Fabry disease in patients with hypertrophic cardiomyopathy (HCM)

Fabry disease is an X-linked recessive lysosomal storage disorder with variable phenotype characterized by the accumulation of glycosphingolipid in various tissues. Unlike patients with the classical systemic Fabry disease entity, who present with multiple organ involvement, patients with a cardiac variant of Fabry disease are characterized mainly by myocardial hypertrophy. Therefore, the cardiac variant of Fabry disease may be defined as a cardiomyocytic storage disorder, thus, mimicking the clinical features of hypertrophic obstructive and especially non-obstructive cardiomyopathy. In patients with unexplained left ventricular hypertrophy the diagnosis of a cardiac variant of Fabry disease is performed by light- and electron microscopic evaluation of endomyocardial catheter biopsy specimens and/or serologic investigations (decreased activity of alpha-galactosidase A in plasma or leucocytes). Several studies show that between 4% and 8% of unselected patients with the clinical features of hypertrophic non-obstructive cardiomyopathy have a cardiac variant of Fabry disease. In each patient with unexplained myocardial hypertrophy concealed myocardial storage disease, especially cardiac Fabry disease has to be considered and should be ruled out or confirmed by endomyocardial catheter biopsy. This is important because of the recently reported alpha-galactosidase A enzyme replacement therapy in Fabry disease. Randomized, multicenter studies are mandatory to test the hypothesis that enzyme replacement therapy leads to a beneficial clinical effect in the cardiac variant form of Fabry disease and may prevent the progression of the disease in asymptomatic patients.     

Cardiac Involvement in Fabry Disease: JACC Review Topic of the Week

Fabry disease (FD) is a rare X-linked inherited lysosomal storage disorder caused by deficient α-galactosidase A activity that leads to an accumulation of globotriasylceramide (Gb3) in affected tissues, including the heart. Cardiovascular involvement usually manifests as left ventricular hypertrophy, myocardial fibrosis, heart failure, and arrhythmias, which limit quality of life and represent the most common causes of death. Following the introduction of enzyme replacement therapy, early diagnosis and treatment have become essential to slow disease progression and prevent major cardiac complications. Recent advances in the understanding of FD pathophysiology suggest that in addition to Gb3 accumulation, other mechanisms contribute to the development of Fabry cardiomyopathy. Progress in imaging techniques have improved diagnosis and staging of FD-related cardiac disease, suggesting a central role for myocardial inflammation and setting the stage for further research. In addition, with the recent approval of oral chaperone therapy and new treatment developments, the FD-specific treatment landscape is rapidly evolving.     

Detection of preclinical left ventricular dysfunction in Fabry disease: the contribution of tissue Doppler.

INTRODUCTION: Fabry disease is a rare X-linked lysosomal storage disorder caused by a deficiency of alpha-galactosidase, which results in progressive intracellular accumulation of glycosphingolipids in various tissues. Cardiac involvement is frequent, with left ventricular (LV) hypertrophy (concentric, apical or asymmetric septal) as the most common finding. Evaluating LV systolic dysfunction with conventional echocardiography is not sufficiently sensitive to detect impaired myocardial function early in the course of the disease. Doppler myocardial imaging can quantify changes in global and regional longitudinal myocardial function with great precision. AIM: To identify parameters of cardiac dysfunction in patients with Fabry disease with no cardiac symptoms using conventional or Doppler echocardiography and tissue Doppler (including tissue tracking, strain and strain rate). METHODS: Four patients with Fabry disease (3 female; mean age 47 +/- 17 years) and 29 healthy controls (19 female and 10 male; mean age 38 +/- 14 years) were studied with conventional echocardiography and tissue Doppler imaging using a Vivid 7 scanner. The following parameters were measured: LV dimensions, ejection fraction (using Simpson's rule), systolic and diastolic velocities and tissue tracking of the mitral annulus at six sites (apical views). LV peak systolic strain and strain rate were obtained in 12 segments from apical views. RESULTS: Two patients had LV hypertrophy (one concentric and one apical). Diastolic impairment was detected in three patients by reduced flow propagation velocity of early transmitral flow (Vp) and E/Vp ratio. Mitral annulus systolic velocities were lower in Fabry disease than in the controls. Peak systolic strain and strain rate were diminished in all segments in three patients, showing impaired myocardial systolic function. The results are presented for each of the four patients. CONCLUSIONS: In patients with Fabry disease, with no cardiac symptoms and normal LV systolic function on conventional echocardiography, diastolic dysfunction was detected by Vp and E/Vp ratio regardless of LV hypertrophy. However, tissue Doppler imaging was able to detect impaired myocardial systolic function, particularly in patients with LV hypertrophy.     

Fabry disease,an under-recognized multisystemic disorder: expert recommendations for diagnosis,management, and enzyme replacement therapy

Fabry disease (alpha-galactosidase A deficiency) is an X-linked recessive lysosomal storage disorder. Although the disease presents in childhood and culminates in cardiac, cerebrovascular, and end-stage renal disease, diagnosis is often delayed or missed. This paper reviews the key signs and symptoms of Fabry disease and provides expert recommendations for diagnosis, follow-up, medical management, and the use of enzyme replacement therapy. Recommendations are based on reviews of the literature on Fabry disease, results of recent clinical trials, and expertise of the authors, all of whom have extensive clinical experience with Fabry disease and lysosomal storage disorders and represent subspecialties involved in treatment. All males and female carriers affected with Fabry disease should be followed closely, regardless of symptoms or treatment status. Clinical trials have shown that recombinant human alpha-galactosidase A replacement therapy--the only disease-specific therapy currently available for Fabry disease--is safe and can reverse substrate storage in the lysosome, the pathophysiologic basis of the disease. Enzyme replacement therapy in all males with Fabry disease (including those with end-stage renal disease) and female carriers with substantial disease manifestations should be initiated as early as possible. Additional experience is needed before more specific recommendations can be made on optimal dosing regimens for reversal; maintenance; and prevention of disease manifestations in affected males, symptomatic carrier females, children, and patients with compromised renal function.     

Fabry disease: focus on cardiac manifestations and molecular mechanisms

PATHOGENESIS: Fabry disease is an inherited lysosomal storage disorder caused by deficiency of the enzyme alpha-galactosidase A. The enzyme deficiency results in accumulation of glycosphingolipids in the lysosomes n nearly all cell types and tissues leading to a multisystem disease. MANIFESTATIONS include painful crisis, angiokeratomas, corneal dystrophy, and hypohydrosis. The severe renal, cerebrovascular, and cardiac involvement is predominantly responsible for premature mortality in Fabry patients. The disease is X-linked and manifests primarily in hemizygous males but also heterozygous females can be affected. CARDIAC INVOLVEMENT is frequent in Fabry disease. Patients develop hypertrophic cardiomyopathy, arrhythmias, conduction abnormalities, and valvular abnormalities. Although Fabry disease leads to a complex clinical syndrome, there are studies indicating that manifestations can be limited to the heart. The isolated cardiac variant of Fabry disease seems to be more common than previously thought: around 3-6% of male patients with left ventricular hypertrophy seem to suffer from this disease variant. ENZYME REPLACEMENT THERAPY: Recent advances in molecular biology and genetic engineering have enabled the development of enzyme replacement therapy in Fabry disease. Results from two independent therapy studies are indeed promising: Infusion of the enzyme preparation seems to be well tolerated and effective in catabolizing the lipid deposits. This enzyme replacement therapy could be one of the first examples for causal treatment of left ventricular hypertrophy. Therefore, early diagnosis of hypertrophy patients with the cardiac variant of Fabry disease is important.     

Histopathological evidence of Fabry disease in a female patient with left ventricular noncompaction

Fabry disease is a rare X-linked lysosomal storage disorder caused by mutations in the alpha-galactosidase gene. The most frequent cardiac presentation of Fabry disease is cardiomyopathy characterized by left ventricular (LV) hypertrophy, usually concentric.Heart disease in affected females tends to be clinically recognized later than in males and cardiac complications are the most frequently reported cause of death in females with Fabry disease. There are few data regarding the association between Fabry disease and LV noncompaction. We report a case of a 30-year-old asymptomatic woman, heterozygous for a nonsense alpha-galactosidase gene mutation (p.R220X), who presented LV noncompaction on cardiac magnetic resonance imaging, without LV wall hypertrophy. Histopathological examination of myocardial fragments showed marked deposition of glycosphingolipids in cardiomyocytes, confirming the diagnosis of Fabry cardiomyopathy. Based on this finding, the patient was proposed for enzyme replacement therapy. This case illustrates the role of endomyocardial biopsy in the clarification of doubtful or atypical findings related to cardiac Fabry disease, even in heterozygous women, and corroborates the contention that Fabry disease should be included in the differential diagnosis of LV hypertrabeculation/noncompaction.     

Morbus Fabry of the heart Why should cardiologists care?

Fabry Disease is an X-linked lysosomal storage disorder leading to the accumulation of glycosphingolipids, mainly globotriaosylceramides in all tissues and solid organs of the body. The disease was described by Johannes Fabry and William Anderson coevally in 1898. Beside the involvement of the central nervous system, peripheral nerves, kidneys, skin and endovascular endothelium, the heart plays a major role in the disease. Left ventricular hypertrophy is one hallmark initially presenting with preserved ventricular function. However, with progression of the disease patients die due to heart failure. Though angina is often reported, the incidence of epicardial coronary stenosis is not a dominant feature, if at all small vessel disease can occur. In respect of arrhythmias a broad spectrum can be seen including shortened or prolonged PR-intervals, AV blocks of different degrees and sometimes malignant ventricular arrhythmias. In the past, women were considered to be carriers of the disease but hardly to develop clinical symptoms. In recent years there is evidence that female carriers may more often be affected with severe symptoms. In addition, a group of Fabry patients displaying mainly cardiac involvement were described as having a cardiac variant of the disease. This implied the hypothesis that some of those patients with unexplained myocardial hypertrophy do suffer from Fabry disease. Since 2002 enzyme replacement therapy is available and there is first evidence for its efficacy to reduce hypertrophy and increase myocardial function. If this is associated with a prognostic improvement has to be determined in future studies.     

Impact of enzyme replacement therapy on cardiac morphology and function and late enhancement in Fabry's cardiomyopathy

The present study evaluated the evolution of cardiac morphology, function, and late enhancement as a noninvasive marker of myocardial fibrosis, and their inter-relation during enzyme replacement therapy in patients with Fabry's disease using magnetic resonance imaging and color Doppler myocardial imaging. Late enhancement, which was present in up to 50% of patients, was associated with increased left ventricular mass, the failure of a significant regression of hypertrophy during enzyme replacement therapy, and worse segmental myocardial function. Late enhancement may predict the effect of enzyme replacement therapy on left ventricular mass and cardiac function.     

Morbus Fabry of the heart. Why should cardiologists care?

Summary Fabry Disease is an X-linked lysosomal storage disorder leading to the accumulation of glycosphingolipids, mainly globotriaosylceramides in all tissues and solid organs of the body. The disease was described by Johannes Fabry and William Anderson coevally in 1898. Beside the involvement of the central nervous system, peripheral nerves, kidneys, skin and endovascular endothelium, the heart plays a major role in the disease. Left ventricular hypertrophy is one hallmark initially presenting with preserved ventricular function. However, with progression of the disease patients die due to heart failure. Though angina is often reported, the incidence of epicardial coronary stenosis is not a dominant feature, if at all small vessel disease can occur. In respect of arrhythmias a broad spectrum can be seen including shortened or prolonged PR-intervals, AV blocks of different degrees and sometimes malignant ventricular arrhythmias. In the past, women were considered to be carriers of the disease but hardly to develop clinical symptoms. In recent years there is evidence that female carriers may more often be affected with severe symptoms. In addition, a group of Fabry patients displaying mainly cardiac involvement were described as having a cardiac variant of the disease. This implied the hypothesis that some of those patients with unexplained myocardial hypertrophy do suffer from Fabry disease. Since 2002 enzyme replacement therapy is available and there is first evidence for its efficacy to reduce hypertrophy and increase myocardial function. If this is associated with a prognostic improvement has to be determined in future studies.     

Clinical usefulness of tissue Doppler imaging in predicting preclinical Fabry cardiomyopathy

Fabry cardiomyopathy (FC) is characterized by left ventricular hypertrophy (LVH). The aim of this study is to determine whether early changes revealed by tissue Doppler imaging (TDI) are useful for detecting preclinical cardiac abnormalities in patients with this X-linked genetic disorder. If so, this tool could help in deciding whether to begin enzymatic therapy earlier than otherwise. METHODS AND RESULTS: 59 consecutive patients with confirmed Fabry disease (FD) underwent conventional and TD echocardiography. FD patients with and without LVH had significantly lower early diastolic tissue Doppler velocities (Ea) compared with the control group (P<0.001); The isovolumic relaxation time (IVRT) was significantly longer in the FD group with LVH (P<0.001). Isovolumic contraction time (IVCT) was significantly shorter in the FD group without LVH compared with the control group (P<0.001). Additionally, peak systolic wall motion velocity (Sa) was significantly lower in patients with LVH, compared with those without LVH (P<0.001). The systolic myocardial velocity correlates inversely with septum and posterior wall thickness (r: -0.74 and r: -0.90; P<0.001 respectively). In respect of predicting preclinical cardiac impairment, the area under the ROC curve of 0.83 suggests an optimal IVRT cut-off point of 60 ms for separating early cardiac impairment from the established condition. This gives a 96.6% specificity rate for the early detection of cardiac involvement. The best parameter for detecting preclinical FC is the IVCT, with a cut-off point of 105 ms, which shows high sensitivity and specificity (100% and 91%, respectively; AUC: 0.97). CONCLUSIONS: Myocardial contraction and relaxation evaluation confirms that TDI is a reliable method for early identification of preclinical FC, even before FC patients develop LVH.     

Tissue Doppler imaging for evaluation of myocardial function in patients with diabetes mellitus

PURPOSE OF REVIEW: Heart failure and diabetes mellitus are frequently associated, and diabetes appears to potentiate the clinical presentation of heart failure related to other causes. The purpose of this review is to examine recent advances in the application of tissue Doppler imaging for the assessment of diabetic heart disease. RECENT FINDINGS: Recent studies have documented that both myocardial systolic and diastolic abnormalities can be identified in apparently healthy patients with diabetes and no overt cardiac dysfunction. Interestingly, these are disturbances of longitudinal function, with compensatory increases of radial function-suggesting primary involvement of the subendocardium, which is a hallmark of myocardial ischemia. Despite this, there is limited evidence that diabetic microangiopathy is responsible-with reduced myocardial blood volume rather than reduced resting flow, and at least some evidence suggesting a normal increment of tissue velocity with stress. Finally, a few correlative studies have shown association of diabetic myocardial disease with poor glycemic control, while angiotensin converting enzyme inhibition may be protective. SUMMARY: Tissue Doppler imaging (and the related technique of strain rate imaging) appears to be extremely effective for the identification of subclinical LV dysfunction in diabetic patients. It is hoped that the recognition of this condition will prompt specific therapy to prevent the development of overt LV dysfunction.     

Cardiac manifestations of Anderson-Fabry disease and efficacy of enzyme replacement therapy

Cardiac manifestations of Anderson-Fabry disease are usually part of a multiorgan involvement; they are frequently recognized in the young adult and increase morbidity and mortality. Cardiac complications, first hypertension and diastolic dysfunction, are observed in about half of patients and are accessible to the usual management of hypertension, heart failure, coronary artery disease, rhythm or conduction disturbances. However, the cardiac variant may present as an isolated or predominant cardiac involvement, with left ventricular hypertrophy being the most apparent sign, that could lead to the wrong diagnosis of ? idiopathic ? hypertrophic cardiomyopathy of sarcomeric origin (in 1-4% of cases, up to 6% in males before 40 years). However, in Fabry disease, hypertrophy is more often concentric without subaortic obstruction, while search for signs of Fabry disease (history of acroparesthesia or anhidrosis, renal dysfunction or stroke) should be systematic. Early identification of subjects with Fabry disease allows to check for target organ damage, family screening, genetic counseling and specific enzyme replacement therapy. The latter, in the absence of irreversible and extended myocardial fibrosis and/or severe renal dysfunction, is efficient on the progression of renal disease and cardiac hypertrophy and delayed in parallel the occurrence of a first renal, cardiac or neurologic event.     

Diltiazem reverses tissue Doppler velocity abnormalities in pre-clinical hypertrophic cardiomyopathy

BACKGROUND: Abnormalities in systolic and diastolic function shown by tissue Doppler imaging have been shown to be present in patients with hypertrophic cardiomyopathy who do not yet show clinical or echocardiographic evidence of the disease. These become more marked as left ventricular hypertrophy develops. We attempted to show that these abnormalities could be reversed by treatment with diltiazem. METHODS AND RESULTS: Six adults, who were carriers of a mutation involving the cardiac myosin binding, protein-C gene and who did not show clinical electrocardiographic or echocardiographic evidence of the disease were given a dose of 240mg of diltiazem daily. Tissue Doppler peak systolic and early diastolic velocities at the lateral mitral annulus were examined before treatment and at a mean of 8 weeks after starting treatment. Improvement in both parameters occurred with early diastolic velocities returning to normal and most systolic velocities also becoming normal. CONCLUSION: Diltiazem may have a role in helping to prevent abnormalities of function and perhaps the development of left ventricular hypertrophy in patients with pre-clinical hypertrophic cardiomyopathy.     

Tissue doppler imaging in hypertrophic cardiomyopathy without left ventricular hypertrophy

BACKGROUND: Diastolic function abnormalities determined by Doppler echo (especially those recorded by tissue velocity imaging) may be useful in determining carriers of an abnormal gene in hypertrophic cardiomyopathy who do not yet show clinical evidence of the disease. METHODS: In a single extended family, seven carriers of a mutation involving the cardiac myosin-binding protein C gene who did not show any features of the disease on 2-D echocardiography were examined by 2-D, M-mode Doppler and tissue Doppler imaging. The results were compared with a group of eight aged-matched people from the same family who did not have the gene mutation or clinical evidence of the disease. In both groups, as well as measuring the basal posterior and anteroseptal walls, the entire left ventricle was inspected for localised hypertrophy. RESULTS: Localised hypertrophy was absent from the left ventricle in both groups. There were significant differences in the tissue Doppler peak velocity measurements made at the lateral border of the mitral annulus in systole and especially early diastole. A systolic velocity of <10 cm/s was strongly suggestive of gene positivity and, if combined with an early mitral diastolic velocity (mitral E velocity) of <14 cm/s, was present only in gene-positive individuals. If the mitral E velocity was >14 cm/s, this was present only in gene-negative patients. CONCLUSION: Tissue Doppler imaging may be a valuable tool for screening first-degree relatives of patients with hypertrophic cardiomyopathy who do not show 2-D echo evidence of the disease.     

The heart in Anderson Fabry disease

Anderson Fabry disease is a life threatening, X-linked inborn metabolic defect of the lysosomal enzyme áalpha-galactosidase A. The deficiency of alpha-galactosidase A leads to a progressive accumulation of globotriaosylceramide (Gb(3)), the major glycosphingolipid substrate of the enzyme, within vulnerable cells, tissues, and organs, including the cardiovascular system. Cardiac involvement is frequent and patients with cardiac affection develop progressive hypertrophic infiltrative cardiomyopathy, valvular abnormalities, arrhythmias, and conduction abnormalities and may develop coronary heart disease. Hemizygous male patients have no detectable alpha-galactosidase A activity, while affected heterozygous females may have normal level of alpha-galactosidase A activity. Death occurs in male patients at 45 to 50 years, about 15 to 20 years earlier than in female patients due to a vicious circle from chronic renal insufficiency, arterial hypertension, atherosclerotic lesions and cerebrovascular hemorrhage or insults, and cardiomyopathy. Cardiac involvement in hetero- and hemizygotes will be discussed as well as the influence of enzyme replacement of alpha-galactosidase A.     

Fabry disease: clinic and enzymatic diagnosis of homozygous and heterozygous. New therapeutic prospects

Fabry disease is an X-linked recessive lysosomal storage disorder caused by a partial or complete deficiency of alpha-galactosidase A. Intracellular accumulation of globotriaosylceramide, the glycolipid substrate of this enzyme, leads to severe painful neuropathy with progressive renal, cardiovascular, and cerebrovascular dysfunction and early death. Men are predominantly affected but many female carriers have similar clinical involvement, including increased risk of stroke. Physical stigmata, such as angiokeratomas in skin and mucous membranes and characteristic benign corneal abnormalities, facilitate identification of Fabry disease. The finding of a marked decreased activity of (alpha-galactosidase A in plasma, white blood cells or cultured skin fibroblasts confirms the diagnosis. Treatment thus far has been symptomatic only. Etiology-based therapies are being developed that include enzyme replacement therapy, gene therapy, and substrate deprivation. The recently completed double-blind, placebo-controlled trials of intravenous infusions of (alpha-galactosidase A in patients with Fabry disease demonstrated the safety and efficacy of this treatment. We report a family with Fabry disease composed of hemicygous and heterocygous. The propositus developed chronic renal failure and received a cadaver renal transplant, which remained with adequate renal function during 15 years.     

Left ventricular systolic and diastolic function by echocardiogram in pseudoxanthoma elasticum

Pseudoxanthoma elasticum is an inherited systemic disease of connective tissue with possible cardiac involvement. Nineteen patients with pseudoxanthoma elasticum without a history of cardiac disease were investigated by echocardiography using standard measurements and tissue Doppler imaging. Systolic function was normal, but diastolic parameters were abnormal in 7 patients. Explanations for these abnormalities could be silent myocardial ischemia due to early coronary involvement and/or the direct consequences of ultrastructural defects of the elastic tissue of the heart.     

Fabry disease among hypertrophic cardiomyopathy of genetic origin

Primary hypertrophic cardiomyopathy is a relatively frequent disease (1/500) which results from a mutation in a gene encoding a sarcomeric protein. In a series of 184 cases, nearly half (46 %) were secondary to a mutation in one of the 4 following genes : MYBPC3, MYH7, TNNI3, TNNT2. In Fabry disease, an exclusive or nearly exclusive cardiac expression is possible and referred to as "cardiac variant". The hypertrophic cardiomyopathy of Fabry disease is usually unspecific. Two series reported a prevalence of Fabry disease of about 6% among male cases. An Italian series of 34 female cases with hypertrophic cardiomyopathy demonstrated that it was feasible to diagnose Fabry disease in females by screening for specific lesions in myocardial biopsies. We detected a patient who initially presented with a common hypertrophic cardiomyopathy except that his ECG showed depression of ST segment and inversion of T wave in leads D1, VL and in precordial leads. The family history revealed several affected relatives and female carriers. In conclusion, an isolated common hypertrophic cardiomyopathy may be secondary to Fabry disease. Male patients should be screened systemically for enzyme defect except in cases of father-to-son transmission. In females, an affected male relative should be searched for screening or the GLA gene should be sequenced. It is important to think about a putative Fabry disease in cases with hypertrophic cardiomyopathy not associated with any obvious cause.     

Fabry心肌病的诊断与治疗进展

法布里病（Fabry）是一种罕见的X染色体连锁遗传性疾病, 由于a-半乳糖苷酶A( alphagalactosidase A, GLA, 一种溶酶体酶)基因发生突变或缺失,引起体内GLA部分或全部缺乏,造成其代谢底物三己糖酰基鞘脂醇( globotriaosylceramide, Gb3)在人体各器官、组织蓄积,引起多个系统损害,其中心血管系统受累常见,主要表现为心肌肥厚、瓣膜损害、收缩/舒张功能减低,心律失常等,这些病变与患者心力衰竭、心源性猝死等密切相关。为了提高临床医生对Fabry病患者心脏受累表现的认识和诊治,本文将对Fabry 心肌病诊断与治疗的新进展作一综述。     

Pulse-cancellation echocardiography in Fabry disease diagnosis

Pulse-cancellation imaging is a novel echocardiographic imaging modality developed for detection of myocardial fibrosis. This technique cancels echocardiographic reflections from the normal myocardium but clearly displays the abnormal tissue. We describe, for the first time, pulse-cancellation echocardiography application in detecting Fabry disease myocardial involvement. We present the case where both pulse-cancellation imaging and cardiac MRI concurrently revealed myocardial deposits in a patient with genotypically confirmed Fabry disease.