Hypertrophic cardiomyopathy with ventricular septal hypertrophy localized to the apical region of the left ventricle (apical hypertrophic cardiomyopathy)

Comprehensive left ventricular outflow tract management beyond septal reduction to relieve obstruction

The surgical management of patients with hypertrophic obstructive cardiomyopathy can be extremely challenging. Relieving the left ventricular outflow tract obstruction in these patients is often achieved by performing a septal myectomy. However, in many instances, septal reduction alone is not enough to relieve the obstruction. Interventions on the sub-valvular apparatus, including the anomalous chordae tendineae and the abnormal papillary muscles, are often required. In this review, we summarize the embryology and the pathophysiology of the different elements that may contribute to the left ventricular outflow tract obstruction in the setting of hypertrophic obstructive cardiomyopathy. In addition, we highlight the different surgical procedures that a surgeon may adopt to relieve the left ventricular outflow tract obstruction, beyond the septal myectomy.

Future bradyarrhythmia in patients with hypertrophic cardiomyopathy

Background

A few studies to evaluate an incidence of bradyarrhythmia in patients with hypertrophic cardiomyopathy (HCM) have been reported.

Methods

We enrolled 161 patients with HCM to evaluate their bradyarrhythmia risk, especially the risk of patients who were at risk for sudden cardiac death (SCD) and eligible for implantation of an implantable cardiac defibrillator (ICD). We defined symptomatic bradyarrhythmia requiring a pacing therapy as a bradyarrhythmia event and collected the data on an occurrence of the event after the time of diagnosis of HCM. The incidence of bradyarrhythmia events was compared between patients with ICD indications (ICD-candidate group) and those without (non-ICD-candidate group). Furthermore, we investigated the associated factors with bradyarrhythmia events using a Cox proportional-hazards model.

Results

During 5.5 ± 4.4 years follow-up, bradyarrhythmia events occurred in 8% (13 patients) of whole patients, and in 15% of the ICD-candidate group (n = 74). In contrast, only 2 events (2%) occurred in the non-ICD-candidate group. The incidence of bradyarrhythmia in the ICD-candidate group was significantly higher than that in the non-ICD-candidate group (log-rank p = 0.015). In the ICD-candidate group, a Cox proportional-hazards model demonstrated that lower heart rate at the time of diagnosis (HR: 1.072, 95%CI: 1.012 to 1.135, p = 0.018), and an eligibility of ICD implantation for secondary prevention of SCD (HR: 9.092, 95%CI: 2.644 to 31.258, p < 0.001) were significantly associated with future bradyarrhythmia.

Conclusions

HCM patients with eligibility for ICD implantation, especially for secondary prevention of SCD, more frequently suffered from bradyarrhythmia events.

A change of heart: Transformation of the electrocardiogram in a patient with apical hypertrophic cardiomyopathy

An asymptomatic 83-year-old man with a history of hypertension, prior stroke with no residual deficits, and bilateral carotid artery stenosis, presented for evaluation prior to cataract surgery. His transthoracic echocardiogram was typical for apical hypertrophic cardiomyopathy (AHCM), and his electrocardiograms (ECG) showed large precordial R-waves and inverted T-waves, previously associated with AHCM, while his ECG 7 years earlier was normal. Mechanistic explanations for the developed ECG abnormalities, and their importance for the detection and monitoring of patients with AHCM are provided.

Hereditary heart disease: pathophysiology, clinical presentation, and animal models of HCM, RCM, and DCM associated with mutations in cardiac myosin light chains

Genetic cardiomyopathies, a group of cardiovascular disorders based on ventricular morphology and function, are among the leading causes of morbidity and mortality worldwide. Such genetically driven forms of hypertrophic (HCM), dilated (DCM), and restrictive (RCM) cardiomyopathies are chronic, debilitating diseases that result from biomechanical defects in cardiac muscle contraction and frequently progress to heart failure (HF). Locus and allelic heterogeneity, as well as clinical variability combined with genetic and phenotypic overlap between different cardiomyopathies, have challenged proper clinical prognosis and provided an incentive for identification of pathogenic variants. This review attempts to provide an overview of inherited cardiomyopathies with a focus on their genetic etiology in myosin regulatory (RLC) and essential (ELC) light chains, which are EF-hand protein family members with important structural and regulatory roles. From the clinical discovery of cardiomyopathy-linked light chain mutations in patients to an array of exploratory studies in animals, and reconstituted and recombinant systems, we have summarized the current state of knowledge on light chain mutations and how they induce physiological disease states via biochemical and biomechanical alterations at the molecular, tissue, and organ levels. Cardiac myosin RLC phosphorylation and the N-terminus ELC have been discussed as two important emerging modalities with important implications in the regulation of myosin motor function, and thus cardiac performance. A comprehensive understanding of such triggers is absolutely necessary for the development of target-specific rescue strategies to ameliorate or reverse the effects of myosin light chain-related inherited cardiomyopathies.

Left ventricular outflow tract obstruction in ICU patients

PURPOSE OF REVIEW

Left ventricular (LV) outflow tract (LVOT) obstruction (LVOTO) is not unusual in ICU patients particularly with septic shock.

RECENT FINDINGS

LVOT was first described in patients with hypertrophic cardiomyopathy and was defined as LV wall thickness at least 15 mm. LVOT is usually because of systolic anterior motion of the mitral valve. By convention, LVOTO is defined as an instantaneous peak Doppler LVOT pressure gradient at least 30 mmHg at rest or during physiological provocation such as Valsalva maneuver. Recently, it has been demonstrated that LVOT can be present in patients with severe hypovolemia or hyperkinesia with or without LV hypertrophy and can lead to hemodynamic compromise. LVOT is because of a combination of precipitating factors, which may or may not be associated with anatomical abnormalities. Decreased preload because of hypovolemia or decreased afterload because of septic shock, increased heart rate, and LV hyperkinesis produced by dobutamine infusion can induce a change of LV shape and induce LVOTO.

SUMMARY

LVOTO is not uncommon in ICU patients and can be observed at the early phase of septic shock. Treatment should include discontinuation of dobutamine infusion and fluid infusion. β blockers can be useful in this clinical situation.

Hypertrophic obstructive cardiomyopathy: review of surgical treatment

Hypertrophic cardiomyopathy ranks among the most common congenital cardiac diseases, affecting up to 1 in 200 of the general population. When it causes left ventricular outflow tract obstruction, treatment is guided to reduce symptoms and the risk of sudden cardiac death. Pharmacologic therapy is the first-line treatment, but when it fails, surgical myectomy or percutaneous ablation of the hypertrophic myocardium are the standard therapies to eliminate subaortic obstruction. Both surgical myectomy and percutaneous ablation are proven safe and effective treatments; however, myectomy is the gold standard with a significantly lower complication rate and more complete and lasting reduction of left ventricular outflow tract obstruction.

Yamaguchi syndrome presenting as atrioventricular nodal re-entrant tachycardia in an African-American patient

Apical hypertrophic cardiomyopathy (Yamaguchi syndrome) is a rare subtype of hypertrophic cardiomyopathy. The syndrome is more common in Japan where it was first described. Outside Asia, it is a very rare cause of hypertrophic cardiomyopathy. Apical hypertrophic cardiomyopathy is usually detected incidentally and has a good long-term outcome. We present a case of apical hypertrophic cardiomyopathy in an African-American patient manifesting as atrioventricular nodal re-entrant tachycardia.

Molecular mechanisms of cardiomyopathy phenotypes associated with myosin light chain mutations

We discuss here the potential mechanisms of action associated with hypertrophic (HCM) or dilated (DCM) cardiomyopathy causing mutations in the myosin regulatory (RLC) and essential (ELC) light chains. Specifically, we focus on four HCM mutations: RLC-A13T, RLC-K104E, ELC-A57G and ELC-M173V, and one DCM RLC-D94A mutation shown by population studies to cause different cardiomyopathy phenotypes in humans. Our studies indicate that RLC and ELC mutations lead to heart disease through different mechanisms with RLC mutations triggering alterations of the secondary structure of the RLC which further affect the structure and function of the lever arm domain and impose changes in the cross bridge cycling rates and myosin force generation ability. The ELC mutations exert their detrimental effects through changes in the interaction of the N-terminus of ELC with actin altering the cross talk between the thick and thin filaments and ultimately resulting in an altered force-pCa relationship. We also discuss the effect of mutations on myosin light chain phosphorylation. Exogenous myosin light chain phosphorylation and/or pseudo-phosphorylation were explored as potential rescue tools to treat hypertrophy-related cardiac phenotypes.

Pre-participation cardiovascular screening: is community screening using hand-held cardiac ultrasound feasible?

We evaluated the feasibility and costs of utilising hand-held cardiac ultrasound (HHCU) as part of a community-based pre-participation cardiovascular screening programme. Ninety-seven school children were screened using a personal history, a physical examination, a resting 12-lead electrocardiogram (ECG) and a HHCU. A consultant cardiologist independently reviewed and reported the data. Previously undiagnosed cardiovascular abnormalities were identified in nine participants (9%). An additional three participants (3%) were diagnosed with hypertension. The nine abnormalities were identified at a cost of £460 per finding, with a cost of £43 per participant screened. The marginal cost of adding a HHCU to the personal history, physical examination and ECG was £16 per participant. Pre-participation screening in the community using hand-held echocardiography is practical and inexpensive. The additional sensitivity and specificity provided by the ultrasound may enhance screening programmes, thereby reducing false positives and the need for expensive follow-up testing.

An unusual ST-segment elevation: apical hypertrophic cardiomyopathy shows the ace up its sleeve

Apical hypertrophic cardiomyopathy is part of the broad clinical and morphologic spectrum of hypertrophic cardiomyopathy. We report a patient with electrocardiographic abnormalities in whom acute coronary syndrome was excluded and apical hypertrophic cardiomyopathy was demonstrated by careful differential diagnosis.

Myocardial scarring on cardiovascular magnetic resonance in asymptomatic or minimally symptomatic patients with "pure" apical hypertrophic cardiomyopathy

BACKGROUND

Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) enables state-of-the-art in vivo evaluations of myocardial fibrosis. Although LGE patterns have been well described in asymmetrical septal hypertrophy, conflicting results have been reported regarding the characteristics of LGE in apical hypertrophic cardiomyopathy (ApHCM). This study was undertaken to determine 1) the frequency and distribution of LGE and 2) its prognostic implication in ApHCM.

METHODS

Forty patients with asymptomatic or minimally symptomatic pure ApHCM (age, 60.2 ± 10.4 years, 31 men) were prospectively enrolled. LGE images were acquired using the inversion recovery segmented spoiled-gradient echo and phase-sensitive inversion recovery sequence, and analyzed using a 17-segment model. Summing the planimetered LGE areas in all short axis slices yielded the total volume of late enhancement, which was subsequently presented as a proportion of total LV myocardium (% LGE).

RESULTS

Mean maximal apical wall thickness was 17.9±2.3 mm, and mean left ventricular (LV) ejection fraction was 67.7 ± 8.0%. All but one patient presented with electrocardiographic negative T wave inversion in anterolateral leads, with a mean maximum negative T wave of 7.2 ± 4.7 mm. Nine patients (22.5%) had giant negative T waves, defined as the amplitude of ≥ 10 mm, in electrocardiogram. LGE was detected in 130 segments of 30 patients (75.0%), occupying 4.9 ± 5.5% of LV myocardium. LGE was mainly detected at the junction between left and right ventricles in 12 (30%) and at the apex in 28 (70%), although LGE-positive areas were widely distributed, and not limited to the apex. Focal LGE at the non-hypertrophic LV segments was found in some ApHCM patients, even without LGE of hypertrophied apical segments. Over the 2-year follow-up, there was no one achieving the study end-point, defined as all-cause death, sudden cardiac death and hospitalization for heart failure.

CONCLUSIONS

LGE was frequently observed not only in the thickened apex of the heart but also in other LV segments, irrespective of the presence or absence of hypertrophy. The simple presence of LGE on CMR was not representative of adverse prognosis in this population.

Onset of apical hypertrophic cardiomyopathy in adulthood

The development of the hypertrophic cardiomyopathy (HC) phenotype with left ventricular (LV) hypertrophy usually occurs in adolescence, and documentation of patients with later onset of wall thickening during adulthood is rare. We report 4 patients with asymptomatic, nonobstructive HC (3 women and 1 man) who were studied with serial cardiovascular magnetic resonance imaging or echocardiography. In these patients, LV wall thickening, confined to the apex and the contiguous distal portions of the ventricular septum and free wall, appeared in midlife and beyond. These patients were >40, >50, or >70 years old when the hypertrophy became evident. The maximum LV wall thickness was 14 to 25 mm (mean 18), with a "spade" deformity of the distal chamber, associated with a nondilated cavity and normal ejection fraction (65% to 80%), in the absence of mitral valve systolic anterior motion. In each patient, similar electrocardiographic patterns with similar diffuse and marked T-wave inversion (with or without increased precordial voltages) preceded the appearance of the HC phenotype on the imaging studies. In conclusion, the recognition that the onset of LV hypertrophy in HC can be delayed well into adulthood (and even to advanced age) has important implications regarding the clinical screening practices for families, and suggests the potential value of extending prospective serial imaging beyond adolescence in some relatives. Electrocardiographic repolarization abnormalities can predict the future development of apical LV hypertrophy in adults with HC.

Clinical and echocardiographic predictors of outcomes in patients with apical hypertrophic cardiomyopathy

Apical hypertrophic cardiomyopathy (HC) is considered to have a favorable prognosis, but recent observations have suggested less benign clinical courses. We investigated the outcomes in patients with apical HC and evaluated the predictors. All 454 patients with apical HC (316 men, age 61 ± 11 years) were recruited. Major cardiovascular events (MACE) were defined as unplanned hospitalization because of heart failure, stroke, or cardiovascular mortality. The patients were divided into 2 groups: group 1 with MACE and group 2 without MACE. During the follow-up period (43 ± 20 months), the all-cause mortality rate was 9% (39 of 454), and 110 patients (25%) had MACE. The subjects in group 1 were older and a greater proportion had diabetes, hypertension, and atrial fibrillation. On the echocardiogram, the left atrial volume index (left atrial volume index 36 ± 17 vs 31 ± 12 ml/m(2)), transmitral E velocity (65 ± 17 vs 61 ± 16 cm/s), mitral annulus Ea velocity (4.5 ± 1.4 vs 5.1 ± 1.8 cm/s), Sa velocity (5.8 ± 1.4 vs 6.6 ± 1.4 cm/s), E/Ea ratio (15 ± 5 vs 13 ± 5), and right ventricular systolic pressure (31 ± 8 vs 28 ± 7 mm Hg) were significantly different between groups 1 and 2 (p <0.05 for all). The left atrial volume index (for each 1-ml/m(2) increase, hazard ratio 1.01, 95% confidence interval 1.00 to 1.03; p = 0.047), Sa velocity (hazard ratio 0.83, 95% confidence interval 0.72 to 0.96, p = 0.014), and E/Ea ratio (hazard ratio 1.04, 95% confidence interval 1.00 to 1.09, p = 0.030) were independent predictors of a poor prognosis, along with age and the presence of diabetes or hypertension. In conclusion, the clinical outcomes of patients with apical HC were less benign in older patients and in those with hypertension or diabetes. In addition, the left atrial volume index, Sa velocity, and E/Ea ratio were predicters of a poor prognosis in patients with apical HC.

Delayed-enhancement MRI of apical hypertrophic cardiomyopathy: assessment of the intramural distribution and comparison with clinical symptoms, ventricular arrhythmias, and cine MRI

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is reported to show patchy midwall myocardial hyperenhancement on delayed-enhancement magnetic resonance imaging (DE-MRI). The intramural distribution of myocardial hyperenhancement and its correlation with clinical symptoms, ventricular arrhythmias, and cardiac function have not been described forsymptomatic apical HCM.

PURPOSE

To evaluate the features and significance of myocardial hyperenhancement on DE-MRI insymptomatic apical HCM.

MATERIAL AND METHODS

Thirteen patients with symptomatic apical HCM and their 65 apical segments were investigated. Myocardial hyperenhancement and regional and global functional parameters were determined with MRI. We investigated the intramural distribution and frequencies of this myocardial hyperenhancement and compared them with the patients' clinical symptoms, the presence of ventricular arrhythmias, and cine MRI.

RESULTS

Eight (61.5%) patients with symptomatic apical HCM displayed apical myocardial hyperenhancement, and 22 (33.8%) of the 65 apical segments examined showed myocardial hyperenhancement. Of the myocardial hyperenhancement observed, 81.8% showed a subendocardial pattern.The hyperenhanced apical myocardium had a lower percentage of systolic myocardial thickening, and was associated with serious symptoms (e.g. syncope) and ventricular arrhythmias.

CONCLUSION

Patients with symptomatic apical HCMshowed myocardial hyperenhancement involving the subendocardial layer, which might be related to regional systolic dysfunction, serious clinical symptoms, and ventricular arrhythmias.

Apical hypertrophic cardiomyopathy in an adolescent

To our knowledge, this is one of the few reported cases of apical hypertrophic cardiomyopathy in an adolescent patient in the United States. We describe a clinical presentation of an adolescent male who presented for cardiac evaluation and was found to have an apical variant of hypertrophic cardiomyopathy.

Clinical profiles of hypertrophic cardiomyopathy with apical phenotype--comparison of pure-apical form and distal-dominant form

BACKGROUND

Hypertrophic cardiomyopathy (HCM) with an apical phenotype, in which hypertrophy of the myocardium predominantly involves the apex of the left ventricle, is not uncommon in Japan, but its morphologic variations are not well recognized. The aim of this study was to investigate if these variations have different clinical characteristics although they are still confused to be the same.

METHODS AND RESULTS

Patients with the apical phenotype were divided into 2 groups, the "pure-apical" form and the "distal-dominant" form, and their clinical profiles were compared. From the study cohort of 264 patients with HCM, 80 (30%) were classified as having the apical phenotype: 51 with the pure-apical form and 29 with the distal-dominant form. The age at diagnosis was approximately 60 years, and in both groups the majority were male. The distal-dominant group had a significantly larger left atrial diameter (43 vs 39 mm) and higher ratio of proven familial HCM (28 vs 6%), and were more symptomatic (New York Heart Association >or=3) at presentation (17 vs 0%). The event-free rate of cardiovascular events in patients with the distal-dominant form was significantly worse (log-rank P=0.012) than that in patients with the pure-apical form (follow-up period: asymptotically approximately 5 years).

CONCLUSIONS

The 2 phenotypes of apical HCM should be recognized and distinguished clinically.

Imaging studies in patients with heart failure: current and evolving technologies

Technological advances continue to expand the clinical role of echocardiography in the intensive care unit, particularly in patients with heart failure. It has many advantages over tomographic techniques such as echo cardiac magnetic resonance imaging and cardiac computed tomography, can provide rapid bedside cardiac assessment, and facilitate emergent decision-making for critically ill patients. Image quality problems in the intensive care setting have largely been overcome by the use of harmonic imaging, contrast opacification, and when indicated, transesophageal echocardiography. Newer techniques promise to advance the scope and prognostic power of echocardiography, and to expand the portability and availability of this tool.

Myosin essential light chain in health and disease

The essential light chain of myosin (ELC) is known to be important for structural stability of the alpha-helical lever arm domain of the myosin head, but its function in striated muscle contraction is poorly understood. Two ELC isoforms are expressed in fast skeletal muscle, a long isoform and its NH(2)-terminal approximately 40 amino acid shorter counterpart, whereas only the long ELC is observed in the heart. Biochemical and structural studies revealed that the NH(2)-terminus of the long ELC can make direct contacts with actin, but the effects of the ELC on the affinity of myosin for actin, ATPase, force, and the kinetics of force generating myosin cross-bridges are inconclusive. Myosin containing the long ELC has been shown to have slower cross-bridge kinetics than myosin with the short isoform. A difference was also reported among myosins with long isoforms. Increased shortening velocity was observed in atrial compared with ventricular muscle fibers. The common findings suggest that ELC provides the fine tuning of the myosin motor function, which is regulated in an isoform and tissue-dependent manner. The functional importance of the ELC is further implicated by the discovery of ELC mutations associated with Familial Hypertrophic Cardiomyopathy. The pathological phenotypes vary in severity, but more notably, almost all ELC mutations result in sudden cardiac death at a young age. This review summarizes the functional roles of striated muscle ELC in normal healthy muscle and in disease. Transgenic animal models and phenotypic characterization of ELC-mediated remodeling of the heart are also discussed.

Mutational screening of phospholamban gene in hypertrophic and idiopathic dilated cardiomyopathy and functional study of the PLN -42 C>G mutation

BACKGROUND

Phospholamban is an endogenous sarcoplasmic reticulum calcium ATPase inhibitor with a regulatory effect on cardiac contraction/relaxation coupling. Mutations in the phospholamban gene (PLN) have been associated with primary cardiomyopathies.

AIMS

To screen for PLN mutations in our population of patients with primary cardiomyopathies and to perform functional analysis of the mutations identified.

METHODS

We performed SSCP mutational screening and DNA sequencing of the PLN gene in 186 patients with either hypertrophic or dilated cardiomyopathy. To study promoter strength we constructed reporter plasmids containing the luciferase gene and performed transient transfection analysis in C6 and C2C12 cell lines.

RESULTS

The PLN -42 C>G mutation was found in one patient with late onset familial apical hypertrophic cardiomyopathy. This mutation decreased phospholamban promoter activity by 43% and 47%, in C6 and C2C12 cell lines respectively. One son had mild apical hypertrophic cardiomyopathy and carried the mutation, another son with normal ECG and echocardiogram also had the mutation.

CONCLUSION

The PLN -42 C>G mutation is associated with a benign form of apical hypertrophic cardiomyopathy in this family, though the presence of a healthy adult carrier suggests that other genetic and environmental factors could be involved. Otherwise, mutations in the PLN gene are not a frequent cause of cardiomyopathies in our population.

Cardiac arrest and ventricular tachycardia in Japanese-type apical hypertrophic cardiomyopathy

Apical hypertrophic cardiomyopathy (HCM) is a specific variant of HCM. This disease has been first described in Japan where the prevalence is much higher than in the western world. The prognosis of apical HCM with regard to sudden cardiac death is believed to be better than that of common HCM. We present, however, two male caucasian patients with apical HCM and malignant arrhythmias. Both patients had marked apical hypertrophy on echocardiography, 'giant' negative T-waves on the ECG and spade-like configuration of the left ventricle on angiography. The first patient had been successfully recussitated from cardiac arrest at the age of 52 years. The second patient had a syncope at the age of 42 years and had non-sustained ventricular tachycardia. In both cases, a cardioverter-defibrillator was implanted and treatment with verapamil was initiated. These observations suggest that the risk of sudden cardiac death might be increased not only in common HCM, but also in Japanese-type apical HCM.

Clinical features and outcome of patients with apical hypertrophic cardiomyopathy in Taiwan

OBJECTIVES

The aim of this study was to analyze clinical characteristics and the outcome of patients with apical hypertrophic cardiomyopathy (ApHCM) followed in a Taiwan tertiary referral medical center.

BACKGROUND

ApHCM is regarded as a subgroup of nonobstructive HCM that occurs largely in Japanese patients. The clinical features, gender differences and prognosis of the disease in Taiwan are poorly understood.

METHODS

A retrospective cohort study with 40 patients was performed. Diagnosis was based on the demonstration of left ventricular hypertrophy by echocardiography. Clinical features, cardiovascular morbidity and mortality were analyzed. Multiple logistic regression was used to adjust for potential confounding factors.

RESULTS

Among 40 patients, males predominated with a percentage of 75%. The female patients obviously had later onset of presentation (mean age +/- SD, 62.2 +/- 5.7 vs. 54.1 +/- 11.4 years; p = 0.038). During a mean follow-up of 72.2 +/- 60.1 months, there was no mortality. However, 13 patients (32.5%) had one or more major cardiovascular morbidities, the most frequent being syncope or near syncope (15%) and ischemic stroke-associated atrial fibrillation (10%). In a multivariate analysis, left atrial enlargement (odds ratio 5.85, 95% CI 1.15-29.40; p = 0.034) was the only predictor of cardiovascular morbidity.

CONCLUSIONS

Patients with ApHCM in Taiwan have a benign clinical course without association with sudden death and cardiovascular mortality. Left atrial enlargement was the only identified predictor of cardiovascular morbidity

Gene mutations in apical hypertrophic cardiomyopathy

BACKGROUND

Nonobstructive hypertrophy localized to the cardiac apex is an uncommon morphological variant of hypertrophic cardiomyopathy (HCM) that often is further distinguished by distinct giant negative T waves and a benign clinical course. The genetic relationship between HCM with typical hypertrophic morphology versus isolated apical hypertrophy is incompletely understood.

METHODS AND RESULTS

Genetic cause was investigated in 15 probands with apical hypertrophy by DNA sequence analyses of 9 sarcomere protein genes and 3 other genes (GLA, PRKAG2, and LAMP2) implicated in idiopathic cardiac hypertrophy. Six sarcomere gene mutations were found in 7 samples; no samples contained mutations in GLA, PRKAG2, or LAMP2. Clinical evaluations demonstrated familial apical HCM in 4 probands, and in 3 probands disease-causing mutations were identified. Two families shared a cardiac actin Glu101Lys missense mutation; all members of both families with clinical manifestations of HCM (n=16) had apical hypertrophy. An essential light chain missense mutation Met149Val caused apical or midventricular segment HCM in another proband and 5 family members, but 6 other affected relatives had typical HCM morphologies. No other sarcomere gene mutations identified in the remaining probands caused apical HCM in other family members.

CONCLUSIONS

Sarcomere protein gene mutations that cause apical hypertrophy rather than more common HCM morphologies reflect interactions among genetic etiology, background modifier genes, and/or hemodynamic factors. Only a limited number of sarcomere gene defects (eg, cardiac actin Glu101Lys) consistently produce apical HCM.

Prevalence of cardiac beta-myosin heavy chain gene mutations in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a frequent, autosomal-dominant cardiac disease and manifests predominantly as left ventricular hypertrophy. Mutations in the cardiac beta-myosin heavy chain gene (MYH7) are responsible for the disease in about 30% of cases where mutations were identified. We clinically evaluated a large group of 147 consecutive HCM patients from three cardiology centers in Germany, Poland, and Kyrgyzstan according to the same protocol. The DNA of the patients was systematically analyzed in the whole coding region of the MYH7 gene using PCR, single-strand conformation polymorphism analysis, and automated sequencing. Eleven different missense mutations (including seven novel ones) in 11 unrelated patients were identified, showing a mutation frequency of 7.5% in the study population. We further examined the families of five patients (three of German, one of Polish, and one of Kyrgyz origin) with 32 individuals in total. We observed a clear, age-dependent penetrance with onset of disease symptoms in the fourth decade of life. Genotype-phenotype correlations were different for each mutation, whereas the majority was associated with an intermediate/malign phenotype. In conclusion, we report a systematic molecular screening of the complete MYH7 gene in a large group of consecutive HCM patients, leading to a genetic diagnosis in 38 individuals. Information about the genotype in an individual from one family could be very useful for the clinician, especially when dealing with healthy relatives in doubt of their risk about developing HCM. The increasing application of genetic screening and the increasing knowledge about genotype-phenotype correlations will hopefully lead to an improved clinical management of HCM patients.

The pathology of hypertrophic cardiomyopathy

Sudden cardiac death (SCD) is devastating at any age, but even more so when the individual affected is young and asymptomatic, and the death is entirely unexpected. SCD is a catastrophic complication of hypertrophic cardiomyopathy (HCM) and may be the first manifestation of this disease. HCM is an inherited intrinsic disease of the myocardium characterized by left ventricular hypertrophy without chamber dilatation, in the absence of either a systemic or other cardiac disease, which may cause a similar magnitude of hypertrophy. HCM may be a clinically silent disease. Indeed, the pathologist may be the first to encounter a case of HCM at autopsy. HCM has wide-ranging implications for affected families, who will require cardiac screening and genetic counselling even if mutations are not known. Therefore, prompt and accurate diagnosis of HCM is vital. This review article will focus on the pathological diagnosis of HCM, recent advances in the genetics of this disease, and common pitfalls which may arise, leading to diagnostic uncertainty.

Hypertrophic Cardiomyopathy: A Case of Symptomatic Japanese Type Apical Hypertrophic Cardiomyopathy

A 61-year-old male patient was hospitalized due to the exertional angina pectoris. A diagnosis of apical hypertrophic cardiomyopathy was made by ECG (electrocardiography), echocardiographic, and coronary angiographic findings. This case was reported and related literature was reviewed because of its similarity to Japanese type apical hypertrophic cardiomyopathy (AHCMP) cases rarely seen outside Asia.

Resting "Solar Polar" map pattern and reduced apical flow reserve: characteristics of apical hypertrophic cardiomyopathy on SPECT myocardial perfusion imaging

BACKGROUND

Patients with apical hypertrophic cardiomyopathy (ACM) are often referred for myocardial perfusion single photon emission computed tomography (SPECT) as a result of marked T-wave inversion and chest pain syndromes. Stress perfusion defects have been reported in ACM, but the characteristic SPECT pattern as well as the typical findings on volume-weighted polar maps has not been described.

METHODS AND RESULTS

Dual-isotope rest (thallium 201) and exercise or adenosine stress (technetium 99m tetrofosmin) myocardial perfusion SPECT was performed in 11 patients with ACM, including 8 with either normal coronary arteriography (n = 5) or a low pretest probability of coronary artery disease (CAD) (n = 3), and 14 control patients with concentric left ventricular hypertrophy. An 8-pixel-diameter circular region of interest was used to quantitatively compare apical and septal counts on CEqual volume-weighted polar maps. A characteristic "Solar Polar" map pattern resulting from the increased apical counts was present in each ACM patient at rest, with a mean apical-septal ratio of 1.39 +/- 0.17 (range, 1.23-1.62, P <.01 vs concentric left ventricular hypertrophy group). With stress, there was a significant decrease in the apical-septal ratio (0.96 +/- 0.18, P <.001 vs rest) in the ACM subgroup without CAD.

CONCLUSION

Patients with ACM demonstrate a newly described "Solar Polar" map pattern at rest, as well as relative apical ischemia on the stress images even in the absence of CAD.

Comparison of prevalence of apical hypertrophic cardiomyopathy in Japan and the United States

The morphologic apical form of hypertrophic cardiomyopathy (HC), in which left ventricular (LV) wall thickening is confined to the most distal region at the apex, has been regarded as a phenotypic expression of nonobstructive HC largely unique to Japanese patients. To investigate this question further, we directly compared unselected and regional hospital-based cohorts of adult patients with HC ( > or =18 years of age) from Japan (Kochi; n=100) and from the United States (US) (Minneapolis; n=361). Japanese and American patients with HC had similar clinical features and did not differ significantly with regard to the severity of symptoms and frequency of outflow obstruction. Although Japanese and American patients also showed similar maximum LV thickness, they differed significantly with respect to the distribution of LV hypertrophy. In particular, the segmental form of HC, with hypertrophy confined to the LV apex, was more frequent in Japanese patients (i.e., apical HC, 15% in Japan vs 3% in US, p<0.0001). Giant negative T waves were also more common in Japanese patients with HC (26% vs 2%, p<0.001), including those with the apical form (64% vs. 30%, p<0.05). Each patient with apical HC had either no or only mild symptoms, and all survived. The morphologic form of nonobstructive HC with hypertrophy limited to the LV apex (apical form of HC) was 5 times more common in an unselected Japanese population. These findings document variability in the phenotypic expression of HC between countries and races, which may be due to differences in environmental factors or genetic background. Patients with the apical form of HC had a benign clinical course.

Cardiac muscle cell disorganization in apical hypertrophic cardiomyopathy: a cardiac biopsy study

Apical hypertrophic cardiomyopathy has been divided into two entities: apical asymmetric septal hypertrophy (apical ASH) and apical symmetric hypertrophy (AH). The latter differs clinically from hypertrophic cardiomyopathy (HCM) with ASH, and it is unclear whether AH represents a distinct subtype of HCM. In the present study, the presence or absence and the extent of cardiac muscle cell disorganization, a histologic characteristic of HCM, were compared in patients with AH (n = 10) and ASH (n = 29) in whom cardiac biopsy specimens were obtained from the left ventricular apex and interventricular septum. Disorganization was graded as (1+) in only 1 patient in the AH group and (-) in the remaining 9. In contrast, in the ASH group disorganization was graded as (1+) in 15 patients, (2+) in 7, (3+) in 3, and (-) in only 4 (P < 0.0001). Thus, it was observed that in AH disorganization is virtually absent or at most limited to a very narrow area. It is concluded from a histological stand point as well that the type of apical hypertrophic cardiomyopathy showing apical symmetric hypertrophy differs from usual HCM.

Quantitative diagnosis of apical cardiomyopathy using contrast echocardiography

BACKGROUND

The echocardiographic diagnosis of apical hypertrophic cardiomyopathy (ACM) has been limited by the frequent inability to visualize the apical endocardium. We hypothesized that the use of contrast agents in patients with suspected ACM, but nondiagnostic echocardiographic studies, would allow quantitative diagnosis.

METHODS

Contrast enhancement was performed in 26 patients with nondiagnostic transthoracic echocardiograms (TTEs) for the diagnosis of ACM; 6 patients with suspected ACM based on unexplained symmetric precordial T-wave inversions and increased apical tracer uptake on single-photon emission computed tomography (SPECT) scans, 10 patients with normal electrocardiogram (ECG) readings and no history of hypertension (healthy group), and 10 patients with hypertension and ECG criteria for left ventricular hypertrophy (LVH group). Images were obtained with Optison (Mallinckrodt Medical; IV, 1.0 mL) using harmonic imaging and low mechanical index. Posterior (PW) and septal wall (SW) thicknesses were measured at end-diastole in the parasternal long-axis view. Apical wall thickness (A) was measured from the contrast-enhanced apical endocardium to the visceral epicardial surface in the apical 4-chamber view. A/PW and A/SW ratios were calculated for each group. Asymmetric apical hypertrophy was defined as an A/PW ratio greater than 1.5.

RESULTS

Contrast-enhanced apical thickness was greater than 2.0 cm in all patients in the suspected ACM group but less than 1.2 cm in all patients in the LVH and healthy groups. In all 6 patients in the suspected ACM group, A/PW and A/SW ratios were greater than 1.5. No patient in the healthy or LVH groups had thickness ratios greater than 0.85.

CONCLUSION

Contrast echocardiography allows quantitative diagnosis of ACM in patients with suggestive ECG and SPECT but nondiagnostic TTEs. This study suggests that contrast echocardiography should be performed before using more expensive or invasive diagnostic testing for this condition.

Long-term outcome in patients with apical hypertrophic cardiomyopathy

OBJECTIVES

The aim of this study was to describe long-term outcome in patients with apical hypertrophic cardiomyopathy (ApHCM) followed in a tertiary referral center.

BACKGROUND

Apical hypertrophic cardiomyopathy is a relatively rare form of hypertrophic cardiomyopathy (HCM), first described in Japan. Initial reports, based on a limited number of patients, emphasized the benign nature of this condition.

METHODS

A retrospective study of 105 patients with ApHCM diagnosed at the Toronto General Hospital from 1975 to 2000 was performed. Symptoms, clinical findings, mortality and cardiovascular morbidity were analyzed.

RESULTS

The mean age at presentation was 41.4 +/- 14.5 years. During a mean follow-up of 13.6 +/- 8.3 years from presentation, cardiovascular mortality was 1.9% (2/105) and annual cardiovascular mortality was 0.1%. Overall survival was 95% at 15 years. Thirty-two patients (30%) had one or more major morbid events, the most frequent being atrial fibrillation (12%) and myocardial infarction (10%). Probability of survival without morbid events was 74% at 15 years. Three predictors of cardiovascular morbidity were identified: age at presentation <41 years, left atrial enlargement, and New York Heart Association (NYHA) class > or = II at baseline. Forty-four percent of the patients were asymptomatic at the time of last follow-up.

CONCLUSIONS

Apical hypertrophic cardiomyopathy in North American patients is not associated with sudden cardiac death and has a benign prognosis in terms of cardiovascular mortality. Nevertheless, one third of these patients experience serious cardiovascular complications, such as myocardial infarction and arrhythmias. These data are likely to influence the counseling and management of patients with ApHCM.

Impaired retention of technetium-99m tetrofosmin in hypertrophic cardiomyopathy

The purpose of this study was to determine whether myocardial imaging using technetium-99m tetrofosmin can noninvasively identify myocardial damage in hypertrophic cardiomyopathy (HC). The study consisted of 10 patients with apical HC, 10 with asymmetric septal HC (ASH) group, 5 with dilated cardiomyopathy (DC)-like group, and 20 healthy subjects. With use of a bull's-eye map of single-photon emission computed tomographic imaging, the total defect score of tetrofosmin and the washout rate were assessed in 5 segments (septum, and anterior, lateral, and inferior walls, and apex) of the left ventricle. A localized increase in defect score and washout rate was observed in the hypertrophied region in the group with apical HC. An increased washout rate was observed in the ASH group regardless of hypertrophy, suggesting that tetrofosmin retention by the mitochondria was impaired in the entire left ventricular wall. The washout rate was further increased at all segments in the DC-like group versus the ASH group. Tetrofosmin retention by mitochondria was impaired in the entire left ventricular wall in the ASH group and was increased further in the DC-like group. The dysfunction of myocardial cells was limited to the hypertrophied region in the apical HC group.

Diagnosis of apical hypertrophic cardiomyopathy using magnetic resonance imaging

Apical hypertrophic cardiomyopathy is an uncommon variant of non-obstructive hypertrophic cardiomyopathy with low prevalence outside East Asia. A case is reported of a non-Asian (European) 51 year old man with characteristic ECG and morphological changes of apical hypertrophic cardiomyopathy. Although the patient underwent catheterisation three years previously because of suggested coronary ischaemic heart disease, apical hypertrophic cardiomyopathy was not diagnosed. More recently, a regional wall motion abnormality was noticed at the apex on echocardiography. To rule out an ischaemic injury a stress perfusion scintigraphy was performed; no perfusion defect was present but an apical tracer enhancement was noted. Further evaluation by magnetic resonance imaging revealed the pathognomonic "ace of spades" configuration of the left ventricle with systolic obliteration of the apical region, which led to the diagnosis of apical hypertrophic cardiomyopathy.

Apical hypertrophic cardiomyopathy and hepatitis C virus infection

The familial form of hypertrophic cardiomyopathy (HCM) is attributed to mutations in the genes for contractile proteins, but the etiology of non-familial form remains unknown. This study was designed to examine the clinical features, histopathologic changes, and hepatitis C virus (HCV) genomes in patients with HCM associated with HCV infection. Anti-HCV antibody was present in the sera of 9 of 65 patients (13.8%) with HCM versus 2.41% in a control population of voluntary blood donors in Japan, a statistically significant difference (p<0.0001). Among these 9 patients, 6 had ace-of-spades-shaped deformities of the left ventricle with apical hypertrophy. Myocardial fibrosis was found in all patients, and mild cellular infiltration was observed in 5 patients. Type 1b HCV RNA was present in the sera of 5 of the 9 patients. The copy number of HCV was 5.5x10(3)-8.6x10(5) genomes/ml serum, and multiple clones of HCV were detected in the sera of each patient by an analysis of the hypervariable regions using fluorescent single-strand conformation polymorphism. Positive strands of HCV were found in the hearts of 5 patients, and negative strands in the hearts of 2 patients. A high prevalence of HCV infection was found in patients with HCM, particularly of the apical variety, suggesting that HCV is an important causal agent in the pathogenesis of the disease.

Morphological onset and early diagnosis in apical hypertrophic cardiomyopathy: a long term analysis with nuclear magnetic resonance imaging

OBJECTIVES

A long-term follow-up study with nuclear magnetic resonance (NMR) imaging was undertaken to detect the morphological onset and to establish the early diagnosis in apical hypertrophic cardiomyopathy (HCM).

BACKGROUND

A spadelike configuration on left ventriculogram (LVG) is regarded as a diagnostic criterion for the classical apical HCM. There also exists a segmented hypertrophy at the apical level without indicating the spadelike features (a nonspade configuration). To detect the hypertrophied myocardium of the nonspade configuration, circumferential scrutiny of the apex is required. Although both configurations can be underlying causes of giant negative T waves, etiological relationship between the two is not clarified.

METHODS

The criteria for the spadelike configuration defined on left ventricular short-axis NMR images were as follows: (apical maximal thickness > or = 15 mm), (apical anterior thickness over basal anterior thickness > or = 1.3) and (apical posterior thickness over basal posterior thickness > or =1.3). Thirteen patients who had predominant hypertrophy (> or = 15 mm) at the apical level without the spadelike configuration underwent NMR imaging twice before and after 54+/-10 months' follow-up.

RESULTS

Apical hypertrophy that had been confined to the lateral wall in four, the anterior-lateral wall in two, and the septal-anterior wall in one developed to become circumferential hypertrophy that fulfilled the criteria for the spadelike configuration after the follow-up period.

CONCLUSIONS

The spadelike configuration can begin with the nonspade configuration and therefore, both can constitute a single disease entity of apical HCM. The early diagnosis of apical HCM can be achieved by identifying the hypertrophy frequently confined to the lateral wall at the apical level.

Pacing in distal left ventricular hypertrophic cardiomyopathy

We report the case of an 85-year-old woman with distal LV hypertrophy resulting in an intraventricular pressure gradient and incomplete systolic emptying who benefited from permanent DDD pacing. Our experience based on this case suggests that permanent dual chamber pacing might be a safe and effective therapy also in symptomatic patients with the rare form of hypertrophic cardiomyopathy with left mid-ventricular obstruction resulting in incomplete emptying of the apical portion of the LV and a significant intraventricular pressure gradient that was not responding to pharmacological therapy.

Visualization of clear echocardiographic images with near field noise reduction technique: experimental study and clinical experience

BACKGROUND

With transthoracic echocardiography, it is sometimes difficult to obtain a clear image of the apical portion of the heart because of noise near the transducer. To reduce this artifact, we have developed a new technique (near field noise reduction, NFNR) based on the digital filtering by using radiofrequency signals. This technique may be useful for the accurate measurement of the wall thickness of the myocardium in the near field. The objectives of these studies were (1) to determine the accuracy of this new technique for the measurement of wall thickness in the experimental study and (2) to determine whether the improvement in the image quality in the apical portion can be obtained in the clinical setting by using the NFNR technique.

EXPERIMENTAL STUDY

By using the NFNR technique, we measured wall thickness of three kinds of phantoms (wall thickness 9.0, 14.0, and 21.0 mm) moving at various velocities (5 to 80 mm/sec) in the water bath with artifact produced by a single probe. It was difficult to obtain clear echocardiographic images of the phantom and measure its wall thickness because of the artifact. By using the NFNR technique, on the other hand, the same phantom was clearly imaged. It was possible to measure the wall thickness of each phantom at each moving velocity with the NFNR technique. Mean differences between the echocardiographic measurement and actual value of wall thickness in each phantom model (9.0, 14.0, and 21.0 mm) were 0.04 +/- 0.58 mm, 0.09 +/- 0.58 mm, and -0.02 +/- 0.24 mm, respectively.

CLINICAL STUDY

We studied 25 initial patients in whom the near field was not clearly imaged in apical views by conventional echocardiography because of near field noise. Apical four-chamber or two-chamber views were obtained with and without the NFNR technique. Two observers independently graded endocardial visualization for the 50 segments by using a three-point scale (0 = endocardium not seen, 1 = seen in part but not all of the segment, 2 = endocardium seen along entire segment). The mean segment score in the imaging with the NFNR technique was significantly higher than that without the NFNR technique (observer 1: 1.8 +/- 0.7 vs 1.2 +/- 0.8, p < 0.01; observer 2: 1.6 +/- 0.7 vs 1.2 +/- 0.8, p < 0.01).

CONCLUSIONS

The newly developed NFNR technique provides clear echocardiographic images and accurate wall thickness measurement in the experimental model even when it is difficult to obtain clear images because of the artifact. This new technique will be useful in the reduction of near field noise in the clinical setting.

Do repolarization abnormalities in hypertrophic cardiomyopathy represent impaired fatty acid utilization? An observation with QRST isointegral maps

To identify the clinical significance of the isointegral body surface map of the QRST interval (QRST map) and the occurrence of repolarization abnormalities in patients with hypertrophic cardiomyopathy (HCM), the QRST map and signal-averaged electrocardiogram were evaluated in 50 patients with HCM, in 33 of whom the results were compared with nuclear images both for radioiodine-labeled fatty acid metabolism and for radiothallium perfusion. The QRST departure map was used to determine two parameters of difference between patient and control recordings: the subnormal area (the number of lead points at which the departure index values were negative and lay more than 2 SDs from the mean of the normal control group) and the subnormal minimum (the absolute value of the minimum in the departure map). Late potentials were detected in 6 (12%) of the 50 patients; they were observed in 3 of the 5 patients with dilated-phase HCM but in only 3 (7%) of the other 45 patients. The subnormal area and minimum values were lower in nonobstructive HCM than in dilated-phase HCM. Of the 33 patients examined by myocardial imaging, 28 (33%) had a filling defect or decreased uptake, as shown on fatty acid metabolic images, and 10 of the 28 also showed abnormal myocardial perfusion images, while the 18 others showed normal perfusion images. These 28 patients showed significantly larger values of the subnormal area and minimum than patients with normal results in both image tests, regardless of whether or not myocardial perfusion imaging abnormalities were present. The localization of filling defects or of decreased uptake presented in fatty acid metabolic images corresponded to the position of the minimum on the QRST departure map. These results suggest that the QRST map is useful for detection of repolarization abnormalities in HCM and that these abnormalities are highly related to impaired fatty acid utilization of the myocardium.

Apical hypertrophic cardiomyopathy: a study of 14 patients and their first degree relatives

Although apical hypertrophic cardiomyopathy is generally accepted as a form of hypertrophic cardiomyopathy, its underlying genetic factors, clinical course and complications may be different. The characteristics of 14 Brazilian patients with a diagnosis of apical hypertrophic cardiomyopathy are described. Symptoms were frequent and abnormal filling of the left ventricle by Doppler criteria was recorded in all patients. Rest electrocardiograms showed giant negative T waves in 5 patients, all had low exercise capacity on an exercise stress test while significant arrhythmias were detected by 24-h ambulatory monitoring in just one patient. Forty-eight first degree relatives were studied and 3 had some form of hypertrophy of the left ventricle as seen by echocardiography. Apical hypertrophic cardiomyopathy in Brazilians seems to be expressed somewhat differently from that reported in Japanese patients, since "giant' T waves are less frequent and women more involved.