Left ventricular geometry, global function, and dyssynchrony in infants and children with pompe cardiomyopathy undergoing enzyme replacement therapy

Efficacy and safety of enzyme replacement therapy with alglucosidase alfa for the treatment of patients with infantile-onset Pompe disease: a systematic review and metanalysis

Introduction

Pompe disease (PD) is a glycogen disorder caused by the deficient activity of acid alpha-glucosidase (GAA). We sought to review the latest available evidence on the safety and efficacy of recombinant human GAA enzyme replacement therapy (ERT) for infantile-onset PD (IOPD).

Methods

We systematically searched the MEDLINE (via PubMed) and Embase databases for prospective clinical studies evaluating ERT for IOPD on pre-specified outcomes. Meta-analysis was also performed.

Results

Of 1,722 articles identified, 16 were included, evaluating 316 patients. Studies were heterogeneous and with very low certainty of evidence for most outcomes. A moderate/high risk of bias was present for most included articles. The following outcomes showed improvements associated with alglucosidase alfa, over natural history of PD/placebo, for a mean follow-up of 48.3 months: left ventricular (LV) mass {mean change 131.3 g/m2 [95% confidence interval (CI) 81.02, 181.59]}, time to start ventilation (TSV) [HR 0.21 (95% CI: 0.12, 0.36)], and survival [HR 0.10 (95% CI: 0.05, 0.19)]. There were no differences between the pre- and post-ERT period for myocardial function and psychomotor development. Adverse events (AEs) after ERT were mild in most cases.

Conclusion

Our data suggest that alglucosidase alfa potentially improves LV mass, TSV, and survival in IOPD patients, with no important safety issues.

Systematic Review Registration

PROSPERO identifier (CRD42019123700).

Effects of enzyme replacement therapy on cardiac function in classic infantile Pompe disease

OBJECTIVE

Patients with classic infantile Pompe disease are born with a hypertrophic cardiomyopathy, which resolves after treatment with Enzyme replacement therapy (ERT). We aimed to assess potential deterioration of cardiac function over time using myocardial deformation analysis.

METHODS

Twenty-seven patients treated with ERT were included. Cardiac function was assessed at regular time intervals (before and after start with ERT) using conventional echocardiography and myocardial deformation analysis. Separate linear mixed effect models were used to asses temporal changes within the first year and the long-term follow-up period. Echocardiograms of 103 healthy children served as controls.

RESULTS

A total of 192 echocardiograms were analyzed. Median follow-up was 9.9 years (IQR: 7.5-16.3). Mean LVMI before start of ERT was increased 292.3 g/m² (95% CI: 202.8-381.8, mean Z-score + 7.6) and normalized after 1 year of ERT 87.3 g/m² (CI: 67.5-107.1, mean Z-score + 0.8, p < 0.001). Mean shortening fraction was within normal limits before start of ERT, up to 22 years of follow-up. Cardiac function measured by RV/LV longitudinal, and circumferential strain was diminished before start of ERT, but normalized (<-16%) within 1 year after start of ERT, and all remained within normal limits during follow-up. Only LV circumferential strain gradually worsened in Pompe patients (+0.24%/year) during follow-up compared to controls. LV longitudinal strain was diminished in Pompe patients, but did not change significantly over time compared to controls.

CONCLUSION

Cardiac function, measured using myocardial deformation analysis, normalizes after start of ERT, and seems to remain stable over a median follow-up period of 9.9 years.

Beyond Sarcomeric Hypertrophic Cardiomyopathy: How to Diagnose and Manage Phenocopies

PURPOSE OF REVIEW

We describe the most common phenocopies of hypertrophic cardiomyopathy, their pathogenesis, and clinical presentation highlighting similarities and differences. We also suggest a step-by-step diagnostic work-up that can guide in differential diagnosis and management.

RECENT FINDINGS

In the last years, a wider application of genetic testing and the advances in cardiac imaging have significantly changed the diagnostic approach to HCM phenocopies. Different prognosis and management, with an increasing availability of disease-specific therapies, make differential diagnosis mandatory. The HCM phenotype can be the cardiac manifestation of different inherited and acquired disorders presenting different etiology, prognosis, and treatment. Differential diagnosis requires a cardiomyopathic mindset allowing to recognize red flags throughout the diagnostic work-up starting from clinical and family history and ending with advanced imaging and genetic testing. Different prognosis and management, with an increasing availability of disease-specific therapies make differential diagnosis mandatory.

Cardiac responses in paediatric Pompe disease in the ADVANCE patient cohort

Pompe disease results from lysosomal acid α-glucosidase deficiency, which leads to cardiomyopathy in all infantile-onset and occasional late-onset patients. Cardiac assessment is important for its diagnosis and management. This article presents unpublished cardiac findings, concomitant medications, and cardiac efficacy and safety outcomes from the ADVANCE study; trajectories of patients with abnormal left ventricular mass z score at enrolment; and post hoc analyses of on-treatment left ventricular mass and systolic blood pressure z scores by disease phenotype, GAA genotype, and "fraction of life" (defined as the fraction of life on pre-study 160 L production-scale alglucosidase alfa). ADVANCE evaluated 52 weeks' treatment with 4000 L production-scale alglucosidase alfa in ≥1-year-old United States of America patients with Pompe disease previously receiving 160 L production-scale alglucosidase alfa. M-mode echocardiography and 12-lead electrocardiography were performed at enrolment and Week 52. Sixty-seven patients had complete left ventricular mass z scores, decreasing at Week 52 (infantile-onset patients, change -0.8 ± 1.83; 95% confidence interval -1.3 to -0.2; all patients, change -0.5 ± 1.71; 95% confidence interval -1.0 to -0.1). Patients with "fraction of life" <0.79 had left ventricular mass z score decreasing (enrolment: +0.1 ± 3.0; Week 52: -1.1 ± 2.0); those with "fraction of life" ≥0.79 remained stable (enrolment: -0.9 ± 1.5; Week 52: -0.9 ± 1.4). Systolic blood pressure z scores were stable from enrolment to Week 52, and no cohort developed systemic hypertension. Eight patients had Wolff-Parkinson-White syndrome. Cardiac hypertrophy and dysrhythmia in ADVANCE patients at or before enrolment were typical of Pompe disease. Four-thousand L alglucosidase alfa therapy maintained fractional shortening, left ventricular posterior and septal end-diastolic thicknesses, and improved left ventricular mass z score.Trial registry: ClinicalTrials.gov Identifier: NCT01526785 https://clinicaltrials.gov/ct2/show/NCT01526785.Social Media Statement: Post hoc analyses of the ADVANCE study cohort of 113 children support ongoing cardiac monitoring and concomitant management of children with Pompe disease on long-term alglucosidase alfa to functionally improve cardiomyopathy and/or dysrhythmia.

How to diagnose heart failure with preserved ejection fraction: the HFA-PEFF diagnostic algorithm: a consensus recommendation from the Heart Failure Association (HFA) of the European Society of Cardiology (ESC)

Making a firm diagnosis of chronic heart failure with preserved ejection fraction (HFpEF) remains a challenge. We recommend a new stepwise diagnostic process, the 'HFA-PEFF diagnostic algorithm'. Step 1 (P=Pre-test assessment) is typically performed in the ambulatory setting and includes assessment for HF symptoms and signs, typical clinical demographics (obesity, hypertension, diabetes mellitus, elderly, atrial fibrillation), and diagnostic laboratory tests, electrocardiogram, and echocardiography. In the absence of overt non-cardiac causes of breathlessness, HFpEF can be suspected if there is a normal left ventricular ejection fraction, no significant heart valve disease or cardiac ischaemia, and at least one typical risk factor. Elevated natriuretic peptides support, but normal levels do not exclude a diagnosis of HFpEF. The second step (E: Echocardiography and Natriuretic Peptide Score) requires comprehensive echocardiography and is typically performed by a cardiologist. Measures include mitral annular early diastolic velocity (e'), left ventricular (LV) filling pressure estimated using E/e', left atrial volume index, LV mass index, LV relative wall thickness, tricuspid regurgitation velocity, LV global longitudinal systolic strain, and serum natriuretic peptide levels. Major (2 points) and Minor (1 point) criteria were defined from these measures. A score ≥5 points implies definite HFpEF; ≤1 point makes HFpEF unlikely. An intermediate score (2-4 points) implies diagnostic uncertainty, in which case Step 3 (F1: Functional testing) is recommended with echocardiographic or invasive haemodynamic exercise stress tests. Step 4 (F2: Final aetiology) is recommended to establish a possible specific cause of HFpEF or alternative explanations. Further research is needed for a better classification of HFpEF.

Advancements in AAV-mediated Gene Therapy for Pompe Disease

Pompe disease (glycogen storage disease type II) is caused by mutations in acid α-glucosidase (GAA) resulting in lysosomal pathology and impairment of the muscular and cardio-pulmonary systems. Enzyme replacement therapy (ERT), the only approved therapy for Pompe disease, improves muscle function by reducing glycogen accumulation but this approach entails several limitations including a short drug half-life and an antibody response that results in reduced efficacy. To address these limitations, new treatments such as gene therapy are under development to increase the intrinsic ability of the affected cells to produce GAA. Key components to gene therapy strategies include the choice of vector, promoter, and the route of administration. The efficacy of gene therapy depends on the ability of the vector to drive gene expression in the target tissue and also on the recipient's immune tolerance to the transgene protein. In this review, we discuss the preclinical and clinical studies that are paving the way for the development of a gene therapy strategy for patients with early and late onset Pompe disease as well as some of the challenges for advancing gene therapy.

How to diagnose heart failure with preserved ejection fraction: the HFA-PEFF diagnostic algorithm: a consensus recommendation from the Heart Failure Association (HFA) of the European Society of Cardiology (ESC)

Making a firm diagnosis of chronic heart failure with preserved ejection fraction (HFpEF) remains a challenge. We recommend a new stepwise diagnostic process, the 'HFA-PEFF diagnostic algorithm'. Step 1 (P=Pre-test assessment) is typically performed in the ambulatory setting and includes assessment for heart failure symptoms and signs, typical clinical demographics (obesity, hypertension, diabetes mellitus, elderly, atrial fibrillation), and diagnostic laboratory tests, electrocardiogram, and echocardiography. In the absence of overt non-cardiac causes of breathlessness, HFpEF can be suspected if there is a normal left ventricular (LV) ejection fraction, no significant heart valve disease or cardiac ischaemia, and at least one typical risk factor. Elevated natriuretic peptides support, but normal levels do not exclude a diagnosis of HFpEF. The second step (E: Echocardiography and Natriuretic Peptide Score) requires comprehensive echocardiography and is typically performed by a cardiologist. Measures include mitral annular early diastolic velocity (e'), LV filling pressure estimated using E/e', left atrial volume index, LV mass index, LV relative wall thickness, tricuspid regurgitation velocity, LV global longitudinal systolic strain, and serum natriuretic peptide levels. Major (2 points) and Minor (1 point) criteria were defined from these measures. A score ≥5 points implies definite HFpEF; ≤1 point makes HFpEF unlikely. An intermediate score (2-4 points) implies diagnostic uncertainty, in which case Step 3 (F₁ : Functional testing) is recommended with echocardiographic or invasive haemodynamic exercise stress tests. Step 4 (F₂ : Final aetiology) is recommended to establish a possible specific cause of HFpEF or alternative explanations. Further research is needed for a better classification of HFpEF.

Early higher dosage of alglucosidase alpha in classic Pompe disease

Background With conventional enzyme replacement therapy (ERT), the clinical prognosis of classic Pompe disease is often unsatisfactory. About half the patients treated with ERT at the recommended dosage (20 mg/kg every other week) require ventilatory support within the first years of life. The heterogeneous response to ERT has been related to different factors, including cross-reactive immunologic material (CRIM) status and age at ERT initiation. Early treatment with a standard dosage of ERT improves clinical outcome and avoids mechanical ventilation in CRIM-positive patients detected at newborn screening, not preventing persistent hyperCKemia and muscle weakness. Later treatment with higher dosages of ERT was shown to provide similar benefits in CRIM-positive patients. Here, we report the clinical and biochemical outcomes of six patients with classic Pompe disease treated with different dosages of alglucosidase alpha at different ages. Methods A standard dosage of ERT was employed in five patients, sharing a poor prognosis after transient clinical improvements, even in the case of early treatment (four died at 22.2±11.9 months and one survived but required tracheostomy and gastrostomy). Early higher dosage of alglucosidase alpha (40 mg/kg/week from 14 days) was administered to one CRIM-positive patient with fetal persistent bradycardia. Results Early higher dosage of alclucosidase alpha not only achieved normal neuromotor development but also the full correction of biochemical markers of muscle damage until 3 years of age, an unmet target with the standard dosage. Speech delay was not prevented by this approach. Conclusions We suggest that early treatment with a higher dosage of ERT may further improve clinical prognosis in classic Pompe disease.

Safety of Intradiaphragmatic Delivery of Adeno-Associated Virus-Mediated Alpha-Glucosidase (rAAV1-CMV-hGAA) Gene Therapy in Children Affected by Pompe Disease

A first-in-human trial of diaphragmatic gene therapy (AAV1-CMV-GAA) to treat respiratory and neural dysfunction in early-onset Pompe disease was conducted. The primary objective of this study was to assess the safety of rAAV1-CMV-hGAA vector delivered to the diaphragm muscle of Pompe disease subjects with ventilatory insufficiency. Safety was assessed by measurement of change in serum chemistries and hematology, urinalysis, and immune response to GAA and AAV, as well as change in level of health. The data demonstrate that the AAV treatment was safe and there were no adverse events related to the study agent. Adverse events related to the study procedure were observed in subjects with lower baseline neuromuscular function. All adverse events were resolved before the end of the study, except for one severe adverse event determined not to be related to either the study agent or the study procedure. In addition, an anti-capsid and anti-transgene antibody response was observed in all subjects who received rAAV1-CMV-hGAA, except for subjects who received concomitant immunomodulation to manage reaction to enzyme replacement therapy, as per their standard of care. This observation is significant for future gene therapy studies and serves to establish a clinically relevant approach to blocking immune responses to both the AAV capsid protein and transgene product.

Cardiac outcome in classic infantile Pompe disease after 13 years of treatment with recombinant human acid alpha-glucosidase

BACKGROUND

Cardiac failure is the main cause of death in untreated classic infantile Pompe disease, an inheritable metabolic myopathy characterized by progressive hypertrophic cardiomyopathy. Since the introduction of enzyme replacement therapy (ERT), survival has increased significantly due to reduced cardiac hypertrophy and improved cardiac function. However, little is known about ERT's long-term effects on the heart.

METHODS

Fourteen patients were included in this prospective study. Cardiac dimensions, function, conduction and rhythm disturbances were evaluated at baseline and at regular intervals thereafter.

RESULTS

Treatment duration ranged from 1.1 to 13.9 years (median 4.8 years). At baseline, all patients had increased left ventricular mass index (LVMI) (median LVMI 226 g/m², range 98 to 599 g/m², Z-score median 7, range 2.4-12.4). During the first four weeks, LVMI continued to increase in six patients. Normalization of LVMI was observed in 13 patients (median 30 weeks; range 3 to 660 weeks). After clinical deterioration, LVMI increased again slightly in one patient. At baseline, PR interval was shortened in all patients; it normalized in only three. A delta-wave pattern on ECG was seen in six patients and resulted in documented periods of supraventricular tachycardias (SVTs) in three patients, two of whom required medication and/or ablation. One patient had severe bradycardia (35 beats/min).

CONCLUSION

This study shows that ERT significantly reduced LVMI, and sustained this effect over a period of 13.9 years. The risk for rhythm disturbances remains. Regular cardiac evaluations should be continued, also after initially good response to ERT.

Enzyme replacement therapy for infantile-onset Pompe disease

BACKGROUND

Infantile-onset Pompe disease is a rare and progressive autosomal-recessive disorder caused by a deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA). Current treatment involves enzyme replacement therapy (with recombinant human alglucosidase alfa) and symptomatic therapies (e.g. to control secretions). Children who are cross-reactive immunological material (CRIM)-negative require immunomodulation prior to commencing enzyme replacement therapy.Enzyme replacement therapy was developed as the most promising therapeutic approach for Pompe disease; however, the evidence is lacking, especially regarding the optimal dose and dose frequency.

OBJECTIVES

To assess the effectiveness, safety and appropriate dose regimen of enzyme replacement therapy for treating infantile-onset Pompe disease.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Inborn Errors of Metabolism Trials Register, which is compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the Cochrane Central Register of Controlled Trials (CENTRAL), Embase (Ovid), PubMed and LILACS, and CBM, CNKI, VIP, and WANFANG for literature published in Chinese. In addition, we searched three online registers: WHO International Clinical Trials Registry Platform ClinicalTrials.gov, and www.genzymeclinicalresearch.com. We also searched the reference lists of relevant articles and reviews.Date of last search of the Group's Inborn Errors of Metabolism Trials Register: 24 November 2016.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials of enzyme replacement therapy in children with infantile-onset Pompe disease.

DATA COLLECTION AND ANALYSIS

Two authors independently selected relevant trials, assessed the risk of bias and extracted data. We contacted investigators to obtain important missing information.

MAIN RESULTS

We found no trials comparing the effectiveness and safety of enzyme replacement therapy to another intervention, no intervention or placebo.We found one trial (18 participants) that fulfilled the selection criteria, comparing different doses of alglucosidase alfa. The trial provided low-quality evidence (this was a small trial, there were no numerical results available by dose group, random sequence generation and allocation concealment were unclear, and there was a lack of blinding). The duration of alglucosidase alfa treatment ranged from 52 weeks (the length of the original study) to up to three years (including the extended phase of the trial), with a median duration of treatment being 2.3 years.The trial only reported that clinical responses including cardiac function and motor development, as well as the proportion of children that were free of invasive ventilation, were similar in the 20 mg/kg every two weeks and the 40 mg/kg every two weeks groups (low-quality evidence). Long-term alglucosidase alfa treatment markedly extended survival as well as ventilation-free survival and improved cardiomyopathy (low-quality evidence). In relation to the number of children experiencing one or more infusion-related events, there was no significant difference between dose groups, risk ratio 0.83 (95% confidence interval 0.40 to 1.76) (low-quality of evidence). However, of note, at 52 weeks, five children in the 20 mg/kg every two weeks dose group experienced a total of 41 mild or moderate (none severe) infusion-related events and the six children in the 40 mg/kg every two weeks dose group experienced a total of 123 infusion-related events. By the end of the extended phase of the trial, five children in the 20 mg/kg every two weeks dose group experienced a total of 47 infusion-related events and the six children in the 40 mg/kg every two weeks dose group experienced a total of 177 infusion-related events. The trial was supported by the Genzyme Corporation.

AUTHORS' CONCLUSIONS

The search found no trials comparing the effectiveness and safety of enzyme replacement therapy to another intervention, no intervention or placebo. One small randomized controlled trial provided no robust evidence for which dosing schedule of alglucosidase alfa was more effective to treat infantile-onset Pompe disease. It is not deemed ethical to proceed with new placebo-controlled trials, therefore a randomized controlled trial with a large sample size comparing different dosing schedules of enzyme replacement therapy is needed. The main clinical outcomes (i.e. cardiac function, invasive ventilation, survival, motor development, adverse events (e.g. the development of antibodies)) should be standardized when evaluated and reported.

Pompe Disease: Diagnosis and Management. Evidence-Based Guidelines from a Canadian Expert Panel

Pompe disease is a lysosomal storage disorder caused by a deficiency of the enzyme acid alpha-glucosidase. Patients have skeletal muscle and respiratory weakness with or without cardiomyopathy. The objective of our review was to systematically evaluate the quality of evidence from the literature to formulate evidence-based guidelines for the diagnosis and management of patients with Pompe disease. The literature review was conducted using published literature, clinical trials, cohort studies and systematic reviews. Cardinal treatment decisions produced seven management guidelines and were assigned a GRADE classification based on the quality of evidence in the published literature. In addition, six recommendations were made based on best clinical practices but with insufficient data to form a guideline. Studying outcomes in rare diseases is challenging due to the small number of patients, but this is in particular the reason why we believe that informed treatment decisions need to consider the quality of the evidence.

Long-term prognosis of patients with infantile-onset Pompe disease diagnosed by newborn screening and treated since birth

OBJECTIVE

To determine the benefit of newborn screening for the long-term prognosis of patients with classic infantile-onset Pompe disease (IOPD).

STUDY DESIGN

A cohort of patients with classic IOPD were diagnosed by newborn screening, treated with recombinant human acid α-glucosidase (rhGAA), and followed prospectively. Outcome measurements included survival, left ventricular mass, serum creatinine kinase, motor function, mental development, and systemic manifestations.

RESULTS

Ten patients who presented with left ventricular hypertrophy at diagnosis received rhGAA infusions starting at a median age of 16 days (6-34 days). All patients were cross-reactive immunologic material-positive. After a median treatment time of 63 months (range 28-90 months), all could walk independently, and none required mechanical ventilation. All patients had motor capability sufficient for participating in daily activities, but muscle weakness over the pelvic girdle appeared gradually after 2 years of age. Ptosis was present in one-half of the patients, and speech disorders were common. Anti-rhGAA antibody titers were low (median maximal titer value 1:1600, range: undetectable ∼ 1:12,800).

CONCLUSION

By studying patients treated since birth who have no significant anti-rhGAA antibody interference, this prospective study demonstrates that the efficacy of rhGAA therapy is high and consistent for the treatment of classic IOPD. This study also exposes limitations of rhGAA treatment. The etiology of the manifestations in these early-treated patients will require further study.

Structural and functional cardiac analyses using modern and sensitive myocardial techniques in adult Pompe disease

The purpose of this study was to analyze comprehensively the heart using modern and sensitive myocardial techniques in order to determine if structural or functional cardiac alterations are present in adult Pompe disease. Twelve patients with adult Pompe disease and a control group of 187 healthy subjects of similar age and gender were included. Structural and functional cardiac characteristics were analyzed by conventional and 2D speckle-tracking echocardiography. In addition, in a subgroup of adult Pompe patients, we analyzed the myocardial and musculoskeletal features by means of cardiac and whole-body muscle magnetic resonance imaging. Patients with Pompe disease had significant structural and functional musculoskeletal alterations such as atrophy with fatty replacement and weakness in trunk and extremities. In contrast, Pompe patients had similar structural and functional myocardial features to healthy subjects (LV strain -20.7 ± 1.9 vs. -21.3 ± 2.1%; RV strain -24.2 ± 5.3 vs. -24.8 ± 3.8%; LA strain 41.5 ± 10.3 vs. 44.8 ± 11.0%; P > 0.05; and no evidence of LV and RV hypertrophy or LA enlargement). In addition, there was no evidence of valvular cardiac alterations, electrocardiographic abnormalities, or myocardial fibrosis in Pompe patients. In the current study analyzing the heart with modern and sensitive myocardial techniques, we evidenced that functional and structural cardiac alterations are not present when Pompe disease begins in adulthood. Therefore, these findings suggest that adult Pompe disease should not be taken into consideration in the differential diagnostic of structural or functional cardiac disorders.

Resolution of severe cardiomyopathy in infantile Pompe disease

Infantile Pompe disease is a rare inborn error of metabolism characterized by severe hypertrophic cardiomyopathy and generalised hypotonia occurring in infancy. We present a case of an infant with severe hypertrophic cardiomyopathy that resolved after treatment with enzyme replacement therapy.

Pompe disease results in a Golgi-based glycosylation deficit in human induced pluripotent stem cell-derived cardiomyocytes

Infantile-onset Pompe disease is an autosomal recessive disorder caused by the complete loss of lysosomal glycogen-hydrolyzing enzyme acid α-glucosidase (GAA) activity, which results in lysosomal glycogen accumulation and prominent cardiac and skeletal muscle pathology. The mechanism by which loss of GAA activity causes cardiomyopathy is poorly understood. We reprogrammed fibroblasts from patients with infantile-onset Pompe disease to generate induced pluripotent stem (iPS) cells that were differentiated to cardiomyocytes (iPSC-CM). Pompe iPSC-CMs had undetectable GAA activity and pathognomonic glycogen-filled lysosomes. Nonetheless, Pompe and control iPSC-CMs exhibited comparable contractile properties in engineered cardiac tissue. Impaired autophagy has been implicated in Pompe skeletal muscle; however, control and Pompe iPSC-CMs had comparable clearance rates of LC3-II-detected autophagosomes. Unexpectedly, the lysosome-associated membrane proteins, LAMP1 and LAMP2, from Pompe iPSC-CMs demonstrated higher electrophoretic mobility compared with control iPSC-CMs. Brefeldin A induced disruption of the Golgi in control iPSC-CMs reproduced the higher mobility forms of the LAMPs, suggesting that Pompe iPSC-CMs produce LAMPs lacking appropriate glycosylation. Isoelectric focusing studies revealed that LAMP2 has a more alkaline pI in Pompe compared with control iPSC-CMs due largely to hyposialylation. MALDI-TOF-MS analysis of N-linked glycans demonstrated reduced diversity of multiantennary structures and the major presence of a trimannose complex glycan precursor in Pompe iPSC-CMs. These data suggest that Pompe cardiomyopathy has a glycan processing abnormality and thus shares features with hypertrophic cardiomyopathies observed in the congenital disorders of glycosylation.

Reference values of the mitral annular peak systolic velocity (Sm) in 690 healthy pediatric patients, calculation of Z-score values, and comparison to the mitral annular Plane systolic excursion (MAPSE)

BACKGROUND

The mitral annular peak systolic velocity (Sm) is an echocardiographic measurement using tissue Doppler imaging to assess longitudinal left ventricular (LV) systolic function in children and adults. We determined growth-related changes in Sm to establish reference values for the entire pediatric age group.

METHODS AND RESULTS

A prospective study was conducted in a group of 690 healthy pediatric patients (age: 1 day-18 years). We determined the effects of age, sex, and body surface area (BSA) on the Sm values. Regression analysis was used to estimate Sm from age, BSA, and sex. In addition, a correlation of normal Sm with normal age-matched values of the M-mode parameter mitral annular plane systolic excursion (MAPSE) was measured. The Sm ranged from a mean of 5.8 cm/sec (Z-score ±2: 3.6-8.0 cm/sec) in the newborn to 11.8 cm/sec (Z-score ±2: 8.5-15.1 cm/sec) in the 18-year-old adolescent. The Sm values showed a positive correlation with age and BSA with a nonlinear course. There was no significant difference in Sm values between females and males. A significant correlation was found between Sm and MAPSE values.

CONCLUSION

Z-scores of Sm values were calculated and percentile charts were established to serve as reference data in patients with congenital heart diseases.

Pompe disease: early diagnosis and early treatment make a difference

Pompe disease (glycogen storage disease type II or acid maltase deficiency) is a lysosomal disorder in which acid α-glucosidase (GAA) deficiencies lead to intralysosomal accumulation of glycogen in all tissues; most notably in skeletal muscles. Both the patient's age at the onset of Pompe disease symptoms and the rate of deterioration caused by the disease can vary considerably. In classical infant-onset Pompe disease (IOPD), symptoms start very early in life, and death occurs soon afterward if the disease remains untreated. In later-onset Pompe disease, symptoms are slower to appear, and patients often progress to wheelchair confinement and eventual respiratory failure. A diagnosis can be made by screening for GAA in dried blood samples, followed either by GAA assessment in lymphocytes or in fibroblasts or by the genetic analysis of mutations. Treatment by enzyme replacement therapy (ERT) with alglucosidase alfa was approved for human use in 2006. In classical IOPD, treatment significantly lengthens survival and improves motor development and cardiac function. The sooner ERT begins, the better are the results. Newborn screening aims to take advantage of different technologies for diagnosing and treating newborns early on and it yields better outcomes. However, newborns diagnosed early and other long-term survivors may encounter fresh problems, making up a new phenotype of IOPD patients. Further modifications of the treatment, such as a decrease in immune responses to ERT, a higher dosage, a better uptake formulation, and gene therapy delivered locally or systemically are being explored.

The effect of different circadian blood pressure rhythms on left ventricular systolic dyssynchrony in patients with newly diagnosed essential hypertension

OBJECTIVES

Left ventricular (LV) synchronous contraction is impaired in patients with hypertension (HT). The deleterious effects of HT on cardiovascular system are more evident in patients with nondipper HT than dippers. In this study, we aimed to investigate the effect of nondipping HT on LV systolic synchronicity compared with dippers and controls.

METHODS

One hundred patients with newly diagnosed essential HT and 50 normotensive subjects were enrolled in this study. The hypertensive patients were assigned 2 groups comprising 55 dippers and 45 nondippers. Each subject underwent a comprehensive transthoracic echocardiographic examination. The evaluation of systolic dyssynchrony was performed by tissue synchronization imaging, and the time to regional peak systolic tissue velocity (Ts) in LV was measured on the basis of 12 segmental models. The standard deviation (SD) of the 12 LV segments (Ts-SD-12) and maximal difference in Ts between any two of the 12 LV segments (Ts-12) were calculated.

RESULTS

Compared with the control group, the synchronicity indexes were significantly prolonged in the hypertensive patients. Furthermore, Ts-SD-12 and Ts-12 values were found to be significantly impaired in patients with nondipper HT, compared with dippers: Ts-SD-12 (38.1 ± 18.7 vs. 31.8 ± 15.4, P ≤ 0.001); Ts-12 (123.0 ± 50.6 vs. 98.4 ± 42.3, P ≤ 0.001). Stepwise multivariate logistic regression analysis revealed a significant negative association between LV dyssynchrony indices and percentage decline in BP level from day to night.

CONCLUSION

Synchronous systolic contraction of LV is found to be significantly impaired in patients with nondipping circadian pattern of HT compared with dippers and the controls.