refer to structural and or functional abnormalities of the myocardium where other known causes of myocardial dysfunction, such as systemic hypertension, valvular disease and ischemic heart disease, have been excluded. In this review, we discuss the pathophysiology, clinical assessment and therapeutic strategies for hypertrophic, dilated and hypertrophic cardiomyopathies, with a particular focus on aspects unique to children.

Paediatric dilated cardiomyopathy: clinical profile and outcome. The experience of a tertiary centre for paediatric cardiology

Dilated cardiomyopathy is the most common form of cardiomyopathy in the paediatric population and an important cause of heart transplantation in children. The clinical profile and course of dilated cardiomyopathy in children have been poorly characterised. A retrospective review of 61 patients (37 female; 24 male) diagnosed with dilated cardiomyopathy from January, 2005 to June, 2012 at a single institution was performed. The median age at diagnosis was 15 months. Heart failure was present in 83.6% of patients and 44.3% required intensive care. The most prevalent causes were idiopathic (47.5%), viral myocarditis (18.0%) and inherited metabolic diseases (11.5%). In viral myocarditis, Parvovirus B19 was the most common identified agent, in concurrence with the increasing incidence documented recently. Inherited metabolic diseases were responsible for 11.5% of dilated cardiomyopathy cases compared with the 4-6% described in the literature, which reinforces the importance of considering this aetiology in differential diagnosis of paediatric dilated cardiomyopathy. The overall mortality rate was 16.1% and five patients underwent heart transplantation. In our series, age at diagnosis and aetiology were the most important prognosis factors. We report no mortality in the five patients who underwent heart transplantation, after 2 years of follow-up.

Safety and efficacy of the off-label use of milrinone in pediatric patients with heart diseases

Background and Objectives

Milrinone is often used in children to treat acute heart failure and prevent low cardiac output syndrome after cardiac surgery. Due to the lack of studies on the long-term milrinone use in children, the objective of this study was to assess the safety and efficacy of the current patterns of milrinone use for ≥3 days in infants and children with heart diseases.

Subjects and Methods

We retrospectively reviewed the medical records of patients aged <13 years who received milrinone for ≥3 days from January 2005 to December 2012. Patients' characteristics including age, sex, height, weight, and body surface area were recorded. The following parameters were analyzed to identify the clinical application of milrinone: initial infusion rate, maintenance continuous infusion rate, total duration of milrinone therapy, and concomitantly infused inotropes. The safety of milrinone was determined based on the occurrence of adverse events such as hypotension, arrhythmia, chest pain, headache, hypokalemia, and thrombocytopenia.

Results

We assessed 730 admissions (684 patients) during this period. Ventricular septal defects were the most common diagnosis (42.4%) in these patients. Milrinone was primarily used after cardiac surgery in 715 admissions (97.9%). The duration of milrinone treatment varied from 3 to 64.4 days (≥7 days in 149 admissions). Ejection fraction and fractional shortening of the left ventricle improved in patients receiving milrinone after cardiac surgery. Dose reduction of milrinone due to hypotension occurred in only 4 admissions (0.5%). Although diverse arrhythmias occurred in 75 admissions (10.3%), modification of milrinone infusion to manage arrhythmia occurred in only 3 admissions (0.4%). Multivariate analysis indicated that the development of arrhythmia was not influenced by the pattern of milrinone use.

Conclusion

Milrinone was generally administered for ≥3 days in children with heart diseases. The use of milrinone for ≥3 days was effective in preventing low cardiac output after cardiac surgery when combined with other inotropes, suggesting that milrinone could be safely employed in pediatric patients with heart diseases.

Recovery of echocardiographic function in children with idiopathic dilated cardiomyopathy: results from the pediatric cardiomyopathy registry

OBJECTIVES

This study sought to determine the incidence and predictors of recovery of normal echocardiographic function among children with idiopathic dilated cardiomyopathy (DCM).

BACKGROUND

Most children with idiopathic DCM have poor outcomes; however, some improve.

METHODS

We studied children <18 years of age from the Pediatric Cardiomyopathy Registry who had both depressed left ventricular (LV) function (fractional shortening or ejection fraction z-score <-2) and LV dilation (end-diastolic dimension [LVEDD] z-score >2) at diagnosis and who had at least 1 follow-up echocardiogram 30 days to 2 years from the initial echocardiogram. We estimated the cumulative incidence and predictors of normalization.

RESULTS

Among 868 children who met the inclusion criteria, 741 (85%) had both echocardiograms. At 2 years, 22% had recovered normal LV function and size; 51% had died or undergone heart transplantation (median, 3.2 months), and 27% had persistently abnormal echocardiograms. Younger age (hazard ratio [HR]: 0.92; 95% confidence interval [CI]: 0.88 to 0.97) and lower LVEDD z-score (HR: 0.78; 95% CI: 0.70 to 0.87) independently predicted normalization. Nine children (9%) with normal LV function and size within 2 years of diagnosis later underwent heart transplantation or died.

CONCLUSIONS

Despite marked LV dilation and depressed function initially, children with idiopathic DCM can recover normal LV size and function, particularly those younger and with less LV dilation at diagnosis. Investigations related to predictors of recovery, such as genetic associations, serum markers, and the impact of medical therapy or ventricular unloading with assist devices are important next steps. Longer follow-up after normalization is warranted as cardiac failure can recur. (Pediatric Cardiomyopathy Registry; NCT00005391).

Electrophysiological interventions for treatment of congestive heart failure in pediatrics and congenital heart disease

Heart failure therapy, while well tested in the adult population, therapeutic interventions are less well defined in the pediatric population. Several treatment strategies are available for the adult patient with heart failure, thought few of these therapies have been proven in children. Morbidity and mortality in the pediatric population with a failing heart is significant, and rhythm management as well as strategies to improve hemodynamics are important in the care of these children. This review will address issues of rhythm management and resynchronization therapy in pediatric and congenital heart disease patients with heart failure.

Anaemia is a predictor of early death or cardiac transplantation in children with idiopathic dilated cardiomyopathy

INTRODUCTION

The aim of our study was to establish the prevalence and the prognostic value of haematological abnormalities in children with cardiac failure.

PATIENTS AND METHODS

A series of 218 consecutive children with a first diagnosis of idiopathic dilated cardiomyopathy were retrospectively examined. Haematological evaluation was performed at first diagnosis. Death or cardiac transplantation was the main outcome measure.

RESULTS

The median age was 0.6 years, ranging from 1 day to 15.8 years and median follow-up was 2.65 years, ranging from 0 to 17.2 years. After a median interval of 0.2 years, ranging from 0 to 8.7 years, 56 patients died and 25 were transplanted. Event-free survival at 1 and 5 years was 68% (95% confidence interval, 63-75%) and 62% (95% confidence interval, 56-69%). Blood levels of haemoglobin less than 10 grams per decilitre, urea over 8 millimoles per litre, and C-reactive protein over 10 milligrams per litre were found in 24%, 20%, and 24% of patients, respectively. The log-rank test showed that haemoglobin (p = 0.000) and C-reactive protein (p = 0.021) were predictors of death or transplantation. In the multivariate Cox model, haemoglobin (hazard ratio = 0.735; confidence interval = 0.636-0.849; p = 0.000) and urea (hazard ratio = 1.083; confidence interval = 1:002-1:171; p = 0.045) were predictive of poor outcome. Cubic spline functions showed that the positive role of haemoglobin on survival was linear for values less than 12 grams per decilitre and null for values more than 12 grams per decilitre. Adaptive index models for risk stratification and Classification and Regression Tree analysis allowed to identify the cut-off values for haemoglobin (less than 10.2 grams per decilitre) and urea (more than 8.8 millimoles per litre), as well as to derive a predictor model.

CONCLUSIONS

In children with idiopathic dilated cardiomyopathy, anaemia is the strongest independent prognostic factor of early death or transplantation.

Incidence of and risk factors for sudden cardiac death in children with dilated cardiomyopathy: a report from the Pediatric Cardiomyopathy Registry

OBJECTIVES

The purpose of this study was to establish the incidence of and risk factors for sudden cardiac death (SCD) in pediatric dilated cardiomyopathy (DCM).

BACKGROUND

The incidence of SCD in children with DCM is unknown. The ability to predict patients at high risk of SCD will help to define who may benefit most from implantable cardioverter-defibrillators.

METHODS

The cohort was 1,803 children in the PCMR (Pediatric Cardiomyopathy Registry) with a diagnosis of DCM from 1990 to 2009. Cumulative incidence competing-risks event rates were estimated. We achieved risk stratification using Classification and Regression Tree methodology.

RESULTS

The 5-year incidence rates were 29% for heart transplantation, 12.1% non-SCD, 4.0% death from unknown cause, and 2.4% for SCD. Of 280 deaths, 35 were SCD, and the cause was unknown for 56. The 5-year incidence rate for SCD incorporating a subset of the unknown deaths is 3%. Patients receiving antiarrhythmic medication were at higher risk of SCD (hazard ratio: 3.0, 95% confidence interval: 1.1 to 8.3, p = 0.025). A risk stratification model based on most recent echocardiographic values had 86% sensitivity and 57% specificity. Thirty of 35 SCDs occurred in patients who met all these criteria: left ventricular (LV) end-systolic dimension z-score >2.6, age at diagnosis younger than 14.3 years, and the LV posterior wall thickness to end-diastolic dimension ratio <0.14. Sex, ethnicity, cause of DCM, and family history were not associated with SCD.

CONCLUSIONS

The 5-year incidence rate of SCD in children with DCM is 3%. A risk stratification rule (86% sensitivity) included age at diagnosis younger than 14.3 years, LV dilation, and LV posterior wall thinning. Patients who consistently meet these criteria should be considered for implantable cardioverter-defibrillator placement.

Usefulness of mitral regurgitation as a marker of increased risk for death or cardiac transplantation in idiopathic dilated cardiomyopathy in children

In adults with idiopathic dilated cardiomyopathy (IDC), mitral regurgitation (MR) is associated with adverse prognosis and is often addressed by surgery or intervention. MR is commonly found in children with IDC, but its prognostic relevance has not been defined, and interventions to reduce MR are not routinely performed in this population. In this study, it was hypothesized that MR is an independent risk factor for death or transplantation. This was a single-center, retrospective study of sequential patients with IDC or familial IDC (left ventricular end-diastolic dimension z score >2 and ejection fraction <50%). Patients with acute myocarditis or previous mitral surgery were excluded. MR severity was graded according to American Society of Echocardiography guidelines as mild, moderate, or severe on the basis of MR jet vena contracta width. Left ventricular end-diastolic volume, end-systolic volume, and ejection fraction were measured by biplane Simpson's method. Forty-two children with IDC were studied. The mean follow-up period was 25 months. At initial assessment, 34 children (82%) were taking angiotensin-converting enzyme inhibitors, 25 (60%) furosemide, 27 (65%) β blockers, and 7 (17%) intravenous inotropes. The mean indexed end-systolic volume was 91 ± 51 ml/m(2). The mean ejection fraction was 27 ± 16%. MR was mild in 42%, moderate in 19%, severe in 2%, and absent in 35% of patients. MR severity progressed from initial to last evaluation. MR severity was an independent risk factor for lower freedom from death or transplantation. Progression in MR severity increased the annual hazard of death or transplantation by a factor of 2.4 (p = 0.003). In conclusion, MR severity is independently associated with worse clinical status and decreased freedom from death or transplantation in children with IDC.

Early changes in right ventricular function and their clinical consequences in childhood and adolescent dilated cardiomyopathy

The aim of the paper was to investigate the right ventricle in paediatric dilated cardiomyopathy. We examined 11 patients with dilated cardiomyopathy as well as 12 normal paediatric controls. Cardiac magnetic resonance imaging was performed for ventricular size and function. N-terminal pro-brain natriuretic peptide was collected at this time and the results from the most recent echocardiogram and exercise test were reviewed.We found that patients with dilated cardiomyopathy had significantly faster heart rates, that is, 85 versus 65 beats per minute, lower left ventricular ejection fraction, that is, 42 versus 61%, and right ventricular ejection fraction of 44 versus 54%, lower left and right ventricular stroke volumes, that is, 35.5 versus 49.5 millilitres per square metre and 40.9 versus 56.4 millilitres per square metre, respectively, and lower mitral and tricuspid valve inflow e/a wave velocity ratios of 2.02 versus 2.80 and 1.25 versus 2.58, respectively, than the controls. Tricuspid valve annulus velocity, measured by tissue Doppler echocardiography, correlated with right ventricular ejection fraction (r = 0.60, p = 0.05). Right ventricular ejection fraction and indexed right ventricular end-diastolic volume correlated with N-terminal pro-brain natriuretic peptide (r = -0.67, p = 0.03, r = 0.65, p = 0.04, respectively), and right ventricular ejection fraction correlated with the oxygen uptake at the anaerobic threshold (r = 0.67, p = 0.049). Neither left ventricular ejection fraction nor left ventricular volume correlated with N-terminal pro-brain natriuretic peptide or exercise tolerance. The right ventricular function is decreased in the early stages of dilated cardiomyopathy. Right ventricular size and ejection fraction may be important indicators of sub-clinical cardiac failure and we suggest monitoring them routinely in dilated cardiomyopathy.

Frequency of cardiac death in children with idiopathic dilated cardiomyopathy

The prognosis in children with idiopathic dilated cardiomyopathy (IDC) is guarded, with the 5-year mortality rate ranging from 14% to 50%, owing to sudden cardiac death (SCD) or pump failure. The risk factors for SCD in adults with IDC include asymptomatic nonsustained ventricular tachycardia and poor left ventricular function. It is unclear whether these findings can be extrapolated to the pediatric population. A retrospective review of all patients with the diagnosis of IDC seen at a single institution from 1990 to 2004 was performed. A total of 85 patients (46 males), with a median age of 3.8 years (0 days to 17.3 years) were studied. The mean left ventricular ejection fraction was 25 +/- 12% (median 23%, range 45% to 45%) at presentation. The following arrhythmias occurred at presentation or during the initial hospitalization: nonsustained ventricular tachycardia in 6, sustained ventricular tachycardia or fibrillation in 1, supraventricular arrhythmias in 6, and both atrial and ventricular arrhythmias in 1. During a subsequent hospitalization or outpatient follow-up, 7 patients had the following arrhythmias: supraventricular arrhythmias in 2, nonsustained ventricular tachycardia in 4, and both atrial and ventricular arrhythmias in 1. The cumulative survival rate was 40% at a mean follow-up of 6.2 years (95% confidence interval 4.4 to 8.1). One single episode of SCD occurred in 1 patient without a history of sustained arrhythmias. In conclusion, in children with IDC, despite the low left ventricular ejection fraction and presence of ventricular arrhythmias, only one episode of SCD occurred in this group of patients. Given the 1% incidence of SCD in this cohort, the use of implantable cardioverter-defibrillators as primary prevention in children with IDC might not be indicated.

Routine performance of endomyocardial biopsy decreases the incidence of orthotopic heart transplant for myocarditis

BACKGROUND

In critically ill children presenting with dilated cardiomyopathy (DCM), the presence of myocarditis predicts an improved chance of myocardial recovery. Noninvasive differentiation of myocarditis from other causes of DCM is difficult. However, sensitivity of endomyocardial biopsy has been questioned.

METHODS

We reviewed clinical, echocardiographic, catheterization, and pathology data from all children admitted to the intensive care unit with DCM undergoing orthotopic heart transplantation since the inception of our transplant program in 1987 and all patients with definitively diagnosed myocarditis presenting since 1996.

RESULTS

Thirty-six patients with DCM underwent orthotopic heart transplantation. Cellular infiltrate was present in 3 of 36 (8.3%) explanted specimens. Pre-transplant biopsy was performed in 81%. No explanted heart demonstrated infiltrates after a negative biopsy. One biopsy was positive with negative explant histology after transplant 6 months later. No patient with biopsy-proven myocarditis died while listed for transplantation. Eleven additional patients with myocarditis did not undergo transplant. Ten have survived and experienced complete (n = 9) or near complete (n = 1) recovery of myocardial function. One patient died shortly after presentation from fulminant myocarditis. The 10 transplant-free survivors could not be easily distinguished from our transplant cohort by clinical features at presentation.

CONCLUSION

The incidence of cellular infiltrate in explanted hearts was significantly lower than that previously reported. Potentially, our aggressive myocarditis diagnostic protocol was useful in therapeutic stratification as a cohort of myocarditis patients avoided transplant and experienced complete recovery of myocardial function despite being difficult to distinguish clinically from our DCM transplant cohort at presentation.

Rhythm management in pediatric heart failure

There are several options now available for the management of arrhythmias and ventricular dysfunction in pediatric patients with heart failure. A hybrid approach that combines the expertise of heart failure and electrophysiology specialists may be well suited for the optimal management of these complex patients. Medical and device therapies may be synergistic in decreasing the morbidity and mortality in pediatric heart failure. Pediatric electrophysiology can now potentially offer therapies that can help prevent both arrhythmic and pump failure deaths, as well as improve functional capacity and quality of life. These therapies and the available supporting data relevant to pediatrics will be the focus of this review.

New-onset heart failure due to heart muscle disease in childhood: a prospective study in the United kingdom and Ireland

BACKGROUND

We undertook the first prospective, national, multicenter study to describe the incidence and outcome of heart muscle disease-induced heart failure in children.

METHODS AND RESULTS

Data were collected on patients admitted to a hospital through 2003 with a first episode of heart failure in the absence of congenital heart disease. All 17 pediatric cardiac centers in the United Kingdom and Ireland participated. Follow-up data were obtained to a minimum of 1 year. The incidence was 0.87/100,000 population <16 years (n=104; 53 girls; 95% confidence interval 0.71 to 1.05 per 100,000). Median age at presentation was 1 year, with 82% in New York Heart Association class III to IV. Causes of heart failure included dilated cardiomyopathy (50 idiopathic, 8 familial), probable myocarditis (23), occult arrhythmia (7), anthracycline toxicity (5), metabolic disease (4), left ventricular noncompaction (3), and other (4). Overall 1-year survival was 82%, and event (death or transplantation)-free survival was 66%. Regression analysis showed older age and reduced systolic function on admission echocardiogram increased the event risk. Only 8% of event-free survivors (n=69) remained in New York Heart Association class III to IV, but 35 required readmission during the study period, and all but 8 remained on medication.

CONCLUSIONS

This first national prospective study of new-onset heart failure in children has shown an incidence of 0.87/100,000. Multivariable analysis of survival data indicates a better outcome for younger children and for those with better systolic function at presentation, but overall, one third of children die or require transplantation within 1 year of presentation.

Outcome Predictors for Pediatric Dilated Cardiomyopathy: A Systematic Review

Dilated cardiomyopathy comprises the largest group of pediatric cardiomyopathy functional types and is the most common indication for heart transplant in children over 5 years old. Prognostic factors for this condition have long been sought by many researchers. In a systematic review of these factors, we found 32 relevant articles published since 1976. Four studies report finding no predictive factors. In the remaining 28 studies, several factors indicating better prognosis stand out across multiple articles: younger age at diagnosis, higher left-ventricular fractional shortening and ejection fraction, and the presence of myocarditis. Results for other factors conflict across studies: severe mitral regurgitation, arrhythmias, and a family history of cardiomyopathy. Elevated left-ventricular end diastolic pressure was statistically significant in two studies, but it may be of limited utility as a result of its invasiveness. Although most children have congestive heart failure at presentation, only two studies found it to be a significant predictor of mortality. The largest study of this factor qualified the increased risk to 1 year after presentation. Other significant predictors that have not been analyzed or reported by more than one study group, are right ventricular failure and impaired cardiac adrenergic innervation, as detected by radiolabeled meta-iodobenzylguanidine imaging. Although 1- and 5-year survival rates have steadily improved, as more children with DCM receive cardiac transplants, event-free survival rates (the absence of "heart death" resulting in death or transplant) are similar to those from decades ago. A unified risk algorithm may assist in clinical decision-making but requires more studies. Other studies are needed to assess the post-transplant survival experience.

Sudden death prior to pediatric heart transplantation: would implantable defibrillators improve outcome?

OBJECTIVES

The goal of this study is to determine the incidence of sudden cardiac death in children with cardiomyopathy prior to pediatric heart transplantation.

BACKGROUND

Recent primary prevention trials of implantable cardiac defibrillator (ICD) therapy in adults with ischemic and non-ischemic cardiomyopathy have shown a survival benefit. The incidence of sudden death, and thus the likelihood of improved survival with ICD therapy, in children with cardiomyopathy is currently unknown.

METHODS

The Pediatric Heart Transplant Study (PHTS) database was retrospectively queried for patients < or =18 years of age who died from any cause after listing for but prior to heart transplantation. Patients having arrhythmic or sudden death were included for study. Clinical and demographic variables were examined to identify higher-risk sub-groups.

RESULTS

Of the 2,392 patients in the PHTS database, 420 (17.6%) died prior to heart transplantation. Only 32 deaths (1.3% of total listed, 7.6% of total deaths) were sudden or arrhythmic in nature. Patients with ischemic cardiomyopathy had an increased risk of sudden death (relative risk = 6.92). Presence of congenital heart disease and United Network for Organ Sharing (UNOS) status at listing were not associated with an increased risk of sudden death.

CONCLUSIONS

The overall incidence of sudden death in children awaiting heart transplantation is low; therefore, uniform implantation of ICDs for the primary prevention of sudden death is unlikely to improve survival in this population. Children with ischemic cardiomyopathy appear to have a higher risk of sudden death and may benefit from ICD therapy.

Outcome factors of idiopathic dilated cardiomyopathy in children - a long-term follow-up review

BACKGROUND

Idiopathic dilated cardiomyopathy in children has a high rate of mortality. Cardiac transplantation is the treatment of choice in those who fail to respond to therapeutics. Several studies have been carried out to determine unfavourable prognoses, and to provide an early indication for cardiac transplantation. Nevertheless, no consensus has been reached on the matter.

OBJECTIVE

To propose predictors of death in children with idiopathic dilated cardiomyopathy.

METHODS

We reviewed data extending over 22 years from 142 consecutive children with idiopathic dilated cardiomyopathy, of whom 36 died. The criteria for inclusion were the presence of congestive heart failure or cardiomegaly in a routine chest X-ray, confirmed by enlargement and hypo kinesis of the left ventricle in the echocardiogram. We included asymptomatic children in functional class I. Based on Cox's analysis of clinical and laboratory data, we sought any predictors of death.

RESULTS

In univariate analysis, the predictors were functional class IV at presentation (p equal to 0.0001), dyspnoea (p equal to 0.0096), and reduced pedal pulses (p equal to 0.0413). In chest X-ray, they were maximal cardiothoracic ratio (p equal to 0.0001) and pulmonary congestion (p equal to 0.0072). In the electrocardiogram, right atrium overload (p equal to 0.0118), ventricular arrhythmias (p equal to 0.0148) and heart rate (p equal to 0.027). In the echocardiogram, mitral regurgitation of grade 3 to 4 (p equal to 0.002), the left atrial to aortic ratio (p equal to 0.0001), and left ventricle ejection fraction (p equal to 0.0266). In multivariate analysis, the independent predictors were maximum cardiothoracic ratio (p equal to 0.0001), left ventricle ejection fraction (p equal to 0.0013), mitral regurgitation of grade 3 or 4 (p equal to 0.0017), functional class IV at presentation (p equal to 0.0028), and ventricular arrhythmias (p equal to 0.0253).

CONCLUSION

Children, who have these predictors of death should be considered for early heart transplantation when no improvement is observed in clinical treatment.

Clinical features and outcomes of childhood dilated cardiomyopathy: results from a national population-based study

BACKGROUND

Despite considerable mortality, population-based prognostic factors for childhood dilated cardiomyopathy are lacking.

METHODS AND RESULTS

A population-based cohort study was undertaken of all children in Australia who presented with cardiomyopathy at age 0 to 10 years between January 1, 1987, and December 31, 1996. A single cardiologist analyzed all cardiac investigations, and a single pathologist analyzed histopathological material. There were 184 subjects with dilated cardiomyopathy. Positive viral identification or lymphocytic myocarditis was found in 30 (68.2%) of 44 cases with available early histology and 8 of 9 cases presenting with sudden death. Freedom from death or transplantation was 72% (95% CI, 65% to 78%) 1 year after presentation and 63% (95% CI, 55% to 70%) at 5 years. By proportional hazards regression analysis, risk factors for death or transplantation comprised age >5 years at presentation (hazard ratio 5.6, 95% CI, 2.6 to 12.0), familial dilated cardiomyopathy (hazard ratio, 2.9; 95% CI, 1.5 to 5.6), lower initial fractional shortening z score (hazard ratio per z-score unit, 0.75; 95% CI, 0.65 to 0.87), and failure to increase fractional shortening z score during follow-up (hazard ratio per unit increase, 0.68; 95% CI, 0.58 to 0.79). At follow-up, 78 (44.6%) of 175 cases diagnosed during life have no symptoms and are not taking any cardiac medication.

CONCLUSIONS

Early mortality is high in childhood dilated cardiomyopathy, but the clinical status of long-term survivors is good. This population-based study identifies children at risk of adverse events.

Presentation, management and outcomes of thrombosis for children with cardiomyopathy

BACKGROUND

Thrombosis in children with dilated and inflammatory cardiomyopathy is an unpredictable complication with potentially important morbidity.

OBJECTIVE

To determine the prevalence, associated factors, management and outcomes of thrombosis in this setting.

METHODS

Data were obtained from review of medical records. Factors associated with thrombosis and the impact on outcome were sought.

RESULTS

From 1990 to 1998, 66 patients that presented with dilated cardiomyopathy were followed for a median interval of 1.4 years (range 0 to 9.79 years) from first presentation. Thrombosis was diagnosed in four patients at presentation and in four patients during follow-up. Thrombosis was noted in one additional patient at examination after death. The overall nine-year period prevalence of thrombosis was 14%. Anticoagulation was started at presentation in 31% of patients. The mean left ventricular ejection fraction at presentation was significantly lower in those given anticoagulation (19+/-8%) versus those who were not (32+/-15%; P < 0.001). The mean ejection fraction at presentation was similar in those patients with (25+/-10%) versus those without thrombosis (28+/-15%; P = 0.44). During follow-up, 11 patients died and seven underwent cardiac transplantation. Kaplan-Meier estimates of freedom from death or transplantation were 88% at three months, 81% at one year and 70% at five years. Survival free of transplantation was not affected by thrombosis.

CONCLUSIONS

Thrombosis is common in children with cardiomyopathy, can occur at any time in the patients' clinical course and is not related to clinical features or survival free of transplantation. The relevance and prevention of thrombosis in this setting remains unclear.

Cardiac and clinical phenotype in Barth syndrome

OBJECTIVE

Barth syndrome, an X-linked disorder that is characterized by cardiomyopathy, neutropenia, skeletal myopathy, and growth delay, is caused by mutations in the taffazin gene at Xq28 that result in cardiolipin deficiency and abnormal mitochondria. The clinical phenotype in Barth syndrome has not been characterized systematically, and the condition may be underrecognized. We sought to evaluate extent of cardioskeletal myopathy, potential for arrhythmia, delays in growth, and biochemical correlates of disease severity in patients with this disorder.

METHODS

We conducted an observational, cross-sectional study of the largest cohort of patients with Barth syndrome to date (n = 34; age range: 1.2-22.6 years). Evaluation included echocardiography, electrocardiography (standard and signal-averaged), microvolt T wave alternans analysis, biochemical and hematologic laboratory analyses, and physical therapy evaluation of skeletal myopathy.

RESULTS

Family history was positive for confirmed or suspected Barth syndrome in 63%. Ninety percent of patients had a clinical history of cardiomyopathy (mean age at diagnosis of cardiomyopathy: 5.5 months; at genetic confirmation of Barth syndrome: 4.6 years). Echocardiography revealed a mean ejection fraction of 50% +/- 10%, mean fractional shortening of 28% +/- 5%, and mean left ventricular end-diastolic volume z score of 1.9 +/- 1.8. Left ventricular morphology demonstrated increased trabeculations or true noncompaction in 53%. Of 16 patients who were evaluated at > or = 11 years of age, 7 (43%) had documented ventricular arrhythmia. Growth deficiency was present (mean weight percentile: 15%; mean height percentile: 8%). Laboratory analysis revealed low total white blood cell count (absolute count: < 4000 cells per microL) in 25% of those who were not on granulocyte colony-stimulating factor. Hypocholesterolemia was present in 24%, decreased low-density lipoprotein cholesterol in 56%, low prealbumin in 79%, and mildly elevated creatine kinase in 15%.

CONCLUSIONS

Our cohort demonstrated clinical variability, but most had cardiomyopathy and diminished growth velocity, with a propensity toward neutropenia and low cholesterol. There was increased incidence of ventricular arrhythmia, predominantly in adolescents and young adults. Barth syndrome should be considered when boys present with cardiomyopathy, especially when associated with increased left ventricular trabeculations, neutropenia, skeletal muscle weakness, or family history indicating an X-linked pattern of inheritance.

Prospective single-arm protocol of carvedilol in children with ventricular dysfunction

The objective of this study was to evaluate the safety and efficacy of carvedilol in pediatric patients with stable moderate heart failure. We performed a single-arm prospective drug trial at three academic medical centers and the results were compared to historical controls. Patients were 3 months to 17 years old with an ejection fraction <40% in the systemic ventricle for at least 3 months on maximal medical therapy including ACE inhibitors. Treated patients were started on 0.1 mg/kg/day and uptitrated to 0.8 mg/kg/day or the maximal tolerated dose. Echocardiographic parameters of function were prospectively measured at entry and at 6 months. Two composite endpoints were recorded: severe decline in status and significant clinical change. Adverse events were reviewed by a safety committee. Data were also collected from untreated controls with dilated cardiomyopathy meeting entry criteria, assessed over a similar time frame. Twenty patients [12 dilated cardiomyopathy (DCM) and 8 congenital] with a median age of 8.4 years (range, 8 months to 17.8 years) were treated with carvedilol. Three patients discontinued the drug during the study. At entry, there was no statistical difference in age, weight, or ejection fraction between the treated group and controls. The ejection fraction of the treated DCM group improved significantly from entry to 6 months (median, 31 to 40%, p = 0.04), with no significant change in ejection fraction in the control group [median, 29 to 27%, p = not significant (NS)]. The median increase in ejection fraction was larger for the treated DCM group than for the untreated DCM controls (7 vs 0%, p = 0.05). By Kaplan-Meier analysis, time to death or transplant tended to be longer in treated patients (p = 0.07). The difference in the proportion of patients with severe decline in status or significant clinical change in the treated group was not significant compared to the controls (5 vs 12%, p = NS). We conclude that in this prospective protocol of pediatric patients, the use of adjunct carvedilol in the DCM group improved ejection fraction compared to untreated controls and trended toward delaying time to transplant or death.

QT intervals in metabolic dilated cardiomyopathy

OBJECTIVES

The present study determined the prevalence of dilated cardiomyopathy together with prolonged corrected QT (QTc) intervals in children. The study also examined whether an association exists between prolonged QTc intervals and ventricular dysrhythmia in a patient cohort with dilated cardiomyopathy.

BACKGROUND

The morbidity and mortality for pediatric patients with dilated cardiomyopathy remains high and is a clinical challenge. The patient population includes a significant number of Hutterite patients with metabolic disease associated with dilated cardiomyopathy.

METHODS

Thirty-eight pediatric patients with dilated cardiomyopathy were reviewed for the presence of prolonged QTc and dysrhythmias. Eleven patients had a metabolic etiology for their dilated cardiomyopathy.

RESULTS

Thirty-six per cent of the patient cohort had a long QTc interval. After 50 months of follow-up, the probability of survival for a child with a long QTc interval was approximately 50%. The probability of survival for a child with a normal QTc interval was 72%. Seventy per cent of the patients who died had a metabolic etiology for their dilated cardiomyopathy and a long QTc.

CONCLUSIONS

Dilated cardiomyopathy may be associated with a prolonged QTc and may increase the patient's risk for sudden death. The presence of a metabolic etiology for dilated cardiomyopathy increases the risk of death.

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.

Evolution of dilated cardiomyopathy (DCM) from idiopathic hypertrophic cardiomyopathy (IHCM) vs. inflammatory dilated cardiomyopathy (DCMi): a rare case of sudden death in an 8-year-old boy

In rare cases, the diagnosis of hypertrophic and dilated cardiomyopathy (DCM) in children was established postmortem. Our case report deals with the sudden and unexpected death of an 8-year-old boy. The postmortem examination revealed non-obstructive hypertrophy with irregular arrangement of muscular fibers, dilatation of the ventricles, endocardial fibrosis, microfocal vacuolization with enlarged hyperchromatic nuclei, and signs of inflammation with interstitial fibrosis. We present an evolution from idiopathic cardiomyopathy to DCM. To some extent, there were morphologic signs of an inflammatory process that first led us to suspect a specific inflammatory DCM.

The usefulness of surface electrocardiogram as a prognostic predictor in children with idiopathic dilated cardiomyopathy

We investigated the interrelations between surface electrocardiographic changes and clinical outcomes in children with idiopathic dilated cardiomyopathy (DCMP). 33 patients (19 boys, 14 girls) were classified into two groups; group I (15) who were in poor clinical status or dead; and group II (18) who showed good clinical status. Group I had larger LV dimensions compared to group II (Gr I vs. Gr II; LVEDD, 52 +/-11 vs. 42+/-7 (mm); LVESD, 43+/-12 vs. 30+/-5 (mm); p<0.05). QRS duration was prolonged in Gr I compared to Gr II and normal (Gr I, 84+/-28; Gr II, 66+/-12; normal control, 67+/-9). The QRS duration was correlated with the dimensions of left ventricle (LV). Corrected QT and JT interval and dispersions of QT in the DCMP group showed a significant difference compared to the normal control, however there was no significant difference between Gr I and II. In conclusion, QRS duration was correlated with ventricular dimension and clinical outcome in children with idiopathic dilated cardiomyopathy. Irrespective of increased ventricular inhomogeneity, QT dispersion could not be used to predict long-term prognosis.

Implications of ventricular arrhythmia vulnerability during murine electrophysiology studies

Programmed ventricular stimulation is being performed for the provocation of ventricular arrhythmias in genetically engineered mice. Despite the high level of interest in this area of translational research, little attention has been given to differentiating between selectivity and specificity of induced ventricular tachycardia (VT) in phenotypically normal mice. We aimed to assess factors that may enhance inducibility of VT in wild-type (WT) mice. In vivo intracardiac electrophysiological studies (EPS) were performed in 230 WT mice of 4 strains. An octapolar electrode catheter was inserted into a jugular vein and advanced to the right atrium and ventricle. Baseline ventricular conduction, refractoriness, and arrhythmia inducibility were assessed using programmed electrical stimulation (PES) and burst pacing. We found that nonsustained VT (> or =4 beats) was inducible in 68/230 (30%) mice. Duration of VT was 1.6 +/- 2.4 s, and the longest episode lasted 24 s. VT inducibility differed by strain and age. Ventricular effective refractory period (VERP) was shorter in mice with inducible VT (44 +/- 12 ms) compared with noninducible mice (61 +/- 16 ms, P < 0.001). VERP increased with age (P < 0.001), albeit with strain-related variability. We conclude that nonsustained VT in WT mice is reproducibly inducible and common. Genetic background variability may predispose certain strains to a higher incidence of arrhythmia induction. EPS methods impact prevalence and specificity of inducible VT. Increased VT inducibility was seen with shorter coupling intervals and application of tightly coupled extrastimuli techniques. These factors should be carefully considered when analyzing PES and burst pacing data in murine models to minimize false positives and optimize accuracy.

Delisting of infants and children from the heart transplantation waiting list after carvedilol treatment

OBJECTIVES

We performed a prospective, randomized, double-blind, placebo-controlled study of carvedilol effects in children with severe, chronic heart failure (HF), despite the use of conventional therapy.

BACKGROUND

Little is known about the effects of carvedilol in youngsters with chronic HF and severe left ventricular (LV) dysfunction.

METHODS

We conducted a double-blind, placebo-controlled study of 22 consecutive children with severe LV dysfunction. The children had chronic HF and left ventricular ejection fraction (LVEF) <30%. Patients were randomly assigned to receive either placebo (8 patients) or the beta-blocker carvedilol (14 patients) at 0.01 mg/kg/day titrated up to 0.2 mg/kg/day, followed-up for six months.

RESULTS

During the follow-up and the up-titration period in the carvedilol group, four patients died and one underwent heart transplantation. In patients receiving carvedilol evaluated after six months, a significant increase occurred in LVEF, from 17.8% (95% confidence interval [CI], 14.1 to 21.4%) to 34.6% (95% CI, 25.2 to 44.0%); p = 0.001. Modified New York Heart Association (NYHA) functional class improved in nine patients taken off the transplant waiting list. All nine patients were alive at follow-up. In the placebo group, during the six-month follow-up, two patients died, and two underwent heart transplantation. Four patients persisted with HF symptoms (NYHA functional class IV). No significant change occurred in LVEF or fractional shortening.

CONCLUSIONS

Carvedilol added to standard therapy may reduce HF progression and improve cardiac function, allowing some youngsters to be removed from the heart transplantation waiting list.

Diagnosis and management of pediatric myocarditis

Myocarditis is an insidious inflammatory disorder of the myocardium. As a clinical entity, it has been recognized for two centuries, but it defies traditional diagnostic tests. A greater understanding of the immune response underlying the pathobiology of the disorder can lead to a more rational therapeutic approach. The presentation, course and therapeutic options appear to be different in the pediatric compared with the adult population. An understanding of the difference between fulminant and acute progressive myocarditis has led to successful treatment strategies. A variety of new therapies are available, including antiviral agents, immunosuppression, and modulation of the biological response to inflammation. The specific question for patients with myocarditis is whether regimens designed to reduce or eliminate inflammation can provide clinical benefits compared with conventional heart failure therapy. This review highlights pathological mechanisms, modalities of diagnosis, and novel therapies which may improve outcomes.

Ventricular arrhythmia vulnerability in cardiomyopathic mice with homozygous mutant Myosin-binding protein C gene

BACKGROUND

Homozygous mutant mice expressing a truncated form of myosin-binding protein C (MyBP-C(t/t)) develop severe dilated cardiomyopathy, whereas the heterozygous mutation (MyBP-C(t/+)) causes mild hypertrophic cardiomyopathy. Adult male MyBP-C(t/t) and MyBP-C(t/+) mice were evaluated for arrhythmia vulnerability with an in vivo electrophysiology study.

METHODS AND RESULTS

Surface ECGs were obtained for heart rate, rhythm, and conduction intervals. Atrial, atrioventricular, and ventricular conduction parameters and refractoriness were assessed in 22 MyBP-C(t/t), 10 MyBP-C(t/+), and 17 wild-type MyBP-C(+/+) mice with endocardial pacing and intracardiac electrogram recording. Arrhythmia induction was attempted with standardized programmed stimulation at baseline and with isoproterenol. Heart rate variability and ambient arrhythmia activity were assessed with telemetric ECG monitors. Quantitative histological characterization was performed on serial sections of excised hearts. MyBP-C(t/t) and MyBP-C(t/+) mice have normal ECG intervals and sinus node, atrial, and ventricular conduction and refractoriness. Ventricular tachycardia was reproducibly inducible in 14 of 22 MyBP-C(t/t) mice (64%) during programmed stimulation, compared with 2 of 10 MyBP-C(t/+) mice (20%) and 0 of 17 wild-type controls (P<0.001). Ventricular ectopy was present only in MyBP-C(t/t) mice during ambulatory ECG recordings. There were no differences in heart rate variability parameters. Interstitial fibrosis correlated with genotype but did not predict arrhythmia susceptibility within the MyBP-C(t/t) group.

CONCLUSIONS

MyBP-C(t/t) mice, despite prominent histopathology and ventricular dysfunction, exhibit normal conduction and refractoriness, yet are vulnerable to ventricular arrhythmias. Somatic influences between genetically identical mutant mice most likely account for variability in arrhythmia susceptibility. A sarcomeric protein gene mutation leads to a dilated cardiomyopathy and ventricular arrhythmia vulnerability phenotype.

Clinical, electrocardiographic, and histologic correlations in children with dilated cardiomyopathy

OBJECTIVE

To determine whether presenting electrocardiography is related to histologic findings and clinical outcomes in children with dilated cardiomyopathy.

BACKGROUND

Lymphocytic myocarditis is an important cause of childhood dilated cardiomyopathy, the outcome of which is unclear. The results of non-invasive investigations are often used to infer the presence or absence of lymphocytic myocarditis.

METHODS

Thirty-four children, presenting acutely with dilated cardiomyopathy, underwent both early electrocardiography and endomyocardial biopsy. The parameters examined included heart rate, PR, QRS, and corrected QT intervals, R-wave voltages in Leads V(1) and V(6), S-wave voltages in Leads V(1) and V(6), and sum of SV(1) and RV(6). We expressed measurements as Z scores, based on published normal values for age and gender.

RESULTS

A total of 15 patients had lymphocytic myocarditis on endomyocardial biopsy (Group I), and 19 had non-specific histologic findings (Group II). We did not distinguish the 2 groups by age, time to endomyocardial biopsy, or duration of follow-up. Group I patients had significantly smaller R-wave Z scores in Leads V(1) and V(6), and combined S in V(1) and R in V(6) Z scores (p < 0.02 for each). The positive and negative predictive values of an R-wave amplitude in V(6) < 5th percentile were 75% and 65%, respectively, for the diagnosis of lymphocytic myocarditis. An R-wave amplitude in V(6) > 95th percentile had a positive and negative predictive value of 80% and 63%, respectively, for the diagnosis of idiopathic dilated cardiomyopathy. Survival and freedom from late cardiac dysfunction were more common among Group I patients compared with Group II (p <or= 0.02 for both).

CONCLUSION

Myocardial histology cannot reliably be inferred from the presenting electrocardiogram. Survival and outcome for children with lymphocytic myocarditis is better than for those with non-specific histology.

Impaired cardiac adrenergic innervation assessed by MIBG imaging as a predictor of treatment response in childhood dilated cardiomyopathy

OBJECTIVE

To evaluate the prognostic value of metaiodobenzylguanidine (MIBG) imaging in childhood cardiomyopathy.

DESIGN

Prospective cohort study.

SETTING

Tertiary referral centre.

PATIENTS

40 children (21 boys, 19 girls; mean (SD) age, 7.0 (5.6) years) with heart failure resulting from idiopathic dilated cardiomyopathy (n = 23) or various other disorders (n = 17).

METHODS

At the initial examination, cardiac (123)I-MIBG uptake and release, circulating noradrenaline (norepinephrine) concentration, x ray cardiothoracic ratio, and echocardiographic variables were recorded. Cardiac MIBG uptake was obtained by measuring the heart to mediastinum activity ratio on the planar image obtained four hours after MIBG injection. MIBG washout rate was evaluated using relative decrease in cardiac activity measured at 20 minutes and four hours. Patients were treated with angiotensin converting enzyme inhibitors, diuretics, and digitalis, and were followed up for 12 (10) months. Fifteen patients did not respond to medical treatment (12 heart transplants; three deaths), and 25 did respond (improved or stable).

RESULTS

Cardiac MIBG uptake was positively correlated with x ray cardiothoracic index (r = 0.55, p = 0.0008) and echocardiographic left ventricular fractional shortening (r = 0.68, p < 0.0001). Among all the clinical and laboratory variables tested, multivariate discriminant analysis showed that the only independent predictor of an unfavourable outcome was a low MIBG uptake (p < 0.001). Survival curves had a mean threshold value of 1.54 for MIBG uptake.

CONCLUSIONS

Impaired cardiac adrenergic innervation is strongly related to adverse outcome in children with dilated cardiomyopathy, independently of the aetiology. MIBG imaging may help to stratify risk in such patients.

The outcome of idiopathic dilated cardiomyopathy and myocarditis in children from the west of Scotland

We analysed retrospectively all infants and children with idiopathic dilated cardiomyopathy (IDC) and myocarditis at the Regional Cardiac Centre of the Royal Hospital for Sick Children, Glasgow, during 1980-1997. Among the 39 patients with IDC, 25 (64%) were infants aged < 1 year, eight (20.5%) had wheezing as the presenting symptom, and only six (15%) had a significant cardiac murmur. Thirty-eight of thirty-nine patients diagnosed in life were followed-up for 1 day to 15 years (median 3 years). Twelve of the thirty-nine (31%) died, six deaths were within a week of presentation and the rest within a year. The survival at 1 year and at 12 years was 0.69 (95% CI 0.54 to 0.84). Fourteen patients had histologically proven myocarditis, and all 9/14 (64%) detected at post-mortem and one of the five diagnosed in life died. Patients with myocarditis exhibited an actuarial survival of 0.29 (95% CI 0.04 to 0.53) at 1 year and at 9 years, significantly lower than IDC patients (log rank 9.8, P < 0.01). There was no difference in the outcome for patients with positive or negative Coxsackie titres or who presented in the 1980s and in the 1990s. No risk factor that independently influenced the outcome or survival could be identified in either group. Thus our study from a relatively well-defined population of the west of Scotland showed that a significant proportion of children with IDC and myocarditis died in the first week of illness and that patients with myocarditis had shorter survival.

Evidence for autosomal recessive inheritance of infantile dilated cardiomyopathy: studies from the Eastern Province of Saudi Arabia

Familial dilated cardiomyopathy is being increasingly recognized, but affected individuals <10 y are rarely identified. We describe the natural history of dilated cardiomyopathy and evaluate the mode of inheritance among infants of Arab descent from the Eastern Province of Saudi Arabia. We evaluated 55 consecutive cases of dilated cardiomyopathy in patients <10 y of age seen during a 5-y interval. Echocardiography was the primary diagnostic modality. The 55 cases represented 20% of the offspring of 41 families of Arab descent. In 19 families (46%), parents were first cousins; there was no obvious consanguinity in 22 families (54%). Age at presentation was <30 mo (95%) (range, 1 to 100 mo); males (38%) and females (62%) were affected. Patients died (25 patients, 46%), improved (15 patients, 27%), or recovered (15 patients, 27%). The left ventricular shortening fraction at diagnosis ranged from 5 to 28% and did not differ in those who died, improved, or recovered. Complex segregation analysis of the family data using the mixed model of inheritance showed that a model of recessive inheritance best fits the data. Recessively inherited dilated cardiomyopathy has been infrequently reported, perhaps because it may be difficult to recognize in other patient groups in which consanguineous marriage is uncommon and the number of children per family is small. In the setting of consanguineous marriage, homozygosity mapping should lead to identification of the gene(s) causing dilated cardiomyopathy in the families we studied.

Outcomes for children with cardiomyopathy awaiting transplantation

OBJECTIVE

To determine factors associated with outcomes after listing for transplantation in children with cardiomyopathies.

BACKGROUND

Childhood cardiomyopathies form a heterogeneous group of diseases, and in many, the prognosis is poor, irrespective of the etiology. When profound heart failure develops, cardiac transplantation can be the only viable option for survival.

METHODS

We included all children with cardiomyopathy listed for transplantation between 12/89 and 4/98 in this historical cohort study.

RESULTS

We listed 31 patients, 15 male and 16 female, 27 with dilated and 4 with restrictive cardiomyopathy, for transplantation. The median age at listing was 5.7 years, with a range from fetal life to 17.8 years. Transplantation was achieved in 23 (74%), with a median interval from listing of 54 days, and a range from zero to 11.4 years. Of the patients, 14 were transplanted within 30 days of listing. Five patients (16%) died before transplantation. Within the Canadian algorithm, one of these was in the third state, and four in the fourth state. One patient was removed from the list after 12 days, having recovered from myocarditis, and two remain waiting transplantation after intervals of 121 and 476 days, respectively. Patients who died were more likely to be female (5/5 vs. 11/26; p=0.04) and to have been in the third or fourth states at listing (5/5 vs. 15/26; p=0.04). The use of mechanical ventricular assistance, in 10 patients, was not a predictor of an adverse outcome. While not statistically significant, survival to transplantation was associated with treatment using inhibitors of angiotensin converting enzyme, less mitral regurgitation, a higher mean ejection fraction and cardiac index, and lower right ventricular systolic pressure.

CONCLUSIONS

Children with cardiomyopathy awaiting transplantation have a mortality of 16% related to their clinical state at the time of listing.

Genetic abnormalities responsible for dilated cardiomyopathy

Dilated cardiomyopathy (DCM), a disorder in which left ventricular dilation and dysfunction leads to congestive heart failure, is inherited in over 30% of cases. The underlying genetic mechanisms are slowly being unraveled, with multiple genes recently identified as causing DCM in some patients. The genes identified to date appear to encode proteins that either support the cytoskeleton or interact with the cytoskeleton. When mutated, these proteins destabilize the cardiomyocyte membrane or cytoskeleton via mechanical instability or force transduction causing poor cardiac systolic function and compensatory dilation. Once the entire group of genes causing DCM (genetic heterogeneity) are identified, improvements in diagnosis and treatment are expected.

Design and implementation of the North American Pediatric Cardiomyopathy Registry

The Pediatric Cardiomyopathy Registry (PCMR) was established to describe the epidemiologic features and clinical course of selected cardiomyopathies in patients aged 18 years or younger and to promote the development of etiology-specific treatments. Sixty-one private and institutional pediatric cardiomyopathy practices in the United States and Canada were recruited to participate in the PCMR. The registry consists of a prospective, population-based cohort of patients in 2 regions (New England and the Central Southwestern United States) and a retrospective cohort of patients diagnosed between 1991 and 1996. Annual follow-up data are collected on all patients. As of June 1999, the PCMR consisted of 337 prospectively identified and 990 retrospectively identified patients. The PCMR has demonstrated the feasibility of establishing a large database of sociodemographic and clinical information on children with pediatric cardiomyopathy. Through this cooperative effort, the PCMR will obtain precise estimates of the incidence of pediatric cardiomyopathy and a better understanding of the natural history of this disease.

Familial carnitine transporter defect: A treatable cause of cardiomyopathy in children

Carnitine transporter defect is characterized by severely reduced transport of carnitine into skeletal muscle, fibroblasts, and renal tubules. All children with dilated cardiomyopathy or hypoglycemia and coma should be evaluated for this transporter defect because it is readily amenable to therapy that results in prolonged prevention of cardiac failure. This article details the cases of 3 children who have carnitine transporter defect, 2 of whom had severe dilated cardiomyopathy. Plasma and skeletal muscle carnitine levels were extremely low and both children were treated with oral L-carnitine, resulting in resolution of severe cardiomyopathy and prevention of recurrence or cardiac enlargement for more than 5 years. The third child had hypoglycemia and coma as presenting findings of the transporter defect and had mild left ventricular hypertrophy but no cardiac failure. The prognosis for long-term survival in pediatric dilated cardiomyopathy is poor. Children with carnitine transporter defect can have a different outcome if their underlying condition is detected early and treated medically.

Heart transplantation in children: indications. Report of the Ad Hoc Subcommittee of the Pediatric Committee of the American Society of Transplantation (AST)

This review details the indications for heart transplantation in children. Contraindications have evolved from absolute to relative. Controversial issues remain and this paper represents a consensus of more than a dozen centers that have programs that remain active performing pediatric heart transplants.