Cardiac Involvement in Classical Organic Acidurias: Clinical Profile and Outcome in a Pediatric Cohort

BACKGROUND

Cardiac involvement is reported in a significant proportion of patients with classical organic acidurias (OAs), contributing to disability and premature death. Different cardiac phenotypes have been described, among which dilated cardiomyopathy (DCM) is predominant. Despite recent progress in diagnosis and treatment, the natural history of patients with OAs remains unresolved, specifically with regard to the impact of cardiac complications. We therefore performed a retrospective study to address this issue at our Referral Center for Pediatric Inherited Errors of Metabolism.

METHODS

Sixty patients with OAs (propionic (PA), methylmalonic (MMA) and isovaleric acidemias and maple syrup urine disease) diagnosed from 2000 to 2022 were systematically assessed at baseline and at follow-up.

RESULTS

Cardiac anomalies were found in 23/60 OA patients, all with PA or MMA, represented by DCM (17/23 patients) and/or acquired long QT syndrome (3/23 patients). The presence of DCM was associated with the worst prognosis. The rate of occurrence of major adverse cardiac events (MACEs) at 5 years was 55% in PA with cardiomyopathy; 35% in MMA with cardiomyopathy; and 23% in MMA without cardiomyopathy. Liver transplantation was performed in seven patients (12%), all with PA or MMA, due to worsening cardiac impairment, and led to the stabilization of metabolic status and cardiac function.

CONCLUSIONS

Cardiac involvement was documented in about one third of children diagnosed with classical OAs, confined to PA and MMA, and was often associated with poor outcome in over 50%. Etiological diagnosis of OAs is essential in guiding management and risk stratification.

Focus on Paediatric Restrictive Cardiomyopathy: Frequently Asked Questions

Restrictive cardiomyopathy (RCM) is characterized by restrictive ventricular pathophysiology determined by increased myocardial stiffness. While suspicion of RCM is initially raised by clinical evaluation and supported by electrocardiographic and echocardiographic findings, invasive hemodynamic evaluation is often required for diagnosis and management of patients during follow-up. RCM is commonly associated with a poor prognosis and a high incidence of heart failure, and PH is reported in paediatric patients with RCM. Currently, only a few therapies are available for specific RCM aetiologies. Early referral to centres for advanced heart failure treatment is often necessary. The aim of this review is to address questions frequently asked when facing paediatric patients with RCM, including issues related to aetiologies, clinical presentation, diagnostic process and prognosis.

Aortic Dilatation in Pediatric Patients with Bicuspid Aortic Valve: How the Choice of Nomograms May Change Prevalence

BACKGROUND

Aortic dilation (AoD) is commonly reported in patients with bicuspid aortic valve (BAV) and has been related to flow abnormalities and genetic predisposition. AoD-related complications are reported to be extremely rare in children. Conversely, an overestimate of AoD related to body size may lead to excess diagnoses and negatively impact quality of life and an active lifestyle. In the present study, we compared the diagnosis performance of the newly introduced Q-score (based on a machine-learning algorithm) versus the traditional Z-score in a large consecutive pediatric cohort with BAV.

MATERIALS AND METHODS

Prevalence and progression of AoD were evaluated in 281 pediatric patients ages > 5 and < 18 years at first observation, 249 of whom had isolated BAV and 32 had BAV associated with aortic coarctation (CoA-BAV). An additional group of 24 pediatric patients with isolated CoA was considered. Measurements were made at the level of the aortic annulus, Valsalva sinuses, sinotubular aorta, and proximal ascending aorta. Both Z-scores using traditional nomograms and the new Q-score were calculated at baseline and at followup (mean 4.5 years).

RESULTS

A dilation of the proximal ascending aorta was suggested by traditional nomograms (Z-score > 2) in 31.2% of patients with isolated BAV and 18.5% with CoA-BAV at baseline and in 40.7% and 33.3%, respectively, at followup. No significant dilation was found in patients with isolated CoA. Using the new Q-score calculator, ascending aorta dilation was detected in 15.4% of patients with BAV and 18.5% with CoA-BAV at baseline and in 15.8% and 3.7%, respectively, at followup. AoD was significantly related to the presence and degree of aortic stenosis (AS) but not to aortic regurgitation (AR). No AoD-related complications occurred during the followup.

CONCLUSIONS

Our data confirm the presence of ascending aorta dilation in a consistent subgroup of pediatric patients with isolated BAV, with progression during followup, while AoD was less common when CoA was associated with BAV. A positive correlation was found with the prevalence and degree of AS, but not with AR. Finally, the nomograms used may significantly influence the prevalence of AoD, especially in children, with a possible overestimation by traditional nomograms. This concept requires prospective validation in long-term followup.

Real-World Use and Predictors of Response to Disopyramide in Patients with Obstructive Hypertrophic Cardiomyopathy

Background: Although disopyramide has been widely used to reduce left ventricular outflow obstruction (LVOTO) and to improve symptoms in patients with obstructive hypertrophic cardiomyopathy (oHCM), its use in real world as well as patient characteristics associated with a positive treatment response are still unclear. Methods: From 1980 to 2021, 1527 patients with HCM were evaluated and 372 (23%) had a LVOTO with active follow-up. The efficacy and safety of disopyramide were assessed systematically during 12 months (2-, 6-, and 12-month visits). Responders were patients with a final NYHA = I and a LVOTO < 30 mmHg; incomplete responders were those patients with NYHA > I and a LVOTO < 30 mmHg; and non-responders were symptomatic patients with no change in functional class NYHA and a LVOT gradient > 30 mmHg. Results: Two-hundred-fifty-four (66%) patients were in functional class NYHA I/II and 118 (34%) in NYHA III/IV. A total of 118/372 (32%, 55 ± 16 years) underwent disopyramide therapy. Twenty-eight (24%) patients responded to therapy, 39 (33%) were incomplete responders, and 51 (43%) did not respond. Responder were mainly patients in functional NYHA class I/II (24/28, 86%), whereas incomplete responders and non-responders were more often in functional NYHA class III/IV (50/54 (93%)). An independent predictor of response to disopyramide treatment was the presence of NYHA I/II at the initiation of therapy (HR 1.5 (95% CI 1.1–4.5), p = 0.03). No major life-threatening arrhythmic events or syncope occurred, despite 19 (16%) patients showing reduced QTc from baseline, 19 (16%) having no difference, while 80 (69%) patients had prolonged QTc interval. Thirty-one (26%) patients experienced side effects, in particular, 29 of the anticholinergic type. Conclusions: Disopyramide was underused in oHCM but effective in reducing LVOTO gradients and symptoms in slightly symptomatic patients with less severe disease phenotype with a safe pro-arrhythmic profile.

Genetic Testing and Counselling in Hypertrophic Cardiomyopathy: Frequently Asked Questions

Genetic counselling and genetic testing in hypertrophic cardiomyopathy (HCM) represent an integral part of the diagnostic algorithm to confirm the diagnosis, distinguish it from phenocopies, and suggest tailored therapeutic intervention strategies. Additionally, they enable cascade genetic testing in the family. With the implementation of Next Generation Sequencing technologies (NGS), the interpretation of genetic data has become more complex. In this regard, cardiologists play a central role, aiding geneticists to correctly evaluate the pathogenicity of the identified genetic alterations. In the ideal setting, geneticists and cardiologists must work side by side to diagnose HCM as well as convey the correct information to patients in response to their many questions and concerns. After a brief overview of the role of genetics in the diagnosis of HCM, we present and discuss the frequently asked questions by HCM patients throughout our 20-year genetic counselling experience. Appropriate communication between the team and the families is key to the goal of delivering the full potential of genetic testing to our patients.

Clinical profile and outcome of cardiomyopathies in infants and children seen at a tertiary centre

INTRODUCTION

Due to their rare prevalence and marked heterogeneity, pediatric cardiomyopathies (CMPs) are little known and scarcely reported. We report the etiology, clinical profile and outcome of a consecutive cohort of children diagnosed with CMP and followed at Meyer Children's Hospital over a decade.

PATIENTS AND METHODS

We retrospectively reviewed patients consecutively referred from May 2008 to May 2019 for pediatric onset CMP (<18 years). Heart disease caused by arrhythmic disorders, toxic agents, rheumatic conditions and maternal disease were excluded.

RESULTS

We enrolled 110 patients (65 males), diagnosed at a median age of 27 [4-134] months; 35% had an infant onset (<1 year of age). A positive family history was more often associated with childhood-onset (38.8%). Hypertrophic cardiomyopathy (HCM; 48 patients) was the most frequent phenotype, followed by dilated cardiomyopathy (DCM; 35 patients). While metabolic and idiopathic etiologies were preponderant in infants, metabolic and sarcomeric diseases were most frequent in the childhood-onset group. Major adverse cardiac events (MACE) occurred in 31.8% of patients, including hospitalization for acute heart failure in 25.5% of patients, most commonly due to DCM. Overall, the most severe outcomes were documented in patients with metabolic diseases.

CONCLUSIONS

In a consecutive cohort of pediatric patients with CMP, those with infantile onset and with a metabolic etiology had the worst prognosis. Overall, MACE occurred in 41% of the entire population, most commonly associated with DCM, inborn errors of metabolism and genetic syndromes. Systematic NGS genetic testing was critical for etiological diagnosis and management.

Safety and efficacy of ranolazine in hypertrophic cardiomyopathy: Real-world experience in a National Referral Center

OBJECTIVES

We assessed the efficacy and safety of ranolazine in real-world patients with hypertrophic cardiomyopathy (HCM).

BACKGROUND

Ranolazine is an anti-anginal drug that inhibits the late phase of the inward sodium current. In a small prospective trial, ranolazine reduced the arrhythmic burden and improved biomarker profile in HCM patients. However, systematic reports reflecting real-world use in this setting are lacking.

METHODS

Changes in clinical and instrumental features, symptoms and arrhythmic burden were evaluated in 119 patients with HCM before and during treatment with ranolazine at a national referral centre for HCM.

RESULTS

Patients were treated with ranolazine for 2 [1-4] years; 83 (70%) achieved a dosage ≥1000 mg per day. Treatment interruption was necessary in 24 patients (20%) due to side effects (n = 10, 8%) or disopyramide initiation (n = 8, 7%). Seventy patients (59%) were treated with ranolazine for relief of angina. Among them, 51 (73%) had total symptomatic relief and 47 patients (67%) showed ≥2 Canadian Cardiovascular society (CCS) angina grade improvement. Sixteen patients (13%) were treated for recurrent ventricular arrhythmias, including 4 with a clear ischemic trigger, who experienced no further arrhythmic episodes while on ranolazine. Finally, 33 patients (28%) were treated for heart failure associated with severe diastolic dysfunction: no symptomatic benefit could be observed in this group.

CONCLUSION

Ranolazine was safe and well tolerated in patients with HCM. The use of ranolazine may be considered in patients with HCM and microvascular angina.

263 GENETIC CAUSES OF CARDIOMYOPATHIES IN CHILDREN

Background

The genetic background of paediatric cardiomyopathies is only partially resolved, because of their rarity and heterogeneity. However, the assessment of aetiology is of paramount importance in order to define prognosis and therapeutic choices. Moreover, the recognition of genetic causes is the basis for cascade screening in the family.

Aims

This study aimed to identify the genetic causes of cardiomyopathies in children evaluated and followed at our paediatric hospital.

Methods

A validated Next Generation Sequencing (NGS) target panel was performed in a cohort of 76 paediatric patients: 36 Hypertrophic Cardiomyopathy, (HCM), 24 Dilated Cardiomyopathy (DCM), 3 Restrictive Cardiomyopathy (RCM), 2 Left Ventricular Non Compaction (LVNC), 10 Arrhythmogenic Cardiomyopathy (AC) and one with a cardiac arrest. Genetic counselling was offered to parents. Furthermore, 9 patients with negative genes panel were selected for Whole Exome Sequencing (WES).

Results

By target genes panel analysis we identified a pathogenic or likely pathogenic variant in 32/76 patients (42%). Most genotyped patients had a sarcomeric aetiology and MYH7 (11/32, 34%), MYBPC3 (7/32, 22%) and thin-filaments genes (9/32, 28%) resulted the most mutated genes. 11/32 (34%) patients had a complex genotype. In one patient we found the rare coexistence of two independent monogenic diseases (Osteogenesis Imperfecta and HCM) due respectively to COL1A1 and MYH7 variants. Moreover, we identified five syndromic cases (5/32, 16%): three patients with Noonan Syndrome (one with SOS1 variant and two with PTPN11 variants), one boy with Danon Disease (with LAMP2 variant) and a newborn with Alström Syndrome (due to ALMS1 variants). By WES we identified a de novo variant in FLNC gene in a 7 years old child RCM, a Noonan Syndrome due to biallelic LZTR1 variants in a 9 years old child, two PLEC1 variants in a newborn with DCM and Epidermolysis bullosa, and a de novo NKX2-5 variant in a child with RCM.

Conclusions

A definitive molecular diagnosis could be obtained in a substantial proportion of children (42%). The genetic test results had direct implications for clinical management, to suggest therapeutic interventions. Moreover, predictive genetic testing in family members resulted very important for clinical follow-up and to establish the recurrence risk for subsequent pregnancies.

[Clinical pathway on pediatric cardiomyopathies: a genetic testing strategy proposed by the Italian Society of Pediatric Cardiology]

Pediatric cardiomyopathies are rare diseases, heterogeneous in clinical presentation, etiology and prognosis. Etiological diagnosis, where genetic analysis plays a key role, is of fundamental importance for defining diagnostic and therapeutic pathways. Furthermore, the identification of the genetic substrate represents a prerequisite for cascade screening in the proband's family members and to allow conscious reproductive choices. To date, genetic testing is performed with the analysis of gene panels (targeted panels) or with the study of the entire exome (whole exome sequencing) using next generation sequencing (NGS) technology. The great genetic heterogeneity and the temporal variability of the clinical manifestations lead to unique problems for pediatric cardiomyopathies, distinct from those of the adult, such as the possible indications for access to the test, the type of test to be used (exome or panel of genes), the importance of analyzing parents, especially in cases with neonatal onset; moreover, the correct execution of bioinformatics analysis and the interpretation of NGS data play a crucial role in the impact of the results on clinical management.

Clinical presentation and long-term outcomes of infantile hypertrophic cardiomyopathy: a European multicentre study

AIMS

Children presenting with hypertrophic cardiomyopathy (HCM) in infancy are reported to have a poor prognosis, but this heterogeneous group has not been systematically characterized. This study aimed to describe the aetiology, phenotype, and outcomes of infantile HCM in a well-characterized multicentre European cohort.

METHODS AND RESULTS

Of 301 children diagnosed with infantile HCM between 1987 and 2019 presenting to 17 European centres [male n = 187 (62.1%)], underlying aetiology was non-syndromic (n = 138, 45.6%), RASopathy (n = 101, 33.6%), or inborn error of metabolism (IEM) (n = 49, 16.3%). The most common reasons for presentation were symptoms (n = 77, 29.3%), which were more prevalent in those with syndromic disease (n = 62, 61.4%, P < 0.001), and an isolated murmur (n = 75, 28.5%). One hundred and sixty-one (53.5%) had one or more co-morbidities. Genetic testing was performed in 163 (54.2%) patients, with a disease-causing variant identified in 115 (70.6%). Over median follow-up of 4.1 years, 50 (16.6%) underwent one or more surgical interventions; 15 (5.0%) had an arrhythmic event (6 in the first year of life); and 48 (15.9%) died, with an overall 5 year survival of 85%. Predictors of all-cause mortality were an underlying diagnosis of IEM [hazard ratio (HR) 4.4, P = 0.070], cardiac symptoms (HR 3.2, P = 0.005), and impaired left ventricular systolic function (HR 3.0, P = 0.028).

CONCLUSIONS

This large, multicentre study of infantile HCM describes a complex cohort of patients with a diverse phenotypic spectrum and clinical course. Although overall outcomes were poor, this was largely related to underlying aetiology emphasizing the importance of comprehensive aetiological investigations, including genetic testing, in infantile HCM.

The Influence of Genotype on the Phenotype, Clinical Course, and Risk of Adverse Events in Children with Hypertrophic Cardiomyopathy

Genetic testing in children with hypertrophic cardiomyopathy (HCM) can modify clinical management and lifestyle counseling. However, predicting long-term outcome and response to management in individual patients remains challenging, because of the peculiar genetic heterogeneity of the disease in the pediatric age range. Children with HCM secondary to an inborn error of metabolism or malformation syndromes tend to have a worse outcome compared with those with the classic sarcomeric form. Among the latter, adverse genetic features are represented by the identification of a pathogenic variant in MYH7, often associated with severe hypertrophy, a complex genotype, or a de novo variant.

Diagnosis and Management of Cardiovascular Involvement in Friedreich Ataxia

Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder caused by a homozygous GAA triplet repeat expansion in the frataxin gene. Cardiac involvement, usually manifesting as hypertrophic cardiomyopathy, can range from asymptomatic cases to severe cardiomyopathy with progressive deterioration of the left ventricular ejection fraction and chronic heart failure. The management of cardiac involvement is directed to prevent disease progression and cardiovascular complications. However, direct-disease therapies are not currently available for FRDA. The present review aims to describe the current state of knowledge regarding cardiovascular involvement of FRDA, focusing on clinical-instrumental features and management of cardiac manifestation.

Hidden familial cardiomyopathies in children: Role of genetic testing

Pediatric cardiomyopathies harbour significant phenotypic and genetic heterogeneity. Genetic testing is essential for the initial evaluation and the ongoing care of child and family, although challenges remain regarding its appropriate clinical implementation in minors. We here discuss the key role of genetic diagnosis in the clinical management of two patients.

The role of the electrocardiographic phenotype in risk stratification for sudden cardiac death in childhood hypertrophic cardiomyopathy

AIMS

The 12-lead electrocardiogram (ECG) is routinely performed in children with hypertrophic cardiomyopathy (HCM). An ECG risk score has been suggested as a useful tool for risk stratification, but this has not been independently validated. This aim of this study was to describe the ECG phenotype of childhood HCM in a large, international, multi-centre cohort and investigate its role in risk prediction for arrhythmic events.

METHODS AND RESULTS

Data from 356 childhood HCM patients with a mean age of 10.1 years (±4.5) were collected from a retrospective, multi-centre international cohort. Three hundred and forty-seven (97.5%) patients had ECG abnormalities at baseline, most commonly repolarization abnormalities (n = 277, 77.8%); left ventricular hypertrophy (n = 240, 67.7%); abnormal QRS axis (n = 126, 35.4%); or QT prolongation (n = 131, 36.8%). Over a median follow-up of 3.9 years (interquartile range 2.0-7.7), 25 (7%) had an arrhythmic event, with an overall annual event rate of 1.38 (95% CI 0.93-2.04). No ECG variables were associated with 5-year arrhythmic event on univariable or multivariable analysis. The ECG risk score threshold of >5 had modest discriminatory ability [C-index 0.60 (95% CI 0.484-0.715)], with corresponding negative and positive predictive values of 96.7% and 6.7.

CONCLUSION

In a large, international, multi-centre cohort of childhood HCM, ECG abnormalities were common and varied. No ECG characteristic, either in isolation or combined in the previously described ECG risk score, was associated with 5-year sudden cardiac death risk. This suggests that the role of baseline ECG phenotype in improving risk stratification in childhood HCM is limited.

[Bicuspid aortic valve and associated aortopathy: from clinical examination to advanced multimodality imaging]

Bicuspid aortic valve (BAV) is the most common congenital heart disease, affecting 0.5-2% of the general population. It is often associated with aortopathy with aneurysmal dilation of the ascending aorta (AA). Up to 75% of patients with coarctation of the aorta (CoA) present with BAV and its diagnosis is crucial because it can increase the risk for aortic complications. CoA is a cardiac malformation that can be undiagnosed until old age with only hypertension as a marker of its presence.We present the case of an asymptomatic 17-year-old boy who underwent regular visit for competitive sports activity. During a treadmill test he showed a hypertensive response to effort and the echocardiogram diagnosed a normally functioning BAV associated with AA dilation. The clinical suspicion of CoA was confirmed by a complete echocardiogram, and the patient underwent catheter-based invasive aortography and the CoA was treated with angioplasty and stenting. Few years after the interventional procedure, he performed a thoracic computed tomography that showed an increased aortic dilation at the level of the Valsalva sinus and the AA. The patient underwent surgical aortic repair using the David technique. At present, the patient continues a close follow-up with advanced cardiac imaging (including cardiac magnetic resonance) for BAV surveillance and accurate detection of all aortic measures.

[Clinical pathway for cardiomyopathies: a genetic testing strategy proposed by ANMCO in Tuscany]

Hereditary cardiomyopathies, hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic cardiomyopathy, restrictive cardiomyopathy and left ventricular noncompaction, are clinically and genetically very heterogeneous diseases, and they represent a frequent cause of cardiac arrest and sudden death. To date, over 100 genes are known to be associated with the onset of cardiomyopathies. Genetic testing is performed by next generation sequencing, a technology that has made it possible to analyze hundreds of genes in many patients simultaneously, shortening costs and execution times. However, with the use of this technology, new problems have arisen regarding the indications for access to the test, the interpretation of the data and the clinical implications of the results.This document aims to represent an operational support tool for hospital cardiologists to make the use of genetic testing more accessible and appropriate for their patients with suspected or ascertained hereditary cardiomyopathy.

A rare case of pediatric cardiomyopathy: Alström syndrome identified by gene panel analysis

Genetic investigation of early-onset Dilatative cardiomyopathy phenotype, including molecular autopsy, is the key to appropriate recognition and management of rare etiologies and atypical presentations and to offer genetic counseling to the family.

Prevalence of adverse cardiovascular events in pediatric cardiomyopathies: an analysis of 110 patients followed at a long-standing tertiary care paediatric centre

Introduction

Pediatric cardiomyopathies (CMP) are disorders of the morphology and function of the heart, with a greater heterogeneity concerning etiology and clinical presentation than adult CMP. The assessment of etiology and genetic status is of paramount importance for prognosis, family screening, and therapeutic choices.

Purpose

To report clinical presentation, etiology, and outcome of a cohort of children diagnosed with CMP followed at tertiary care pediatric referral centre.

Methods

We retrospectively reviewed clinical, laboratory and imaging data of all patients referred to our cardiomyopathy centre from May 2008 to May 2019 for pediatric CMP (&lt;18 years). CMP due to arrhythmic disorders, toxic agents' exposure, rheumatic conditions and maternal disease (i.e. maternal diabetes) were excluded. Primary endpoint was a composite of major adverse cardiovascular events (MACE: cardiovascular death, heart failure [HF] hospitalization, arrhythmic events, need for surgery or heart transplant referral).

Results

We enrolled 110 patients (65 males, age at diagnosis 67±71 months). Hypertrophic cardiomyopathy (HCM, N=48, 44%) was most frequent, followed by dilated cardiomyopathy (DCM, N=35 32%) and left ventricular non-compaction phenotype (LVNC, N=12, 11%). Mixed phenotype (N=7, 6%) and restrictive cardiomyopathy (RCM, N=3, 3%) were less common. No cases of arrhythmogenic right ventricular cardiomyopathy (ARVC) were detected. Five genotype-positive patients presented with negative clinical phenotype. A diagnosis was confirmed in all patients; the most common was sarcomere disease (30%, N=33) followed by metabolic (28%,N=31) disease, genetic syndromes (11%, N=12), neuromuscular (7,3%, N=8) diseases, and post-myocarditis cases (4,5%,N=5). Twenty-one patients (19%) were identified as idiopathic. At referral, 4,5% of children presented with NYHA class III/IV.

At 35 [14–72] months, 4 (3.7%) patients required ICD implantation, 8 (7.4%) underwent cardiac surgery, and 1 (1%) underwent heart transplant. Furthermore, 28 (26%) patients required hospitalization due to acute HF, with DCM patients being at higher risk (p&lt;0.01), 7 (6.8%) experienced arrhythmic events and 4 (3.9%) had syncope. Overall, 13 (12%) died (7 with metabolic disorders, 3 with genetic syndromes, 1 with a sarcomeric mutation, 1 post myocarditis, and 1 idiopathic).

Conclusions

In our cohort, HCM was the most common cause of pediatric CMP followed by DCM and non-compaction. MACE were present in 41% of patients. While HCM had a less severe phenotype (characterized by a higher arrhythmic burden), DCM was characterized by a higher prevalence of HF hospitalizations. DCM, inborn errors in metabolism and genetic syndromes had the worst outcome in terms mortality and heart failure long term.

Widespread availability of genetic testing provides several benefits to the clinician, confirming diagnosis in ambiguous cases and defining etiology in order to guide management and identifying relatives at risk.

Figure 1

Funding Acknowledgement

Type of funding source: None

Sex-related differences in exercise performance and outcome of patients with hypertrophic cardiomyopathy

AIMS

Exercise performance is known to predict outcome in hypertrophic cardiomyopathy (HCM), but whether sex-related differences exist is unresolved. We explored whether functional impairment, assessed by exercise echocardiography, has comparable predictive accuracy in females and males with HCM.

METHODS

We retrospectively evaluated 292 HCM patients (46 ± 16 years, 72% males), consecutively referred for exercise echocardiography; 242 were followed for 5.9 ± 4.2 years.

RESULTS

Peak exercise capacity was 6.5 ± 1.6 metabolic equivalents (METs). Sixty patients (21%) showed impaired exercise capacity (≤5 METs). Exercise performance was reduced in females, compared with males (5.6 ± 1.6 vs 6.9 ± 1.5 METs, p < 0.001; peak METs ≤ 5 in 40% vs 13%, p < 0.001), largely driven by a worse performance in women >50 years of age. At multivariable analysis, female sex was independently associated with impaired exercise capacity (odds ratio: 4.67; 95% confidence interval (CI): 1.83-11.90; p = 0.001). During follow-up, 24 patients (10%) met the primary endpoint (a combination of cardiac death, heart failure requiring hospitalization, sustained ventricular tachycardia, appropriate implantable cardioverter defibrillator discharge, resuscitated sudden cardiac death and cardioembolic stroke). Event-free survival was reduced in females (p = 0.035 vs males). Peak METs were inversely related to outcome in males (hazard ratio (HR) per unit increase: 0.57; 95% CI: 0.39-0.84; p = 0.004) but not in females (HR: 1.22; 95% CI: 0.66-2.24; p = 0.53).

CONCLUSIONS

Female patients with HCM showed significant age-related impairment in functional capacity compared with males, particularly evident in post-menopausal age groups. While women were at greater risk of HCM-related complications and death, impaired exercise capacity predicted adverse outcome only in men. These findings suggest the need for sex-specific management strategies in HCM.

P1243Comparison of long-term clinical course and outcome of MYBPC3 - versus MYH7 - related hypertrophic cardiomyopathy

Introduction

The presence of sarcomere mutations is a powerful predictor of heart failure-related outcomes in Hypertrophic Cardiomyopathy (HCM). However, whether the prevalence of left ventricular (LV) dysfunction differs in patients with mutations in the two most prevalent HCM-associated genes (i.e. MYBPC3 and MYH7) is unclear.

Purpose

To ascertain lifetime trends in prevalence of LV dysfunction in HCM associated with pathogenic or likely-pathogenic MYBPC3 versus MYH7 mutations.

Methods

Clinical and instrumental records of 402 HCM patients with MYBPC3 (N=251) or MYH7 (N=151) mutations were retrospectively reviewed. Presence of systolic dysfunction (ejection fraction [EF] <50%) and diastolic dysfunction (Grade II and III) were assessed for each patient. In vitro analysis of septal myectomy samples was performed to further compare electro-mechanic properties of MYBC3 and MYH7 patients.

Results

Patients were diagnosed at a mean age of 39±17 years and 63% were men. At first evaluation MYBPC3-HCM patients were less frequently obstructive (15% vs 26% in MYH7; p=0.005) and had lower LVEF (61±11% vs 64±9%; p=0.01). Prevalence of diastolic dysfunction increased with age and was lowest in MYBPC3 patients <40 years at diagnosis (19.5% vs 35.4% in MYH7, p=0.043). At a mean follow-up (FU) of 13±11 years, patients developed comparable left atrium enlargement (MYBPC3 52±29 ml/m2 vs 41±18 at baseline, p<0.001; MYH7 54±25ml/m2 vs 45±22, p=0.003). Prevalence of diastolic dysfunction was also similar. MYBPC3 patients had lower LVEF at final evaluation (61±11% vs 64±9% in MYH7, p=0.01) with greater prevalence of overt systolic dysfunction (EF<50%, MYBPC3 vs MYH7: 15% vs 5%, OR: 2.3 95% CI: 1.2–5.8, p=0.013).

No significant differences were observed in terms of NYHA class change, atrial fibrillation, stroke, heart failure, appropriate ICD intervention or cardiovascular death. However, prevalence of NSVT was higher for MYBPC3 (39% vs 14% in MYH7, p<0.0001). At Cox multivariable analysis independent predictors of systolic dysfunction at follow-up were MYBPC3 positive status (HR 2.53 95% CI: 1.09–5.82, p=0.029) and age at initial evaluation (HR 1.03 95% CI 1.00–1.06, p=0.027).

In vitro cross-sectional evaluation of myocardial samples taken during septal myectomy at different ages showed a decline in contraction-relaxation properties after age 40 in MYPBC3 carriers, but preserved function in MYH7 patients (Figure).

Kinetic of myosin cross-bridges

Conclusions

In HCM patients, mutations in the MYBPC3 gene and early diagnosis are associated with slowly progressing systolic impairment leading to overt dysfunction in 15% compared to 5% in MYH7-HCM. However, outcome was similar in the two subsets. These differences in lifetime myocardial performance between the two most common HCM-associated genes suggest diverse pathways of disease progression, potentially amenable to requiring different molecular approaches.

Long-term Outcomes of Pediatric-Onset Hypertrophic Cardiomyopathy and Age-Specific Risk Factors for Lethal Arrhythmic Events

Importance

Predictors of lethal arrhythmic events (LAEs) after a pediatric diagnosis of hypertrophic cardiomyopathy (HCM) are unresolved. Existing algorithms for risk stratification are limited to patients older than 16 years because of a lack of data on younger individuals.

Objective

To describe the long-term outcome of pediatric-onset HCM and identify age-specific arrhythmic risk factors.

Design, Setting, and Participants

This study assessed patients with pediatric-onset hypertrophic cardiomyopathy diagnosed from 1974 to 2016 in 2 national referral centers for cardiomyopathies in Florence, Italy. Patients with metabolic and syndromic disease were excluded.

Exposures

Patients were assessed at 1-year intervals, or more often, if their clinical condition required.

Main Outcomes and Measures

Lethal arrhythmic events (LAEs) and death related to heart failure.

Results

Of 1644 patients with HCM, 100 (6.1%) were 1 to 16 years old at diagnosis (median [interquartile range], 12.2 [7.3-14.1] years). Of these, 63 (63.0%) were boys. Forty-two of the 100 patients (42.0%) were symptomatic (defined as an New York Heart Association classification higher than 1 or a Ross score greater than 2). The yield of sarcomere gene testing was 55 of 70 patients (79%). During a median of 9.2 years during which a mean of 1229 patients were treated per year, 24 of 100 patients (24.0%) experienced cardiac events (1.9% per year), including 19 LAEs and 5 heart failure-related events (3 deaths and 2 heart transplants). Lethal arrhythmic events occurred at a mean (SD) age of 23.1 (11.5) years. Two survivors of LAEs with symptoms of heart failure experienced recurrent cardiac arrest despite an implantable cardioverter defibrillator. Risk of LAE was associated with symptoms at onset (hazard ratio [HR], 8.2; 95% CI, 1.5-68.4; P = .02) and Troponin I or Troponin T gene mutations (HR, 4.1; 95% CI, 0.9-36.5; P = .06). Adult HCM risk predictors performed poorly in this population. Data analysis occurred from December 2016 to October 2017.

Conclusions and Relevance

Pediatric-onset HCM is rare and associated with adverse outcomes driven mainly by arrhythmic events. Risk extends well beyond adolescence, which calls for unchanged clinical surveillance into adulthood. In this study, predictors of adverse outcomes differ from those of adult populations with HCM. In secondary prevention, the implantable cardioverter defibrillator did not confer absolute protection in the presence of limiting symptoms of heart failure.

Timing of invasive septal reduction therapies and outcome of patients with obstructive hypertrophic cardiomyopathy

BACKGROUND

Whether early vs. delayed referral to septal reduction therapies (SRT, alcohol septal ablation or surgical myectomy) bears prognostic relevance in hypertrophic obstructive cardiomyopathy (HOCM) is unresolved. We analyzed the impact of SRT timing on the outcome of HOCM patients.

METHODS

We followed 126 patients for 5 ± 4 years after SRT (mean age 53 ± 15 years; 55 post-ASA and 71 post-SM). Based on time-to-treatment (TTT; from HOCM diagnosis to SRT), patients were divided into three groups: "<3" years, N = 50; "3-5" years, N = 25; ">5" years, N = 51.

RESULTS

Patients with TTT > 5 years were younger at diagnosis and more often had atrial fibrillation (AF). Left ventricular outflow tract (LVOT) gradients were comparable in the 3 TTT groups. Two patients died peri-operatively, all with TTT > 5. Long-term, 8 patients died (3 suddenly and 5 due to heart failure). Mortality increased progressively with TTT (2% vs. 4% vs. 12% for TTT "<3", "3-5", and ">5" years, p for trend = 0.039). Independent predictors of disease progression (new-onset AF, worsening to NYHA III/IV symptoms, re-intervention or death) were TTT ("3-5" vs. "<3" years: HR: 4.988, 95%CI: 1.394-17.843; ">5" vs. "<3" years: HR: 3.420, 95%CI: 1.258-9.293, overall p-value = 0.025), AF at baseline (HR: 1.896, 95%CI: 1.002-3.589, p = 0.036) and LVOT gradient (HR per mm Hg increase: 1.022, 95%CI: 1.007-1.024, p = 0.023).

CONCLUSIONS

Delay in SRT referral has significant impact on long-term outcome of patients with HOCM, particularly when >5 years from first detection of gradient, even when successful relief of symptoms and gradient is achieved. Earlier interventions are associated with lower complication rates and better prognosis, suggesting the importance of timely SRT to maximize treatment benefit and prevent late HOCM-related complications.