Hypertrophic Cardiomyopathy in Saudi Arabia: A Systematic Review of the Epidemiological, Clinical, and Imaging Features

BACKGROUND

A systematic review was performed to deliver a critical view of clinical and research practice on hypertrophic cardiomyopathy (HCM) in Saudi Arabia. Scopus, PubMed, and Google Scholar databases were searched for original articles reporting clinical and/or imaging findings among HCM patients in Saudi Arabia. Of 559 records identified, 3 studies and 1 abstract were included, involving 169 patients.

METHODS

The mean age ranged between 40and 56 years, up to 93.3% were males. A family history of HCM was reported in one study (5%), and sudden cardiac death was investigated in two studies (9% and 13%). Dyspnea was the most frequent symptom (60-68.7%) reported, followed by chest pain (12.5%-73.3%).

RESULTS

Regarding complications, atrial fibrillation was reported among 0-25% of the patients, mitral regurgitations among 13.3-50%, and ventricular tachycardia among 5-12.5%. Imaging parameters were inadequately documented and suggested a high prevalence of left atrial enlargement, SVI + RV5 > 35 mm, blocks, and asymmetric septal hypertrophy.

CONCLUSION

The ejection fraction was reported by two studies with a mean±SD of 68±13% and 77.2±8.07%. The researchers stress the paucity, low quality, and disparity in time of original studies about HCM in Saudi Arabia and recommend conducting national multicenter studies, with appropriate design, notably using screening-based recruitment methods.

A novel nonsense mutation in TNNT2 in a Chinese pedigree with hypertrophic cardiomyopathy: A case report

RATIONALE

Hypertrophic cardiomyopathy (HCM) is an inherited myocardial disease and a common cause of sudden cardiac death, heart failure, atrial fibrillation and stroke. In families affected by HCM, genotyping is useful for identifying susceptible relatives. In the present study, we investigated the disease-causing mutations in a three-generation Chinese family with HCM using whole exome sequencing (WES).

PATIENT CONCERNS

The proband, a 50-year-old man, was diagnosed with HCM at the age of 41 years. He presented with an asymmetric hypertrophic interventricular septum and a maximum interventricular septum thickness of 18.04 mm. His third elder sister, niece and daughter were also clinically affected by HCM.

DIAGNOSIS

Autosomal dominant HCM.

INTERVENTIONS

Seven family members, including 4 affected members, accepted WES. The genetic variants were subsequently called using Genome Analysis Toolkit and annotated using the InterVar program. Following frequency filtration by the Genome Aggregation Database, the variants were evaluated using an in-house bioinformatics analysis pipeline.

OUTCOMES

HCM was transmitted as an autosomal dominant trait in the family. An extremely rare stop gained mutation, rs796925245 (g.1:201359630G>A, c.835C>T, p.Gln279Ter) in the troponin T2 (TNNT2) gene was identified as the disease-causing mutation. The stop gained mutation was predicted to result in a truncated troponin T protein in cardiac sarcomere. An adolescent family member who had normal echocardiographic measurements was found to carry the same disease-causing mutation.

LESSONS

A novel nonsense TNNT2 mutation was identified as the HCM-causing mutation in this Chinese pedigree. Since HCM shows a low penetrance by clinical criteria in adolescents, the adolescent mutation carrier, who is still clinically unaffected, should be offered routine follow-ups and sport activity recommendations to prevent adverse events including sudden cardiac death in the future.

CaMKII-mediated phosphorylation of RyR2 plays a crucial role in aberrant Ca2+ release as an arrhythmogenic substrate in cardiac troponin T-related familial hypertrophic cardiomyopathy

AIMS

Cardiac Troponin T (TnT) mutation-linked familial hypertrophic cardiomyopathy (FHC) is known to cause sudden cardiac death at a young age. Here, we investigated the role of the Ca²⁺ release channel of the cardiac sarcoplasmic reticulum (SR), ryanodine receptor (RyR2), in the pathogenic mechanism of lethal arrhythmia in FHC-related TnT-mutated transgenic mice (TG; TnT-delta160E).

METHODS AND RESULTS

In TG cardiomyocytes, the Ca²⁺ spark frequency (SpF) was much higher than that in non-TG cardiomyocytes. These differences were more pronounced in the presence of isoproterenol (ISO; 10 nM). This increase in SpF was largely reversed by a CaMKII inhibitor (KN-93), but not by a protein kinase A inhibitor (H89). CaMKII phosphorylation at Ser2814 in RyR2 was increased significantly in TG. Spontaneous Ca²⁺ transients (sCaTs) after cessation of a 1-5 Hz pacing, frequently observed in ISO-treated TG cardiomyocytes, were also attenuated by KN-93, but not by H89. The RyR2 stabilizer dantrolene attenuated Ca²⁺ sparks and sCaTs in ISO-treated TG cardiomyocytes, indicating that the mutation-linked aberrant Ca²⁺ release is mediated by destabilized RyR2.

CONCLUSIONS

In FHC-linked TnT-mutated hearts, RyR2 is susceptible to CaMKII-mediated phosphorylation, presumably because of a mutation-linked increase in diastolic [Ca²⁺]_i, causing aberrant Ca²⁺ release leading to lethal arrhythmia.

Optimized pacing mode for hypertrophic cardiomyopathy: Impact of ECG fusion during pacing

BACKGROUND

Electrocardiographic (ECG) fusion with intrinsic QRS could reduce the benefit of atrial synchronous biventricular pacing (AS-BiVP) in patients with hypertrophic obstructive cardiomyopathy (HOCM).

OBJECTIVES

The purpose of this study was to assess the benefit of AS-BiVP and the influence of ECG fusion for reduction of left ventricular outflow tract gradient (LVOTG) in these patients.

METHODS

Twenty-one symptomatic HOCM patients with severe LVOTG were included. Twelve patients were evaluated retrospectively for the prevalence of fusion and its influence on outcomes after AS-BiVP. Eleven patients (2 of the first population were also evaluated retrospectively) were prospectively included to evaluate the benefit of performing atrioventricular node ablation (AVNA) to achieve full ventricular capture if fusion was present during AS-BiVP.

RESULTS

Seven of the first 12 patients (58%) had ECG fusion. After 54 ± 24 months of AS-BiVP, the presence of fusion was associated with lower values for reduction of resting, dynamic LVOTG and New York Heart Association (NYHA) class. In the prospectively evaluated patients, after 12 months of follow-up, resting LVOTG decreased from 98 ± 39 to 39 ± 24 mm Hg (P = .008); dynamic LVOTG decreased from 112 ± 38 to 60 ± 24 mm Hg (P = .013); NYHA class decreased from 2.8 ± 0.4 to 1.7 ± 0.6 (P = .014); endurance time during constant work rate cycling exercise (80% of peak oxygen consumption) increased from 399 ± 148 to 691 ± 249 seconds (P = .046); quality of life improved from 46 ± 22 to 22 ± 20 points (P = .02); and brain natriuretic peptide levels decreased from 318 ± 238 to 152 ± 118 pg/mL (P = .09). Eight of the 11 prospectively evaluated patients (73%) needed AVNA, which further decreased LVOTG from 108 ± 40 mm Hg at baseline to 89 ± 29 mm Hg after BiVP to 54 ± 22 mm Hg after AVNA (P = .003).

CONCLUSION

As-BiVP that ensures no ECG fusion, by means of AVNA when needed, appears to be the optimal pacing mode in HOCM patients.

Dramatically different phenotypic expressions of hypertrophic cardiomyopathy in male cousins undergoing cardiac transplantation with identical disease-causing gene mutation

Described herein are certain findings in 2 male cousins who underwent cardiac transplantation for severe heart failure (HF), one of the diastolic type (ejection fraction ≈65%), and one of the systolic type (ejection fraction ≈20%), both the consequence of hypertrophic cardiomyopathy (HC), and each had identical disease-causing gene mutations. The implanted heart in one had normal-sized ventricular cavities and no grossly visible ventricular wall lesions (except in one papillary muscle) and the other patient had severely dilated ventricular cavities and multiple extensive ventricular wall scars. The heart mass and the age of onset of symptoms was similar in each patient. A number of other family members had evidence of HC.

The genetics of cardiac disease associated with sudden cardiac death: a paper from the 2011 William Beaumont Hospital Symposium on molecular pathology

Sudden cardiac death due to ventricular arrhythmia most commonly occurs in the setting of coronary artery disease. However, a number of inherited syndromes have now been identified that carry a significant risk of sudden cardiac death and that are disproportionately represented in the young. Arrhythmia in such conditions may result from genetically mediated structural heart disease (eg, hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy) or from altered function of cardiac ion channels in the absence of overt structural disease (eg, Brugada syndrome and long QT syndrome). The past 15 years have seen considerable progress in our understanding of the genetic underpinnings of these disorders. With the advent of clinical genetic testing as a routine part of clinical care, a new knowledge base is required of practicing cardiologists and genetic testing facilities, particularly related to the rational ordering of genetic testing and the interpretation of results. This review addresses the latest findings in regard to the genetic causes of inherited syndromes associated with sudden cardiac death and summarizes recently published guidelines for the genetic testing of affected individuals and their families.

The diagnosis of hypertrophic cardiomyopathy by cardiovascular magnetic resonance

Hypertrophic cardiomyopathy (HCM) is the most common genetic disease of the heart. HCM is characterized by a wide range of clinical expression, ranging from asymptomatic mutation carriers to sudden cardiac death as the first manifestation of the disease. Over 1000 mutations have been identified, classically in genes encoding sarcomeric proteins. Noninvasive imaging is central to the diagnosis of HCM and cardiovascular magnetic resonance (CMR) is increasingly used to characterize morphologic, functional and tissue abnormalities associated with HCM. The purpose of this review is to provide an overview of the clinical, pathological and imaging features relevant to understanding the diagnosis of HCM. The early and overt phenotypic expression of disease that may be identified by CMR is reviewed. Diastolic dysfunction may be an early marker of the disease, present in mutation carriers prior to the development of left ventricular hypertrophy (LVH). Late gadolinium enhancement by CMR is present in approximately 60% of HCM patients with LVH and may provide novel information regarding risk stratification in HCM. It is likely that integrating genetic advances with enhanced phenotypic characterization of HCM with novel CMR techniques will importantly improve our understanding of this complex disease.

Clinical utility of cardiovascular magnetic resonance in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is characterized by substantial genetic and phenotypic heterogeneity, leading to considerable diversity in clinical course including the most common cause of sudden death in young people and a determinant of heart failure symptoms in patients of any age. Traditionally, two-dimensional echocardiography has been the most reliable method for establishing a clinical diagnosis of HCM. However, cardiovascular magnetic resonance (CMR), with its high spatial resolution and tomographic imaging capability, has emerged as a technique particularly well suited to characterize the diverse phenotypic expression of this complex disease. For example, CMR is often superior to echocardiography for HCM diagnosis, by identifying areas of segmental hypertrophy (ie., anterolateral wall or apex) not reliably visualized by echocardiography (or underestimated in terms of extent). High-risk HCM patient subgroups identified with CMR include those with thin-walled scarred LV apical aneurysms (which prior to CMR imaging in HCM remained largely undetected), end-stage systolic dysfunction, and massive LV hypertrophy. CMR observations also suggest that the cardiomyopathic process in HCM is more diffuse than previously regarded, extending beyond the LV myocardium to include thickening of the right ventricular wall as well as substantial morphologic diversity with regard to papillary muscles and mitral valve. These findings have implications for management strategies in patients undergoing invasive septal reduction therapy. Among HCM family members, CMR has identified unique phenotypic markers of affected genetic status in the absence of LV hypertrophy including: myocardial crypts, elongated mitral valve leaflets and late gadolinium enhancement. The unique capability of contrast-enhanced CMR with late gadolinium enhancement to identify myocardial fibrosis has raised the expectation that this may represent a novel marker, which may enhance risk stratification. At this time, late gadolinium enhancement appears to be an important determinant of adverse LV remodeling associated with systolic dysfunction. However, the predictive significance of LGE for sudden death is incompletely resolved and ultimately future large prospective studies may provide greater insights into this issue. These observations underscore an important role for CMR in the contemporary assessment of patients with HCM, providing important information impacting diagnosis and clinical management strategies.

[Malignant form of familial hypertrophic cardiomyopathy complicated with ventricular fibrillation in siblings. Electrocardiogram in hypertrophic cardiomyopathy - a review]

A family with hypertrophic cardiomyopathy (HCM) (15-year-old boy, his 17-year-old sister and 45-year-old father) is described. The first sign of HCM was cardiac arrest (CA) due to ventricular fibrillation (VF) in a boy. A few months later sister of proband had the episode of CA due to VF. Both had implanted cardioverter-defibrillator (ICD). Echocardiography revealed HCM in both cases and in a father, who also received prophylactic ICD. During 24-month follow-up fast VT was observed in sister of proband. We review electrocardiographic changes in HCM and their correlation with magnetic resonance.

[Alcohol septal ablation and prevention of sudden cardiac death in patients with hypertrophic cardiomyopathy. A case report]

We discuss approaches to the treatment of patients with hypertrophic cardiomyopathy, problems of prevention of sudden cardiac death in subjects with this pathology, and present results of multicenter study assessing efficacy of cardioverter defibrillator implantation in patients with hypertrophic cardiomyopathy. Special attention is devoted to the method of alcohol septal ablation in patient with obstructive form of hypertrophic cardiomyopathy and discussion of indications to this intervention. Clinical case is presented demonstrating early and long time results of alcohol septal ablation of pronounced obstruction of left ventricular outflow tract in a woman with high risk of sudden cardiac death.

Mutation of the MYH7 gene in a child with hypertrophic cardiomyopathy and Wolff-Parkinson-White syndrome

Familial hypertrophic cardiomyopathy (HCM) displays autosomal dominant inheritance with incomplete penetration of defective genes. Data concerning the familial occurrence of ventricular preexcitation, i.e. Wolff-Parkinson-White (WPW) syndrome, also indicate autosomal dominant inheritance. In the literature, only a gene mutation on chromosome 7q3 has been described in familial HCM coexisting with WPW syndrome to date. The present paper describes the case of a 7-year-old boy with HCM and coexisting WPW syndrome. On his chromosome 14, molecular diagnostics revealed a C 9123 mutation (arginine changed into cysteine in position 453) in exon 14 in a copy of the gene for beta-myosin heavy chain (MYH7). It is the first known case of mutation of the MYH7 gene in a child with both HCM and WPW. Since no linkage between MYH7 mutation and HCM with WPW syndrome has been reported to date, we cannot conclude whether the observed mutation is a common cause for both diseases, or this patient presents an incidental co-occurrence of HCM (caused by MYH7 mutation) and WPW syndrome.

Mechanisms of reduced mitochondrial Ca2+ accumulation in failing hamster heart

Mitochondrial Ca(2+) plays important roles in the regulation of energy metabolism and cellular Ca(2+) homeostasis. In this study, we characterized mitochondrial Ca(2+) accumulation in Syrian hamster hearts with hereditary cardiomyopathy (strain BIO 14.6). Exposure of isolated mitochondria from 70 nM to 30 microM Ca(2+) ([Ca(2+)](o)) caused a concentration-dependent increase in intramitochondrial Ca(2+) concentrations ([Ca(2+)](m)). The [Ca(2+)](m) was significantly lower in cardiomyopathic (CMP) hamsters than in healthy hamsters when [Ca(2+)](o) was higher than 1 microM and a decrease of about 52% was detected at [Ca(2+)](o) of 30 microM (916 +/- 67 nM vs 1,932 +/- 132 nM in control). A possible mechanism responsible for the decreased mitochondrial Ca(2+) uptake in CMP hamsters is the depolarization of mitochondrial membrane potential (Delta psi (m)). Using a tetraphenylphosphonium (TPP(+)) electrode, the measured Delta psi (m) in failing heart mitochondria was -136 +/- 1.5 mV compared with -159 +/- 1.3 mV in controls. Analyses of mitochondrial respiratory chain demonstrated a significant impairment of complex I and complex IV activities in failing heart mitochondria. In summary, a less negative Delta psi (m) resulting from defects in the respiratory chain may lead to attenuated mitochondrial Ca(2+) accumulation, which in turn may contribute to the depressed energy production and myocardial contractility in this model of heart failure. In addition to other known impairments of ion transport in sarcoplasmic reticulum and plasma membrane, results from this paper on mitochondrial dysfunctions expand our understanding of the molecular mechanisms leading to heart failure.

Familial apical hypertrophic cardiomyopathy with aneurysmal evolution--an unusual form

The authors present the case of a 76-year-old patient with multiple vascular risk factors, admitted with acute coronary syndrome. The initial electrocardiogram was compatible with evolving anterior wall myocardial infarction and the echocardiogram showed an image interpreted in this context as left apical pseudoaneurysm. Complementary echocardiographic findings of atypical apical hypertrophy and echocardiographic screening performed on close relatives suggested apical hypertrophic cardiomyopathy as the most likely diagnosis, later confirmed by genetic study. This unusual presentation with evolution to ventricular aneurysm is probably due to progressive left ventricular apical remodeling and an echocardiographic image similar to that described points to the diagnosis of this entity. We emphasize the rarity of this phenotypic expression of apical hypertrophic cardiomyopathy, in particular with familial association.

[Diagnostic value of a two-dimensional echocardiographic score for left ventricular hypertrophy validated by the Imatron CT scan in familial hypertrophic cardiomyopathy]

The aim of this study was to validate a two-dimensional echocardiographic score for left ventricular hypertrophy in familial hypertrophic cardiomyopathy (HCM) by fast CT scan and to study the diagnostic value by an indexed threshold value in affected and genotyped families in comparison with the classical diagnostic method of maximal wall thickness (E max). The study was performed successively in two patient groups with HCM. The echo/CT scan population comprised 26 patients. They underwent echocardiography and Imatron CT scanning. The E max and 2D echo score (sum of the thickness of 4 segments) were measured by echocardiography and compared to the left ventricular mass obtained by the CT method. The 2D echo score was closely correlated to the CT left ventricular mass (r = 0.85) with a higher correlation coefficient than the E max (r = 0.78). The echo/generic population comprised 109 genotyped adults with an identified mutation. The E max and 2D echo score were measured. The genotype was the reference for diagnosis. A theoretical value of the 2D echo score was determined in healthy individuals by a multiple linear regression model of ages, sex and body surface area. A threshold value for abnormality was established after analysis of the ROC. The sensitivity and specificity were 63% and 100% respectively for E max and 73% and 96% respectively for the indexed 2D echo score. The improvement in sensitivity was marked in young adults (< 50 years) with 69% for the indexed 2D echo score versus 54% for E max, p < 0.04. The authors conclude that the indexed 2D score has been validated as an index of hypertrophy by the Imatron CT and has a better diagnostic value than E max, especially in young adults. This echocardiographic criterion could be proposed as an alternative diagnostic sign for screening families.

Fatal hypertrophic cardiomyopathy and nemaline myopathy associated with ACTA1 K336E mutation

We report on a 2-year-old male child with both nemaline myopathy and hypertrophic cardiomyopathy (HCM). Sequencing of the ACTA1 gene showed a "de novo" missense heterozygous mutation a>g in exon 7 (Lys336Glu). Two-dimensional electrophoresis showed 28% mutant actin present in his muscle biopsy. Actin was isolated from the muscle biopsy and examined by in vitro motility assay. The sliding speed was 13+/-3% less than normal and the affinity of actin for the Z-line protein alpha-actinin was reduced 10 fold. This is the first report on a hypertrophic cardiomyopathy associated with nemaline myopathy and an ACTA1 mutation.

Usefulness of MRI to demonstrate the mechanisms of myocardial ischemia in hypertrophic cardiomyopathy with myocardial bridge

We present a case of symptomatic primary hypertrophic cardiomyopathy (HCM) associated with myocardial bridging of the left anterior descending (LAD) artery and suspected ischemia that could be related either to LAD artery compression or to microvascular perfusion abnormalities. MRI demonstrated the morphological appearance of myocardial hypertrophy, and coronary MR angiography evidenced the myocardial bridge and its functional consequences with stress MR perfusion. In conclusion, as a non-invasive comprehensive imaging technique, MRI should be considered in identifying the mechanisms of myocardial ischemia in HCM with myocardial bridge.

[Left ventricular myocardial geometry in arterial hypertension in patients with stenosing cerebral atherosclerosis]

The aim of the study was to define more exactly correlations between circulatory disturbances in the common carotid artery (CCA) basin, and hemodynamic disturbances and structural myocardial remodeling in patients suffering from arterial hypertension (AH) and cerebral atherosclerosis. The subjects were 83 patients evaluated by means of carotid arterial Doppler ultrasonography and echoCG; the variables of central homodynamic were measured as well. The study revealed that patients with AH and moderate CCA stenosis displayed hyperkinetic hemodynamic type more often than patients with severe CCA stenosis, of whom hypodynamic hemodynamic type was more typical. Left ventricular (LV) myocardial remodeling was more frequent in the latter group of patients; asymmetric LV hypertrophy prevailed. The study shows that the process of remodeling, caused by dissociation between central and regional hemodynamics, develops together with the progress of atherosclerotic arterial lesion.

Diltiazem treatment prevents diastolic heart failure in mice with familial hypertrophic cardiomyopathy

BACKGROUND

The cardiac troponin T I79N mutation, linked to familial hypertrophic cardiomyopathy, carries a high risk of sudden cardiac death even in the absence of significant cardiac hypertrophy. The pathology underlying this mechanism has not yet been identified.

AIMS

To study the underlying mechanism of this phenomenon we characterized the left ventricular (LV) performance of transgenic mice carrying the human troponin T mutation I79N under basal and isoproterenol-induced stress conditions.

METHODS AND RESULTS

LV function was analyzed by recording pressure-volume loops using a microconductance catheter. Despite a hypercontractile systolic function under basal conditions TnT-I79N mice showed a diastolic dysfunction indicated by an increase in end-diastolic pressure-volume relationship (EDPVR), a load-independent factor of LV stiffness (0.06+/-0.01 vs. 0.02+/-0.01; P<0.05), when compared to mice expressing human wild-type troponin T (TnT-WT). TnT-I79N mutants developed severe diastolic heart failure and cardiac sudden death under isoproterenol stress. This was prevented after pretreatment with the L-type Ca2+ channel inhibitor diltiazem.

CONCLUSIONS

Diastolic dysfunction due to increased LV stiffness in TnT-I79N mice leads to severe primary diastolic heart failure and finally to cardiac sudden death, which can be prevented by diltiazem.

[Acute coronary syndrome without ST segment elevation in a patient with familial hypertrophic cardiomyopathy--a case report]

Acute coronary syndrome without ST segment elevation in a patient with familial hypertrophic cardiomyopathy. A case of a 46-year-old male with hypertrophic cardiomyopathy and cardioverter-defibrillator implanted due to a history of syncopal sustained ventricular tachycardia, is presented. The patient had undergone coronary angiography two years before current hospitalisation which showed normal coronary arteries. This time the patient was admitted to the hospital due to a typical chest pain. ECG showed predominantly paced QRS complexes and negative T waves in V2-V6 which were present on ECG recorded a few months earlier. Troponin I plasma concentration was significantly elevated. Coronary angiography revealed critical stenosis of the left anterior descending coronary artery which was successfully treated with angioplasty and stent implantation. Diagnosis and treatment of patients with hypertrophic cardiomyopathy are discussed.

Hypertrophy, fibrosis, and sudden cardiac death in response to pathological stimuli in mice with mutations in cardiac troponin T

BACKGROUND

Transgenic mouse models expressing a missense mutation (R92Q) or a splice donor site mutation (trunc) in the cardiac troponin T (cTnT) model familial hypertrophic cardiomyopathy (FHC) in humans. Although males from these strains share the unusual property of having significantly smaller ventricles and cardiac myocytes, they differ with regard to systolic function, fibrosis, and gene expression. Little is known about how these phenotypes affect the responses to additional pathological stimuli.

METHODS AND RESULTS

We tested the ability of hearts of both sexes of wild-type and mutant mice to respond to defined pathological, pharmacological, hypertrophic stimuli in vivo. Hearts of mutant cTnT models of both sexes were able to undergo hypertrophy in response to at least one stimulus, but the extent differed between the 2 mutants and was sex specific. Interestingly, the trunc-mutant mouse heart was resistant to the development of fibrosis in response to pharmacological stimuli. Stimulation with 2 adrenergic agonists led to sudden cardiac death of all male but not female mutant animals, which suggests altered adrenergic responsiveness in these 2 models of FHC.

CONCLUSIONS

Hypertrophic signaling is differentially affected by distinct mutations in cTnT and is sex modified. Hearts can respond with either an augmented hypertrophic and fibrotic response or a diminished hypertrophy and resistance to fibrosis. Sudden cardiac death is related to adrenergic stress and is independent of the development of fibrosis but occurred only in male mice. These results suggest that patients with certain TnT mutations may respond to certain pathological situations with a worsened phenotype.

Congenital hypertrophic cardiomyopathy, cataract, mitochondrial myopathy and defective oxidative phosphorylation in two siblings with Sengers-like syndrome

We describe two siblings with a Sengers-like syndrome, who presented with congenital hypertrophic cardiomyopathy, infantile cataract, mitochondrial myopathy, lactic acidosis and normal mental development. A mitochondrial adenine nucleotide translocator 1 (ANT1) defect was detected since the ANT1 protein was not detectable by immmunoblotting in muscle samples of the patients. Additionally to these features of classical Sengers syndrome (OMIM 212350), we found that the mitochondrial oxidative phosphorylation, measured by biochemical analysis, was severely compromised in skeletal muscle in both children. Biochemical and morphological analysis of the fibroblasts revealed normal results. The association of significantly decreased pyruvate oxidation rates, deficient energy production and decreased multiple mitochondrial enzyme-complex activities in the muscle samples of our patients is a new finding which differs from previous results in patients with Sengers syndrome.

CONCLUSION

we recommend a muscle biopsy and the biochemical analysis of the oxidative phosphorylation system in patients with muscle hypotonia, cardiomyopathy and congenital or infantile cataract.

Sengers disease: a rare association of hypertrophic cardiomyopathy and congenital cataracts

Hypertrophic cardiomyopathy is an uncommon childhood cardiac disease and can be primary or secondary. Several systemic diseases are known to be associated with this entity. Senger's disease is a mitochondrial disorder causing congenital cataracts lactic acidosis and skeletal and cardiac myopathy. Diagnosis should be kept in mind when routine neonatal eye screening reveals absent red reflex. The authors report a case of Sengers disease and discuss the underlying pathogenetic mechanisms.

Predictors of Outcome After Alcohol Septal Ablation Therapy in Patients With Hypertrophic Obstructive Cardiomyopathy

BACKGROUND

Alcohol septal ablation (ASA) therapy results in clinical and hemodynamic improvement in patients with hypertrophic obstructive cardiomyopathy. However, a subset remains symptomatic afterward, requiring additional procedures. We sought to examine the determinants of an unsatisfactory outcome, defined as unchanged symptoms with <50% reduction of baseline left ventricular outflow tract (LVOT) gradient.

METHODS AND RESULTS

Of 173 consecutive hypertrophic obstructive cardiomyopathy patients who underwent ASA, 39 had an unsatisfactory outcome after the first procedure. Patients with an unsatisfactory outcome had a higher baseline LVOT gradient, fewer septal arteries injected with ethanol, lower peak creatine kinase (CK), smaller septal area opacified by contrast echocardiography, and higher residual gradient in the catheterization laboratory after ASA (all P<0.05). Symptoms, septal thickness, mitral regurgitation severity, and ventricular function were not determinants of outcome. On multiple logistic regression, LVOT gradient reduction after ASA in the catheterization laboratory to > or =25 mm Hg (OR, 5.5; P=0.01) and peak CK <1300 U/L (OR, 2.5; P=0.04) were the independent predictors of an unsatisfactory outcome.

CONCLUSIONS

The residual LVOT gradient in the catheterization laboratory and peak CK leak after ASA are the independent predictors of ASA outcome.

Familial hypertrophic cardiomyopathy complicated by complete atrioventricular block

We described a patient with familial non-obstructive hypertrophic cardiomyopathy and complete atrioventricular block. A 27-year-old male was admitted to our institution with syncope. Electrocardiography demonstrated complete atrioventricular block. Two-dimensional echocardiography revealed non-obstructive hypertrophic cardiomyopathy. A temporary transvenous ventricular pacemaker was inserted urgently, and subsequently replaced by a permanent dual-chamber pacemaker. Meanwhile, non-obstructive hypertrophic cardiomyopathy was diagnosed in the mother, the aunt and one of the brothers of the patient in the screening of the family, but atrioventricular conduction block was not detected in them. In the electrophysiological study of the mother, inducible ventricular tachycardia was detected. The reason for diversity of the arrhythmias in the members of the same family with hypertrophic cardiomyopathy may be explained by penetrance. The phenotype of the familial hypertrophic cardiomyopathy is influenced by factors varying the penetrance, such as age and gender.

Uncommon cause of a common disease

Myocardial infarction is a common life-threatening condition. Multiple agents can be used to treat acute coronary syndrome (ACS). These therapeutic agents pose potential life-threatening complications when used outside the realm of the acute coronary syndrome. Hypertrophic cardiomyopathy (HCM) is a common inherited cardiac disorder, occurring in 1 in 500 individuals, which may mimic ACS. The hypertrophy most typically involves the septum in patients with HCM. As many as 25% of Japanese patients with HCM have predominately apical involvement. Apical hypertrophic cardiomyopathy (AHC) occurs in only 1 to 2% of the non-Japanese population. Despite its low incidence, physicians caring for patients with chest pain need to consider AHC in their differential diagnosis. We present the case of a patient with chest pain and electrocardiographic changes suggestive of ACS who was later found to have AHC.

[Amiodarone-induced thyrotoxicosis: case report and review of the literature]

We report a case of amiodarone-induced thyrotoxicosis, and a broad review of the literature. Amiodarone is a drug widely used in cardiovascular medicine. Since it is iodine-rich, it may cause changes in thyroid function tests in some patients under chronic treatment. In 14-18% of amiodarone-treated patients, there is overt thyroid dysfunction (hypothyroidism or thyrotoxicosis). We here describe thyrotoxicosis, which can be distinguished in two subtypes differing in pathogenesis and treatment. Type I is primarily related to an excess of iodine-induced thyroid hormone synthesis in an abnormal thyroid gland, and the main medical treatment consists of the simultaneous administration of thionamides and potassium perchlorate. Type II is due to amiodarone-related destructive thyroiditis and glucocorticoids are therapy of choice. Mixed forms frequently exist. Due to the low thyroidal iodine uptake, radioiodine therapy is usually not efficacious. Surgical treatment can be performed in cases resistant to medical therapy.

Tissue Doppler imaging predicts the development of hypertrophic cardiomyopathy in subjects with subclinical disease

BACKGROUND

Systolic (Sa) and diastolic (Ea) myocardial velocities measured by tissue Doppler (TD) imaging (TDI) recently were shown to be decreased in subjects who have mutations causing hypertrophic cardiomyopathy (HCM) but who do not have left ventricular (LV) hypertrophy. By studying these subjects at a later date, we sought to determine whether TDI predicts the subsequent evolution of the HCM phenotype.

METHODS AND RESULTS

Serial 2D and Doppler echocardiography were performed in 12 subjects (age range, 17 to 51 years) with HCM-causing mutations on 2 occasions: before development of hypertrophy and 2 years later. Twelve age- and gender-matched family members without mutations were included as control subjects. In those with mutations, mean septal thickness and LV mass were 1.07+/-0.14 cm and 103.0+/-11 g at baseline, respectively, and increased to 1.30+/-0.36 cm and 193.0+/-78 g at follow-up (P<0.01), with 6 subjects satisfying HCM diagnostic criteria. Sa and Ea velocities in those with mutations were lower compared with control subjects at baseline and follow-up (lateral Sa, 15+/-1.2 versus 8.2+/-2.1 cm/s; lateral Ea, 16.5+/-2.8 versus 8.1+/-2.3 cm/s; P<0.01). At 2 years, left atrial volume and pulmonary venous flow indices of LV filling pressures increased, whereas TD early and late diastolic velocities decreased (all P<0.05) in those with the mutations. Control subjects had no significant interval changes of the above parameters.

CONCLUSIONS

Subsequent development of HCM in subjects with initially reduced TD velocities establishes TDI as a reliable method for early identification of HCM mutation carriers.

Improvement in hypertrophic cardiomyopathy after significant weight loss: case report

A 17-year-old obese boy found to have familial apical hypertrophic cardiomyopathy on routine screening was enrolled in a weight loss program on the basis of the hypothesis that significant weight loss would improve his cardiac status. He was followed with serial dual-energy x-ray absorptiometry, electrocardiography, echocardiography, and blood pressure and pulse rate measurements. Within 1 year, he lost 49 kg, with a body mass index reduction from 43.6 to 28.1 kg/m2 and associated reductions in systolic blood pressure, diastolic blood pressure, pulse pressure, mean heart rate, rate pressure product, and echocardiographic indices of left ventricular mass that resulted in a change from the initial geometric finding of eccentric left ventricular hypertrophy to a "normal" left ventricular mass with minimal asymmetric apical left ventricular thickening. Significant weight loss in an obese adolescent with presumed familial apical hypertrophic cardiomyopathy was associated with striking improvement in cardiac functional indices, which could have profound implications for long-term cardiovascular risk.

Familial cardiomyopathies: significant causes of heart failure

Familial dilated cardiomyopathies (FDCMs) account for about one third of idiopathic dilated cardiomyopathies, yet clinicians under-appreciate their prevalence. Among the inherited cardiomyopathies, FDCMs account for the greatest burden of heart failure and its associated morbidities. This paper summarizes significant molecular-genetic data, and discusses clinical manifestations of the major inherited cardiomyopathies, and the importance of clinical and genetic screening. Suggestions are provided as to how to proceed with screening. The purpose of this paper is to update clinicians about this rapidly growing scientific field, and to encourage application of current evidence to their practices.

Cardiac adrenergic activity is associated with left ventricular hypertrophy in genetically homogeneous subjects with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic disease caused by mutations in genes encoding sarcomeric proteins. However, other genetic and possibly also environmental factors modify the phenotypic expression of left ventricular (LV) hypertrophy. The present study investigated whether cardiac adrenergic activity affects the severity of LV hypertrophy in genetically identical patients with HCM.

METHODS

The study population consisted of 21 patients with HCM caused by the Asp175Asn substitution of the alpha-tropomyosin gene (TPM1-Asp175Asn) and 9 healthy volunteers. LV mass and segmental wall thickness were measured with MRI. Presynaptic cardiac adrenergic activity was measured with (123)I-metaiodobenzylguanidine (MIBG) SPECT. Global and segmental washouts of (123)I-MIBG were calculated.

RESULTS

Global myocardial (123)I-MIBG washout was faster in patients with TPM1-Asp175Asn than in healthy volunteers (50% +/- 9% vs. 37% +/- 8%, P = 0.001). In linear regression analysis, global (123)I-MIBG washout was associated with the LV mass index and LV maximal wall thickness index in HCM patients (r = 0.512, P = 0.018, and r = 0.478, P = 0.028, respectively). The mean (123)I-MIBG washout was higher in LV segments >/= 15 mm thick than in LV segments < 15 mm thick (56 +/- 10 vs. 49% +/- 10%, P = 0.002).

CONCLUSION

In patients with HCM sharing the same causal gene defect, the degree of LV hypertrophy is related to (123)I-MIBG washout, suggesting that cardiac adrenergic activity modifies phenotypic expression in HCM.

Variable clinical manifestation of a novel missense mutation in the alpha-tropomyosin (TPM1) gene in familial hypertrophic cardiomyopathy

OBJECTIVES

This study was initiated to identify the disease-causing genetic defect in a family with hypertrophic cardiomyopathy (HCM) and high incidence of sudden death.

BACKGROUND

Familial hypertropic cardiomyopathy (FHC) is an autosomal dominant transmitted disorder that is genetically and clinically heterogeneous. Mutations in 11 genes have been associated with the pathogenesis of the disease.

METHODS

We studied a large FHC family, first by linkage analysis, to identify the gene involved, and subsequently screened the gene, encoding alpha-tropomyosin (TPM1), for mutations by using single-strand conformation polymorphism and sequencing analysis.

RESULTS

Twelve family members presented clinical features of HCM, five of whom died at young age, while others had only mild clinical features. Marker analysis showed linkage for the TPM1 gene on chromosome 15q22 (maximal logarithm of the odds score is 5.16, theta = 0); subsequently, a novel missense mutation (Glu62Gln) was identified.

CONCLUSIONS

The novel mutation identified in TPM1 is associated with the clinical features of cardiac hypertrophy in all but one genetically affected member of this large family. The clinical data suggest a malignant phenotype at young age with a variable clinical manifestation and penetrance at older age. The Glu62Gln mutation is the sixth TPM1 mutation identified as the cause of FHC, indicating that mutations in this gene are very rare. This is the first reported amino acid substitution at the f-position within the coiled-coil structure of the tropomyosin protein.

Coexistence of Familial Hypertrophic Cardiomyopathy and Vasospastic Angina Pectoris in Two Brothers

Two brothers had familial hypertrophic cardiomyopathy and vasospastic angina pectoris concurrently. Their family history showed that one of their sisters had hypertrophic cardiomyopathy and another brother died suddenly at age 52. The clinical diagnosis of hypertrophic cardiomyopathy was confirmed by an echocardiogram and left ventriculography. They had typical chest pain at rest, and a significant vasospasm of coronary arteries with chest pain and obvious ST-T changes in the electrocardiograms was provoked by intracoronary injection of acetylcholine in both patients. The administration of a calcium antagonist and nitrate was effective for ameliorating chest pain with no cardiovascular events during the follow up period of more than 3 years. Although underlying pathophysiologic abnormalities of familial hypertrophic cardiomyopathy and vasospastic angina pectoris are considered to be transmitted genetically, the genetic backgrounds of these cases remain to be clarified.

[Familial hypertrophic cardiomyopathy associated with Wolff-Parkinson-White syndrome revealing type II glycogenosis]

Symptoms of the late infantile form of type II glycogen storage disease are mainly due to functional impairment of skeletal muscle. Cardiac muscle can be involved in the late stage of the disease.

CASE REPORT

We report the cases of two siblings seven and 12 years old with type II glycogen storage disease. The initial symptoms were hypertrophic cardiomyopathy with Wolf-Parkinson-White syndrome.

CONCLUSION

Hypertrophic cardiomyopathy may be the form of presentation of the late infantile form of type II glycogen storage disease. The risk of sudden death is high.

Genetic polymorphisms in the renin-angiotensin-aldosterone system associated with expression of left ventricular hypertrophy in hypertrophic cardiomyopathy: a study of five polymorphic genes in a family with a disease causing mutation in the myosin binding protein C gene

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is an inherited disease of the sarcomere characterised clinically by myocardial hypertrophy and its consequences. Phenotypic expression is heterogeneous even within families with the same aetiological mutation and may be influenced by additional genetic factors.

OBJECTIVE

To determine the influence of genetic polymorphisms of the renin-angiotensin-aldosterone system (RAAS) on ECG and two dimensional echocardiographic left ventricular hypertrophy (LVH) in genetically identical patients with HCM.

PATIENTS AND METHODS

Polymorphisms of five RAAS components were determined in 26 gene carriers from a single family with HCM caused by a previously identified myosin binding protein C mutation. Genotypes associated with a higher activation status of the RAAS were labelled "pro-LVH genotypes".

RESULTS

There was a non-biased distribution of pro-LVH genotypes in the gene carriers. Those without pro-LVH genotypes did not manifest cardiac hypertrophy whereas gene carriers with pro-LVH genotypes did (mean (SD) left ventricular muscle mass 190 (48) v 320 (113), p = 0.002; interventricular septal thickness 11.5 (2.0) v 16.4 (6.7), p = 0.01; pathological ECG 0% (0 of 10) v 63% (10 of 16), respectively). Multivariate analysis controlling for age, sex, and hypertension confirmed an independent association between the presence of pro-LVH polymorphisms and left ventricular mass. When each polymorphism was assessed individually, carriers of each pro-LVH genotype had a significantly greater left ventricular mass than those with no pro-LVH mutation; these associations, with the exception of cardiac chymase A AA polymorphism (p = 0.06), remained significant in multivariate analysis.

CONCLUSION

Genetic polymorphisms of the RAAS influence penetrance and degree of LVH in 26 gene carriers from one family with HCM caused by a myosin binding protein C mutation.

Role of transvenous implantable cardioverter-defibrillators in preventing sudden cardiac death in children, adolescents, and young adults

OBJECTIVE

To evaluate the indications, underlying cardiac disorders, efficacy, and complications involved with transvenous implantable cardioverter-defibrillators (ICDs) in pediatric patients at the Mayo Clinic.

PATIENTS AND METHODS

The records of all patients aged 21 years or younger who underwent transvenous ICD placement at the Mayo Clinic, Rochester, Minn, were reviewed retrospectively.

RESULTS

Between March 1992 and September 2000, 16 patients (7 females; mean age, 15.4 years; range, 10-21 years) underwent transvenous ICD placement. The ICD was implanted for primary prevention of sudden cardiac death in 7 and for secondary prevention in 9. The underlying cardiac disorders included hypertrophic cardiomyopathy in 6 patients and congenital long QT syndrome in 6 patients. The mean +/- SD follow-up was 36+/-29 months (range, 5-108 months). There was no mortality. Seven patients (44%) received appropriate ICD therapy, including 6 of 9 who had ICDs placed for secondary prevention. Median time free from appropriate ICD discharge was 3 years (range, 0.2-9 years). Three patients (19%) experienced inappropriate ICD discharge. Two patients needed device replacement because of technical problems (lead fracture and device malfunction). Two patients developed pocket infection that required removal and reimplantation of the ICD.

CONCLUSION

In adolescents and young adults, transvenous ICDs may prevent sudden death but are not free of complications. Forty-four percent of this cohort received potentially life-saving ICD therapy, including two thirds who received an ICD for secondary prevention.