Evaluation of pathological criteria for diagnosis of hypertrophic cardiomyopathy

Morphological and Genetic Aspects for Post-Mortem Diagnosis of Hypertrophic Cardiomyopathy: A Systematic Review

Hypertrophic cardiomyopathy (HCM) is one of the most common genetic cardiovascular diseases, and it shows an autosomal dominant pattern of inheritance. HCM can be clinically silent, and sudden unexpected death due to malignant arrhythmias may be the first manifestation. Thus, the HCM diagnosis could be performed at a clinical and judicial autopsy and offer useful findings on morphological features; moreover, it could integrate the knowledge on the genetic aspect of the disease. This review aims to systematically analyze the literature on the main post-mortem investigations and the related findings of HCM to reach a well-characterized and stringent diagnosis; the review was performed using PubMed and Scopus databases. The articles on the post-mortem evaluation of HCM by gross and microscopic evaluation, imaging, and genetic test were selected; a total of 36 studies were included. HCM was described with a wide range of gross findings, and there were cases without morphological alterations. Myocyte hypertrophy, disarray, fibrosis, and small vessel disease were the main histological findings. The post-mortem genetic tests allowed the diagnosis to be reached in cases without morpho-structural abnormalities; clinical and forensic pathologists have a pivotal role in HCM diagnosis; they contribute to a better definition of the disease and also provide data on the genotype-phenotype correlation, which is useful for clinical research.

Clinicopathological and Genetic Profiles of Cases with Myocytes Disarray-Investigation for Establishing the Autopsy Diagnostic Criteria for Hypertrophic Cardiomyopathy

Myocyte disarray of >10% in the heart is broadly accepted as a diagnostic pitfall for hypertrophic cardiomyopathy (HCM) at postmortem. The present study aims to propose an additional diagnostic criterion of HCM. Heart specimens from 1387 serial forensic autopsy cases were examined. Cases with myocyte disarray were extracted and applied to morphometric analysis to determine the amount of myocyte disarray. Comprehensive genetic analysis by using next-generation sequencing was subsequently applied for cases with myocyte disarray. Fifteen cases with myocyte disarray were extracted as candidate cases (1.1%, 11 men and 4 women, aged 48–94 years). In terms of the cause of death, only 2 cases were cardiac or possible cardiac death, and the other was non-cardiac death. Six cases showed myocyte disarray of >10% and 3 cases showed myocyte disarray of 5% to 10%. The other 6 cases showed myocyte disarray of <5%. Nine rare variants in 5 HCM-related genes (MYBPC3, MYH7, MYH6, PRKAG2, and CAV3) were found in 8 of 9 cases with myocyte disarray of >5%. The remaining 1 and 6 cases with myocyte disarray of <5% did not have any such variant. Myocyte disarray of >5% with rare variants in related genes might be an appropriate postmortem diagnostic criterion for HCM, in addition to myocyte disarray of 10%.

Early Imaging Biomarker of Myocardial Glucose Adaptations in High-Fat-Diet-Induced Insulin Resistance Model by Using 18F-FDG PET and [U-13C]glucose Nuclear Magnetic Resonance Tracer

Background

High-fat diet (HFD) induces systemic insulin resistance leading to myocardial dysfunction. We aim to characterize the early adaptations of myocardial glucose utility to HFD-induced insulin resistance.

Methods

Male Sprague–Dawley rats were assigned into two groups, fed a regular chow diet or HFD ad libitum for 10 weeks. We used in vivo imaging of cardiac magnetic resonance (CMR), ¹⁸F-FDG PET, and ex vivo nuclear magnetic resonance (NMR) metabolomic analysis for the carbon-13-labeled glucose ([U-¹³C]Glc) perfused myocardium.

Results

As compared with controls, HFD rats had a higher ejection fraction and a smaller left ventricular end-systolic volume (P < 0.05), with SUV_max of myocardium on ¹⁸F-FDG PET significantly increased in 4 weeks (P < 0.005). The [U-¹³C]Glc probed the increased glucose uptake being metabolized into pyruvate and acetyl-CoA, undergoing oxidative phosphorylation via the tricarboxylic acid (TCA) cycle, and then synthesized into glutamic acid and glutamine, associated with overexpressed LC3B (P < 0.05).

Conclusions

HFD-induced IR associated with increased glucose utility undergoing oxidative phosphorylation via the TCA cycle in the myocardium is supported by overexpression of glucose transporter, acetyl-CoA synthase. Noninvasive imaging biomarker has potentials in detecting the metabolic perturbations prior to the decline of the left ventricular function.

Cardiac Magnetic Resonance and Computed Tomography in Hypertrophic Cardiomyopathy: an Update

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disease and represents the main cause of sudden death in young patients. Cardiac magnetic resonance (CMR) and cardiac computed tomography (CCT) are noninvasive imaging methods with high sensitivity and specificity, useful for the establishment of diagnosis and prognosis of HCM, and for the screening of patients with subclinical phenotypes. The improvement of image analysis by CMR and CCT offers the potential to promote interventions aiming at stopping the natural course of the disease. This study aims to describe the role of RCM and CCT in the diagnosis and prognosis of HCM, and how these methods can be used in the management of these patients.

[Myocardial regional thickness in patients with and without cardiomyopathy assessed by cardiac magnetic resonance]

OBJECTIVE

To explore regional differences in myocardial wall thickness (WT) among the most prevalent cardiomyopathies and in individuals without structural heart disease using cardiac magnetic resonance.

METHODS

Patients older than 18 years referred to cardiac magnetic resonance during the period between January 2014 and September 2014, with a diagnosis of hypertrophic cardiomyopathy, idiopathic dilated cardiomyopathy, ischemic cardiomyopathy, and myocarditis were retrospectively selected from our database.

RESULTS

One hundred twenty patients patients were included. The control group had an average WT of 5.9±1.1mm, with a WT index of 2.9±0.8. Significantly lower mean WT in the apical segments were identified in both the control group (basal 6.7±1.3 vs. mid 6.0±1.3 vs. apical 4.6±1.0mm, P<.0001) and in all evaluated cardiomyopathies (hypertrophic cardiomyopathy: basal 10.5±2.4 vs. mid 10.8±2.7 vs. apical 7.3±3.3mm, P<.0001; idiopathic dilated cardiomyopathy: basal 7.7±1.7 vs. mid 7.6±1.3 vs. apical 5.4±1.3mm, P<.0001; ischemic cardiomyopathy: basal 7.4±1.7 vs. mid 7.5±1.9 vs. apical 5.5±1.8mm, P<.0001; myocarditis: basal 7.1±1.5 vs. mid 6.4±1.1 vs. apical 5.1±0.8, P<.0001). Significant gender differences were also evident regarding the mean WT both in the control group (male 6.5±2.1 vs. female 5.2±1.7mm, P<.0001), as in hypertrophic cardiomyopathy (10.5±5.3 vs. 8.5±5.7mm, P<.0001) and myocarditis (6.6±2.0 vs. 5.2±1.6mm, P<.0001).

CONCLUSION

We found a relatively high prevalence of segments commonly deemed thinned among patients without structural heart disease. We also observed a marked asymmetry and longitudinal gradient in wall thickness both in controls and in the various cardiomyopathies evaluated.

Role of multimodality cardiac imaging in the management of patients with hypertrophic cardiomyopathy: an expert consensus of the European Association of Cardiovascular Imaging Endorsed by the Saudi Heart Association

Taking into account the complexity and limitations of clinical assessment in hypertrophic cardiomyopathy (HCM), imaging techniques play an essential role in the evaluation of patients with this disease. Thus, in HCM patients, imaging provides solutions for most clinical needs, from diagnosis to prognosis and risk stratification, from anatomical and functional assessment to ischaemia detection, from metabolic evaluation to monitoring of treatment modalities, from staging and clinical profiles to follow-up, and from family screening and preclinical diagnosis to differential diagnosis. Accordingly, a multimodality imaging (MMI) approach (including echocardiography, cardiac magnetic resonance, cardiac computed tomography, and cardiac nuclear imaging) is encouraged in the assessment of these patients. The choice of which technique to use should be based on a broad perspective and expert knowledge of what each technique has to offer, including its specific advantages and disadvantages. Experts in different imaging techniques should collaborate and the different methods should be seen as complementary, not as competitors. Each test must be selected in an integrated and rational way in order to provide clear answers to specific clinical questions and problems, trying to avoid redundant and duplicated information, taking into account its availability, benefits, risks, and cost.

Sudden cardiac death in 2 young siblings

Hypertrophic cardiomyopathy is a disease known for exhibiting phenotypic and genetic heterogeneity. At times, sudden cardiac death may be the first and foremost manifestation of the disease. We report 2 cases of hypertrophic cardiomyopathy causing sudden death, which were diagnosed on autopsy with special emphasis on histopathological findings of this entity. The role of a pathologist cannot be undermined as the disease is a diagnostic challenge often overlooked by the neophytes in the field due to unawareness.

Cardiac transplantation in patients with hypertrophic cardiomyopathy

Cardiac transplantation is a treatment option for patients with hypertrophic cardiomyopathy (HC) who developed refractory heart failure and/or intractable arrhythmia. However, the pretransplant characteristics and post-transplant prognosis for patients with nondilated idiopathic HC has not yet fully elucidated. Therefore, we retrospectively reviewed 813 consecutive transplant recipients undergoing cardiac transplantation at Columbia University Medical Center from 1999 to 2010 and compared the clinical course of 41 patients with idiopathic HC with that of 373 patients with ischemic heart disease and 398 patients with other heart disease. The patients with HC were younger than those with ischemic heart disease (47.8 ± 14.0 vs 57.1 ± 9.4 years; p <0.0001). The proportion of patients undergoing ventricular assist devise surgery for bridge-to-transplant was lower in patients with HC than in those with ischemic heart disease or other heart disease (14.6% vs 31.1% vs 35.7%, all p <0.01). The post-transplant survival of those with HC was better than that for those with ischemic heart disease (90.1% vs 85.8% and 83.9% vs 67.1% at 1 and 5 years, respectively; p = 0.0359), although it was not significantly different from those with other heart disease. Proportional hazards analysis revealed that the subjects with HC had reduced post-transplant mortality (hazard ratio 0.4760, 95% confidential interval 0.1889 to 0.9762; p = 0.042) on univariate, but not multivariate, analysis. Most patients with HC had nondilated left ventricles (left ventricular end-diastolic dimension ≤ 55 mm; n = 27), and post-transplant survival did not differ from that for those with dilated left ventricles (left ventricular end-diastolic dimension >55 mm; n = 14). In conclusion, the post-transplant survival of those with HC did not differ from those of the subjects who underwent transplant for other non-HC indications.

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.

Sudden cardiac death in a 20-year-old male swimmer

In young adults, hypertrophic obstructive cardiomyopathy (HOCM) is an acknowledged risk factor for sudden cardiac death (SCD) in an otherwise healthy and active patient. While the incidence of SCD in young people is not high enough for extensive, wide-scale examinations, the potential for prevention of some deaths via pre-exercise imaging may be beneficial in certain patient populations, such as those with a family history of SCD or professional athletes. We present the case of a healthy 20-year-old man with no past medical history who died while swimming in a river, likely secondary to cardiac arrest in the setting of HOCM.

Right ventricular involvement in hypertrophic cardiomyopathy

The aim of this study was to assess, using cardiovascular magnetic resonance (CMR), whether morphologic right ventricular (RV) abnormalities are present in patients with hypertrophic cardiomyopathy (HC). Left ventricular hypertrophy has been considered the predominant phenotypic expression of HC. Whether structural abnormalities of the right ventricle are also present in HC is unknown. CMR provides complete coverage of both ventricles with high spatial resolution. CMR was applied to study RV morphology in HC. CMR was performed on 46 subjects with HC (mean age 39 +/- 16 years; 70% men) free of pulmonary hypertension and 22 healthy subjects (mean age 44 +/- 16 years; 50% men). Mass, wall thickness, chamber volume, the ejection fraction, and fibrosis were assessed for both ventricles. Maximum RV wall thickness was increased in patients with HC compared with referent controls (7 +/- 2 vs 5 +/- 1 mm, p <0.001), including 15 (33%) with maximum wall thicknesses > or =8 mm (> or =2 SDs higher than the mean for controls) and 4 (9%) with extreme hypertrophy (> or =10 mm). RV hypertrophy was predominantly a diffuse process involving the entire or a significant proportion of the RV wall in most patients (n = 8 [53%]). The RV wall mass index was also increased in patients with HC (28 +/- 9 vs 22 +/- 4 g, p <0.001). A significant correlation was found between maximum RV and left ventricular wall thickness (R(2) = 0.4, p <0.001) and between RV and left ventricular mass (R(2) = 0.4, p <0.001). Only 1 (2%) patient with HC had evidence of RV wall fibrosis. In conclusion, morphologic RV abnormalities are present in a substantial proportion of patients with HC.

Side-to-side linking of myocardial cells in hypertrophic cardiomyopathy: whole heart microscopic observation with tangential sections

By cross-section or longitudinal section, it is difficult to investigate longitudinal features of myocardial cells in the whole heart. Here, introducing the use of tangential sections to obtain longitudinal aspect of myocardial cells in any part of myocardium, the authors evaluated myocardium in the left ventricle in 10 normal hearts and four hearts with hypertrophic cardiomyopathy (HCM). Tangential sections were obtained by peeling the superficial layer of myocardium. After peeling the whole surface, secondary deep layer was peeled. These procedures were repeated more than five times through the wall. Intercalated discs (ICD) were observed immunohistochemically with anti-N-cadherin and antidesmoplakin. In normal hearts, myocardial cells were cut longitudinally and ran parallel in tangential sections. They linked end-to-end with simple and regular ICD with average lengths of 120-130 microm and average sarcomere numbers of 56-65. In HCM hearts, many myocardial cells were cut almost longitudinally running approximately parallel in tangential sections. Myocardial cells frequently showed side-to-side linking characterized by skewed ICD, indistinct ICD counterparts, and longitudinally arranged ICD. Two young HCM hearts had circle-shaped ICD and vacuole-like structures highlighted by immunostaining for N-cadherin, which were actually extracellular structures comparable with irregular side-to-side linking. It is considered that side-to-side linking of myocardial cells is a characteristic microscopic feature in HCM rather than myocardial disarray.

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.

Cardiomyopathy in childhood and adult life, with emphasis on hypertrophic cardiomyopathy

Over 60 entries in the genetic catalog have cardiomyopathy features--32 autosomal dominant, 35 autosomal recessive and X-linked. Over 40 present in, or can have survival into, adult life. Major clinicopathologic categories of these cardiomyopathic disorders included: sudden death (13 entities); cardiac conduction disturbance important feature; associated myopathy or motor dysfunction; storage diseases with cardiac involvement; cardiac amyloidoses; and, other categories. Genes, abnormality of which can cause hypertrophic cardiomyopathy (HCM), have been identified on chromosomes 1, 14 and 15, the locus on chromosome 14 involving the B-myosin heavy chain gene, but at least one unidentified locus is known to exist and there is a suggestive locus on chromosome 16, so that HCM is not a single disease but a group of disorders with clinicopatholopic similarities. To investigate these aspects of HCM in some detail, sixty-six patients with "sharply demarcated" differential myocardial fiber bundle hypertrophy (DMBH), considered to be of significant degree, from a pediatric autopsy data base of approximately 8,000 cases, were reviewed. Twenty-three of the patients died suddenly, without antecedent significant cardiac dysfunction, seven had clinical congestive heart failure of varying duration, three were stillborn, six showed evidence of aspiration of amniotic sac content (three had history of fetal distress), five had ischemic bowel disease, three (two with clinical cerebral palsy and one with Ondine's curse syndrome) had cerebral atrophy and sclerosis and one had extensive more acute encephalomalacia, and a variety of other major "causes of death" were present. Whether all infants and children with DMBH meeting the criteria used, who do not have congenital heart disease, have dominant hypertrophic cardiomyopathy (HCM) cannot be established by studies of this type, but the "concentration" of a gene or genes for HCM in pediatric autopsy series because the strong effect of HCM on life expectancy is relevant to this possibility. The data raise the question that stillbirth, fetal distress with aspiration of amniotic sac content, ischemic bowel disease and cerebral atrophy and sclerosis may be hitherto underappreciated features of HCM in childhood, and that patients with HCM may be peculiarly liable to die with certain types of septic shock, such as acute meningococcemia. In the material of this study, sudden death was statistically more frequent in females than in males in childhood (p < .029).

Pulmonary veno-occlusive disease associated with hypertrophic cardiomyopathy

An autopsy analysis of the lung findings in 14 cases of hypertrophic cardiomyopathy (HCM) was undertaken, with particular attention paid to the pulmonary vessels. Six of the 14 cases of HCM showed histological features of pulmonary veno-occlusive disease (PVOD). The coexistence of these two rare conditions appears to be more than a chance association. In view of recent advances in the understanding of the genetic basis for HCM, genetic analysis of patients with PVOD should be performed in order to determine whether there may be a common genetic context for the coexistence of these disorders.

Endomyocardial biopsy: a review of the literature

A review of the literature relating to endomyocardial biopsy (EMB) is presented. This is considered important at this time since EMB is being utilized with increasing frequency, particularly for the diagnosis of myocarditis. The development of the technique is briefly outlined. Emphasis is placed on the clinical application of EMB in the various primary cardiomyopathies (dilated, hypertrophic, restrictive, and obliterative), the infiltrative secondary cardiomyopathies (amyloidosis, sarcoidosis, hemochromatosis), myocarditis, as well as such conditions as adriamycin cardiotoxicity, cardiac transplant rejection, and Kawasaki disease. More controversial application of EMB in primary mitral valve prolapse (Barlow's syndrome), idiopathic ventricular arrhythmias, and the elucidation of the enigmatic finding of angina with angiographically normal coronary arteries is detailed. Experience with immunological and biochemical investigation of biopsy material, as well as with virus isolation and drug assays in the myocardium, is alluded to. Complications encountered with this procedure are also discussed, and its future role is contemplated.