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

A Comprehensive Update on Late-Onset Pompe Disease

Pompe disease (PD) is an autosomal recessive disorder caused by mutations in the GAA gene that lead to a deficiency in the acid alpha-glucosidase enzyme. Two clinical presentations are usually considered, named infantile-onset Pompe disease (IOPD) and late-onset Pompe disease (LOPD), which differ in age of onset, organ involvement, and severity of disease. Assessment of acid alpha-glucosidase activity on a dried blood spot is the first-line screening test, which needs to be confirmed by genetic analysis in case of suspected deficiency. LOPD is a multi-system disease, thus requiring a multidisciplinary approach for efficacious management. Enzyme replacement therapy (ERT), which was introduced over 15 years ago, changes the natural progression of the disease. However, it has limitations, including a reduction in efficacy over time and heterogeneous therapeutic responses among patients. Novel therapeutic approaches, such as gene therapy, are currently under study. We provide a comprehensive review of diagnostic advances in LOPD and a critical discussion about the advantages and limitations of current and future treatments.

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.

Rare Metabolic and Endocrine Diseases with Cardiovascular Involvement: Insights from Cardiovascular Magnetic Resonance - A Review

The identification of rare diseases with cardiovascular involvement poses significant diagnostic challenges due to the rarity of the diseases, but also due to the lack of knowledge and expertise. Most of them remain underrecognized and undiagnosed, leading to clinical mismanagement and affecting the patients' prognosis, as these diseases are per definition life-threatening or chronic debilitating. This article reviews the cardiovascular involvement of the most well-known rare metabolic and endocrine diseases and their diagnostic approach through the lens of cardiovascular magnetic resonance (CMR) imaging and its prognostic role, highlighting its fundamental value compared to other imaging modalities.

Myocardial Strain and Association With Clinical Outcomes in Danon Disease: A Model for Monitoring Progression of Genetic Cardiomyopathies

Background

Myocardial strain can identify subclinical left ventricular dysfunction in various cardiac diseases, but its association with clinical outcomes in genetic cardiomyopathies remains unknown. Herein, we assessed myocardial strain in patients with Danon disease (DD), a rare X‐linked autophagic disorder that causes severe cardiac manifestations.

Methods and Results

Echocardiographic images were reviewed and used to calculate myocardial strain from a retrospective, international registry of patients with DD. Regression analyses were performed to evaluate for an association of global longitudinal strain (GLS) and ejection fraction with the composite outcome (death, ventricular assist device, heart transplantation, and implantable cardioverter defibrillator for secondary prevention). A total of 22 patients with DD (male 14 [63.6%], median age 16.5 years) had sufficient echocardiograms for analysis. Absolute GLS was reduced with a mean of 12.2% with an apical‐sparing pattern observed. Univariable regression for GLS and composite outcome showed an odds ratio of 1.32 (95% CI, 1.02–1.71) with P=0.03. For receiver operating characteristic analysis, the areas under the curve for GLS and ejection fraction were 0.810 (P=0.02) and 0.605 (P=0.44), respectively. An absolute GLS cutoff of 10.0% yielded a true positive rate of 85.7% and false positive rate of 13.3%.

Conclusions

In this cohort of patients with DD, GLS may be a useful assessment of myocardial function and may predict clinical outcomes. This study highlights the potential use of myocardial strain phenotyping to monitor disease progression and potentially to predict clinical outcomes in DD and other genetic cardiomyopathies.

Rare Variants in Autophagy and Non-Autophagy Genes in Late-Onset Pompe Disease: Suggestions of Their Disease-Modifying Role in Two Italian Families

Pompe disease is an autosomal recessive disorder caused by a deficiency in the enzyme acid alpha-glucosidase. The late-onset form of Pompe disease (LOPD) is characterized by a slowly progressing proximal muscle weakness, often involving respiratory muscles. In LOPD, the levels of GAA enzyme activity and the severity of the clinical pictures may be highly variable among individuals, even in those who harbour the same combination of GAA mutations. The result is an unpredictable genotype–phenotype correlation. The purpose of this study was to identify the genetic factors responsible for the progression, severity and drug response in LOPD. We report here on a detailed clinical, morphological and genetic study, including a whole exome sequencing (WES) analysis of 11 adult LOPD siblings belonging to two Italian families carrying compound heterozygous GAA mutations. We disclosed a heterogeneous pattern of myopathic impairment, associated, among others, with cardiac defects, intracranial vessels abnormality, osteoporosis, vitamin D deficiency, obesity and adverse response to enzyme replacement therapy (ERT). We identified deleterious variants in the genes involved in autophagy, immunity and bone metabolism, which contributed to the severity of the clinical symptoms observed in the LOPD patients. This study emphasizes the multisystem nature of LOPD and highlights the polygenic nature of the complex phenotype disclosed in these patients.

Cardiovascular disease in non-classic Pompe disease: A systematic review

Pompe disease is a rare inherited metabolic and neuromuscular disorder, presenting as a spectrum, with the classic infantile form on one end and the more slowly progressive non-classic form on the other end. While being a hallmark in classic infantile Pompe disease, cardiac involvement in non-classic Pompe disease seems rare. Vascular abnormalities, such as aneurysms and arterial dolichoectasia, likely caused by glycogen accumulation in arterial walls, have been reported in non-classic Pompe patients. With this first systematic review on cardiovascular disease in non-classic Pompe disease, we aim to gain insight in the prevalence and etiology of cardiovascular disease in these patients. Forty-eight studies (eight case-control studies, 15 cohort studies and 25 case reports/series) were included. Fourteen studies reported cardiac findings, 25 studies described vascular findings, and nine studies reported both cardiac and vascular findings. Severe cardiac involvement in non-classic Pompe disease patients has rarely been reported, particularly in adult-onset patients carrying the common IVS1 mutation. There are indications that intracranial dolichoectasia and aneurysms are more prevalent in non-classic Pompe patients compared to the general population. To further investigate the prevalence of cardiovascular disease in non-classic Pompe patients, larger case-control studies that also study established cardiovascular risk factors should be conducted.

Left atrial strain as sensitive marker of left ventricular diastolic dysfunction in heart failure

Aims

The purpose of this retrospective analysis was to examine the association of left atrial (LA) strain (i.e. LA reservoir function) with left ventricular diastolic dysfunction (DD) in patients with heart failure with reduced and preserved left ventricular ejection fraction (LVEF).

Methods and results

We analysed the baseline echocardiographic recordings of 300 patients in sinus rhythm from the SOCRATES‐PRESERVED and SOCRATES‐REDUCED studies. LA volume index was normal in 89 (29.7%), of whom 60.6% had an abnormal LA reservoir strain (i.e. ≤23%). In addition, the extent of LA strain impairment was significantly associated with the severity of DD according to the 2016 American Society of Echocardiography recommendations (DD grade I: LA strain 22.2 ± 6.6, rate of abnormal LA strain 62.9%; DD grade II: LA strain 16.6 ± 7.4, rate of abnormal LA strain 88.6%; DD grade III: LA strain 11.1 ± 5.4%, rate of abnormal LA strain 95.7%; all P < 0.01). In line with these findings, LA strain had a good diagnostic performance to determine severe DD [area under the curve 0.83 (95% CI 0.77–0.88), cut‐off 14.1%, sensitivity 80%, specificity 77.8%], which was significantly better than for LA volume index, LA total emptying fraction, and the mitral E/e′ ratio.

Conclusions

The findings of this analysis suggest that LA strain could be a useful parameter in the evaluation of DD in patients with heart failure and sinus rhythm, irrespective of LVEF.

Potential Usefulness and Clinical Relevance of Adding Left Atrial Strain to Left Atrial Volume Index in the Detection of Left Ventricular Diastolic Dysfunction

OBJECTIVES

The purpose of this study was to analyze the potential usefulness and clinical relevance of adding left atrial (LA) strain to left atrial volume index (LAVI) in the detection of left ventricular diastolic dysfunction (LVDD) in patients with preserved left ventricular ejection fraction (LVEF).

BACKGROUND

Recent studies have suggested that LA strain could be of use in the evaluation of LVDD. However, the potential utility and clinical significance of adding LA strain to LAVI in the detection of LVDD remains uncertain.

METHODS

Using 2-dimensional speckle-tracking echocardiography, we analyzed a population of 517 patients in sinus rhythm at risk for LVDD such as those with arterial hypertension, diabetes mellitus, or history of coronary artery disease and preserved LVEF.

RESULTS

In patients with LV diastolic alterations and estimated elevated LV filling pressures, the rate of abnormal LA strain was significantly higher than an abnormal LAVI (62.4% vs. 33.6%, p < 0.01). In line with this, in patients with normal LAVI, high rates of LV diastolic alterations and abnormal LA strain were present (rates 80% and 29.4%, respectively). In agreement with these findings, adding LA strain to LAVI in the current evaluation of LVDD increased significantly the rate of detection of LVDD (relative and absolute increase 73.3% and 9.9%; rate of detection of LVDD: from 13.5% to 23.4%; p < 0.01). Regarding the clinical relevance of these findings, an abnormal LA strain (i.e., <23%) was significantly associated with worse New York Heart Association functional class, even when LAVI was normal. Moreover, in a retrospective post hoc analysis an abnormal LA strain had a significant association with the risk of heart failure hospitalization at 2 years (odds ratio: 6.6 [95% confidence interval: 2.6 to 16.6]) even adjusting this analysis for age and sex and in patients with normal LAVI.

CONCLUSIONS

The findings from this study provide important insights regarding the potential usefulness and clinical relevance of adding LA strain to LAVI in the detection of LVDD in patients with preserved LVEF.

Imaging of Left Ventricular Hypertrophy: a Practical Utility for Differential Diagnosis and Assessment of Disease Severity

PURPOSE OF REVIEW

Left ventricular hypertrophy (LVH) is often encountered in clinical practice, and it is a risk factor for cardiac mortality and morbidity. Determination of the etiology and disease severity is important for the management of patients with LVH. The aim of this review is to show the remarkable progress in cardiac imaging and its importance in clinical practice.

RECENT FINDINGS

This review focuses on clinical features and characteristic cardiac imaging in LVH caused by various diseases including hypertension, aortic valve stenosis, hypertrophic cardiomyopathy, and secondary cardiomyopathies. The usefulness of echocardiography as a tool of general versatility including hemodynamic evaluation and the usefulness of cardiac magnetic resonance imaging for assessment of cardiac morphology and myocardial tissue characteristics of relevance for LVH are described. Imaging modalities now have central roles in the differentiation and prognostic assessment of LVH.

Early detection of cardiac alterations by left atrial strain in patients with risk for cardiac abnormalities with preserved left ventricular systolic and diastolic function

This study sought to examine whether early cardiac alterations could be detected by left atrial (LA) strain in patients with risk for cardiac abnormalities. In this cross-sectional and retrospective study, we included patients with (n = 234) and without (n = 48) risk for cardiac abnormalities (i.e. those with arterial hypertension, diabetes mellitus and/or a history of coronary artery disease) of similar age and with preserved left ventricular (LV) systolic and diastolic function according to standard criteria. LA strain was significantly altered in patients with risk for cardiac abnormalities in comparison to those without risk (29.2 ± 8.6 vs. 38.5 ± 12.6%; rate of impaired LA strain: 18.8% vs. 0%; all p < 0.01) and was the most sensitive parameter to detect early LA alterations in comparison with other LA functional parameters (rate of impaired LA strain rate, LA total emptying fraction, and LA expansion index 3.8%, 7.3%, and 3.8%, respectively). Moreover, in patients with risk for cardiac abnormalities LA strain was altered even in the absence of subtle LV systolic and diastolic alterations (rates 13.9% and 6.8%), albeit to a lesser extent than in patients with an abnormal LV longitudinal systolic strain or abnormal mitral annular e' velocities (rates 48.5% and 24.4%). Regarding the clinical relevance of these findings, an impaired LA strain (i.e. < 23%) was significantly linked to exertional dyspnea (OR 3.5 [1.7-7.0]) even adjusting the analyses by age, gender and subtle LV abnormalities. In conclusion, the findings from this study suggest that LA strain measurements could be useful to detect early cardiac alterations in patients with risk for cardiac abnormalities with preserved LV systolic and diastolic function and that these early LA strain alterations could be linked to exertional dyspnea.

The emerging phenotype of late-onset Pompe disease: A systematic literature review

BACKGROUND

Pompe disease is an autosomal recessive disorder caused by deficiency of the lysosomal glycogen-hydrolyzing enzyme acid α-glucosidase (GAA). The adult-onset form, late-onset Pompe disease (LOPD), has been characterized by glycogen accumulation primarily in skeletal, cardiac, and smooth muscles, causing weakness of the proximal limb girdle and respiratory muscles. However, increased scientific study of LOPD continues to enhance understanding of an evolving phenotype.

PURPOSE

To expand our understanding of the evolving phenotype of LOPD since the approval of enzyme replacement therapy (ERT) with alglucosidase alfa (Myozyme™/Lumizyme™) in 2006.

METHODS

All articles were included in the review that provided data on the charactertistics of LOPD identified via the PubMed database published since the approval of ERT in 2006. All signs and symptoms of the disease that were reported in the literature were identified and included in the review.

RESULTS

We provide a comprehensive review of the evolving phenotype of LOPD. Our findings support and extend the knowledge of the multisystemic nature of the disease.

CONCLUSIONS

With the advent of ERT and the concurrent increase in the scientific study of LOPD, the condition once primarily conceptualized as a limb-girdle muscle disease with prominent respiratory involvement is increasingly recognized to be a condition that results in signs and symptoms across body systems and structures.

Pattern and prognostic value of cardiac involvement in patients with late-onset pompe disease: a comprehensive cardiovascular magnetic resonance approach

BACKGROUND

Pompe disease is an autosomal recessive disorder caused by deficiency of the lysosomal α-1,4-glucosidase leading to accumulation of glycogen in target tissues with progressive organ failure. While the early infantile-onset form is characterized by early severe hypertrophic cardiomyopathy with cardiac and respiratory failure, clinically relevant cardiomyopathy seems to be uncommon in patients with late-onset Pompe disease, and the prevalence and nature of myocardial abnormalities are still to be clarified.

METHODS

Seventeen patients with genetically proven late-onset Pompe disease (50 ± 18 years, 11 male) and 18 age- and gender-matched healthy controls (44 ± 10 year, 12 male) underwent comprehensive cardiovascular magnetic resonance (CMR) including conventional and advanced techniques: cine and feature tracking-based strain imaging for depiction of (even subtle) systolic LV dysfunction as well as late gadolinium enhancement (LGE) and myocardial extracellular volume fraction (ECV) quantification for focal and diffuse fibrosis detection.

RESULTS

All patients had normal left ventricular (LV) and right ventricular (RV) volumes and normal LV and RV ejection fraction. In comparison to healthy controls, neither conventional cine nor advanced feature-tracking based-strain imaging could depict any (subclinical) myocardial systolic dysfunction. Three (18%) of the patients had non-ischemic LGE in the basal inferolateral wall and 21% demonstrated elevated global ECV values suggestive of interstitial myocardial fibrosis. Non-specific abnormalities such as left atrial (LA) dilatation were present in two patients, while LV hypertrophy was seen only in one. Two of the three LGE-positive patients were also hypertensive and demonstrated high global ECV values (>30%) in addition to dilated LA. After a median follow-up of 25 (11-29) months, only one cardiovascular event occurred: one of the LGE-positive patients with a high cardiovascular risk profile suffered an acute coronary syndrome.

CONCLUSION

In contrast to the early infantile-onset form of Pompe disease, mild and rather non-specific cardiac abnormalities can be detected by CMR only in a small proportion of patients with late-onset Pompe disease. The observed structural abnormalities seem to result from an interplay between the storage disease and other comorbidities and they did not affect short-term to mid-term prognosis in adult Pompe patients.

Severe Cardiomyopathy as the Isolated Presenting Feature in an Adult with Late-Onset Pompe Disease: A Case Report

Many inborn errors of metabolism can cause cardiomyopathy. Cardiomyopathy associated with glycogen storage includes PRKAG2-associated glycogen storage disease (GSD), Danon disease, infantile-onset Pompe disease (GSD II), GSD III, GSD IV, and phosphofructokinase deficiency (Tarui disease or GSD VII).We present a 35-year-old female who presented with cardiomyopathy after a pregnancy complicated by primary hyperparathyroidism. She had enjoyed excellent health until her first pregnancy at age 33. One week postpartum, she developed dyspnea and an echocardiogram revealed left ventricular ejection fraction (LVEF) of 35%. A cardiac MRI was consistent with nonischemic cardiomyopathy with an infiltrative process. Endomyocardial biopsy showed striking sarcoplasmic vacuolization, excess glycogen by PAS staining, and frequent membrane-bound glycogen by electron microscopy, consistent with lysosomal GSD. Acid alpha-glucosidase (GAA) activity in skin fibroblasts was in the affected range for Pompe disease. Sequencing of the GAA gene revealed a paternally inherited pathogenic c.525delT (p.Glu176Argfs*45) and a de novo c.309C>G (p.Cys103Trp) with unknown pathogenicity. Testing of the familial mutations in her daughter indicated that the variants in the proband were in trans. 26-gene cardiomyopathy sequencing panel had normal results thereby excluding GSD III, Danon disease, Fabry disease, and PRKAG2-associated cardiomyopathy. Therefore, results strongly suggest a diagnosis of Pompe disease.Pompe disease has a broad disease spectrum, including infantile-onset (IOPD) and late-onset (LOPD) forms. LOPD typically presents with proximal muscle weakness and respiratory insufficiency in childhood or late adulthood. Our case may represent a very unusual presentation of adult LOPD with isolated cardiomyopathy without skeletal muscle involvement or respiratory failure.

Elevated Plasma Cardiac Troponin T Levels Caused by Skeletal Muscle Damage in Pompe Disease

Background—

Elevated plasma cardiac troponin T (cTnT) levels in patients with neuromuscular disorders may erroneously lead to the diagnosis of acute myocardial infarction or myocardial injury.

Methods and Results—

In 122 patients with Pompe disease, the relationship between cTnT, cardiac troponin I, creatine kinase (CK), CK-myocardial band levels, and skeletal muscle damage was assessed. ECG and echocardiography were used to evaluate possible cardiac disease. Patients were divided into classic infantile, childhood-onset, and adult-onset patients. cTnT levels were elevated in 82% of patients (median 27 ng/L, normal values <14 ng/L). Cardiac troponin I levels were normal in all patients, whereas CK-myocardial band levels were increased in 59% of patients. cTnT levels correlated with CK levels in all 3 subgroups ( P <0.001). None of the abnormal ECGs recorded in 21 patients were indicative of acute myocardial infarction, and there were no differences in cTnT levels between patients with and without (n=90) abnormalities on ECG (median 28 ng/L in both groups). The median left ventricular mass index measured with echocardiography was normal in all the 3 subgroups. cTnT mRNA expression in skeletal muscle was not detectable in controls but was strongly induced in patients with Pompe disease. cTnT protein was identified by mass spectrometry in patient-derived skeletal muscle tissue.

Conclusions—

Elevated plasma cTnT levels in patients with Pompe disease are associated with skeletal muscle damage, rather than acute myocardial injury. Increased cTnT levels in Pompe disease and likely other neuromuscular disorders should be interpreted with caution to avoid unnecessary cardiac interventions.