Imaging Phenotype Versus Genotype in Hypertrophic Cardiomyopathy

Measurements of the Interventricular Septum and Mitral Leaflet Length in Hypertrophic Cardiomyopathy Patients Who Underwent Surgical Myectomy: A Prospective Comparative Multimodality Imaging Study

Transesophageal echocardiography (TEE) plays an important role for real-time procedural guidance during surgical smyectomy (SM) for hypertrophic obstructive cardiomyopathy (HOCM). We aimed to compare (1) interventricular septum (IVS) thickness using 2- (2D) and 3-dimensional (3D) intraoperative TEE and preoperative cardiac magnetic resonance (CMR) and (2) mitral valve (MV) leaflet length using 2D, 3D TEE, automatic quantification of mitral valve (AMVQ) and preoperative CMR. We prospectively studied 50 patients with HOCM (age 59 ± 12 years, 44% men) who underwent SM during 2018 to 2019. The maximal basal, mid, and distal anteroseptum (AS) and inferoseptum (IS) were measured by multiplanar 3D reconstruction on TEE and by short-axis imaging on preoperative CMR and classified as mild (≤18 mm), moderate (18 to 25 mm), or severe (≥25 mm) groups based on AS and IS thickness on CMR. MV leaflet lengths were evaluated by preoperative CMR and intraprocedural 2D TEE, zoom 3D TEE, and AMVQ (EchoPAC, General Electric, Wisconsin). There was a moderate correlation between AS and IS thickness on 3D TEE and CMR (R2 = 0.46, p <0.01 and R2 = 0.41, p <0.01, respectively), with 3D TEE showing an average overestimation of 3.8 and 4.7 mm versus CMR. The 3D TEE overestimated 14 patients (56%) with mild thickness as moderate and 5 patients (22%) with moderate thickness as severe. Assuming 3D TEE as the gold standard, the closest correlation for anterior mitral leaflet length was with CMR (average overestimation by CMR of 0.5 mm [root mean square deviation (RMSE%) 17]), intermediate correlation with 2D TEE (average deviation of 0.6 mm [RMSE% 21]) and no correlation with AMVQ (average deviation of 0.7 mm [RMSE% 24]). In conclusion, 3D TEE overestimates IVS thickness versus CMR in patients with HOCM who underwent SM, with greater discrepancy in those with thinner IVS. There are significant differences in MV lengths measured using different imaging techniques.

2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy.

METHODS

A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy.

METHODS

A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This executive summary of the hypertrophic cardiomyopathy clinical practice guideline provides recommendations and algorithms for clinicians to diagnose and manage hypertrophic cardiomyopathy in adult and pediatric patients as well as supporting documentation to encourage their use.

METHODS

A comprehensive literature search was conducted from January 1, 2010, to April 30, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases.

STRUCTURE

Many recommendations from the earlier hypertrophic cardiomyopathy guidelines have been updated with new evidence or a better understanding of earlier evidence. This summary operationalizes the recommendations from the full guideline and presents a combination of diagnostic work-up, genetic and family screening, risk stratification approaches, lifestyle modifications, surgical and catheter interventions, and medications that constitute components of guideline directed medical therapy. For both guideline-directed medical therapy and other recommended drug treatment regimens, the reader is advised to follow dosing, contraindications and drug-drug interactions based on product insert materials.

2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

Aim This executive summary of the hypertrophic cardiomyopathy clinical practice guideline provides recommendations and algorithms for clinicians to diagnose and manage hypertrophic cardiomyopathy in adult and pediatric patients as well as supporting documentation to encourage their use. Methods A comprehensive literature search was conducted from January 1, 2010, to April 30, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Structure Many recommendations from the earlier hypertrophic cardiomyopathy guidelines have been updated with new evidence or a better understanding of earlier evidence. This summary operationalizes the recommendations from the full guideline and presents a combination of diagnostic work-up, genetic and family screening, risk stratification approaches, lifestyle modifications, surgical and catheter interventions, and medications that constitute components of guideline directed medical therapy. For both guideline-directed medical therapy and other recommended drug treatment regimens, the reader is advised to follow dosing, contraindications and drug-drug interactions based on product insert materials.

Cancer genotypes prediction and associations analysis from imaging phenotypes: a survey on radiogenomics

In this paper, we present a survey on the progress of radiogenomics research, which predicts cancer genotypes from imaging phenotypes and investigates the associations between them. First, we present an overview of the popular technology modalities for obtaining diagnostic medical images. Second, we summarize recently used methodologies for radiogenomics analysis, including statistical analysis, radiomics and deep learning. And then, we give a survey on the recent research based on several types of cancers. Finally, we discuss these studies and propose possible future research directions. In conclusion, we have identified strong correlations between cancer genotypes and imaging phenotypes. In addition, with the rapid growth of medical data, deep learning models show great application potential for radiogenomics.

Explainable Anatomical Shape Analysis Through Deep Hierarchical Generative Models

Quantification of anatomical shape changes currently relies on scalar global indexes which are largely insensitive to regional or asymmetric modifications. Accurate assessment of pathology-driven anatomical remodeling is a crucial step for the diagnosis and treatment of many conditions. Deep learning approaches have recently achieved wide success in the analysis of medical images, but they lack interpretability in the feature extraction and decision processes. In this work, we propose a new interpretable deep learning model for shape analysis. In particular, we exploit deep generative networks to model a population of anatomical segmentations through a hierarchy of conditional latent variables. At the highest level of this hierarchy, a two-dimensional latent space is simultaneously optimised to discriminate distinct clinical conditions, enabling the direct visualisation of the classification space. Moreover, the anatomical variability encoded by this discriminative latent space can be visualised in the segmentation space thanks to the generative properties of the model, making the classification task transparent. This approach yielded high accuracy in the categorisation of healthy and remodelled left ventricles when tested on unseen segmentations from our own multi-centre dataset as well as in an external validation set, and on hippocampi from healthy controls and patients with Alzheimer's disease when tested on ADNI data. More importantly, it enabled the visualisation in three-dimensions of both global and regional anatomical features which better discriminate between the conditions under exam. The proposed approach scales effectively to large populations, facilitating high-throughput analysis of normal anatomy and pathology in large-scale studies of volumetric imaging.

Cardiovascular Magnetic Resonance Imaging of Inherited Heart Conditions

Imaging modalities are central to diagnosis and prognostication of confirmed or suspected inherited cardiomyopathies. The availability and use of cardiovascular magnetic resonance imaging (CMR) to supplement traditional modalities has increased substantially and has several advantages over traditional imaging techniques. CMR is unique in its ability to easily acquire images in any plane. Moreover, advances in CMR sequences have begun to enable characterisation of the myocardium without the need for invasive biopsy and has provided a major step forward in the understanding of inherited heart disease pathology and genotype-phenotype interactions. This review summarises the current role of CMR in inherited cardiomyopathies depending on their genotype and phenotype status, using arrhythmogenic right ventricular dysplasia/cardiomyopathy and hypertrophic cardiomyopathy as prototypical examples.

Magnetic resonance imaging of the papillary muscles of the left ventricle: normal anatomy, variants, and abnormalities

Left ventricular papillary muscles are small myocardial structures that play an important role in the functioning of mitral valve and left ventricle. Typically, there are two groups of papillary muscles, namely the anterolateral and the posteromedial groups. Cardiovascular magnetic resonance (CMR) is a valuable imaging modality in the evaluation of papillary muscles, providing both morphological and functional information. There is a remarkably wide variation in the morphology of papillary muscles. These variations can be asymptomatic or associated with symptoms related to LV outflow tract obstruction, often associated with hypertrophic cardiomyopathy. Abnormalities of the papillary muscles range from congenital disorders to neoplasms. Parachute mitral valve is the most common congenital abnormality of papillary muscles, in which all the chordae insert into a single papillary muscle. Papillary muscles can become dysfunctional, most commonly due to ischemia. Papillary muscle rupture is a major complication of acute myocardial infarction that results in mitral regurgitation and associated with high mortality rates. The most common papillary neoplasm is metastasis, but primary benign and malignant neoplasms can also be seen. In this article, we discuss the role of CMR in the evaluation of papillary muscle anatomy, function, and abnormalities.

Disparities in the Diagnosis of Hypertrophic Obstructive Cardiomyopathy: A Narrative Review of Current Literature

Hypertrophic obstructive cardiomyopathy (HOCM) is a disorder of abnormal thickening of the myocardium that affects 0.2% of the population. HOCM is a frequently implicated cause of sudden cardiac death (SCD) in young athletes. In this manner, this condition has the capacity for tremendous emotional, social, financial, and medical burdens for families and communities across the country. Multiple factors including genetics and hormonal elements are believed to play a role in the development of this cardiomyopathy. HOCM is an autosomal dominant trait with variable expressivity. It is associated with several genetic changes in the myosin heavy chain genes. Current treatment includes optimization of cardiac risk factors and medical management with beta-adrenergic blockade with definitive treatment of surgical intervention to reduce cardiac workload. The demographic most likely to be diagnosed with HOCM based upon clinical registry data is Caucasian boys and men. However, a growing body of data supports increased prevalence in African American populations and percentages equal to, if not higher than, Caucasian males in Hispanic populations. Similarly, males of African American ethnicity that participate in basketball are the most likely demographic to be affected by HOCM based on the data available from the National Collegiate Athletic Association (NCAA). Further, though rates of diagnosis may be up to 1.5 times higher in males than in females, an increasing number of studies demonstrate an increased prevalence of HOCM in females, often presenting with worse symptoms and an increased incidence of disease progression. Similarly, data suggest that age of diagnosis is associated with various prognostic factors including annual mortality. In addition, consideration of the social determinants of health undoubtedly impacts the rate of diagnosis, access to care, and HOCM-related complications in underserved populations. Effective screening including auscultation and electrocardiography (EKG) with confirmatory echocardiography in these communities supports equitable surveillance and management of HOCM.

Atrial Fibrillation and Anticoagulation in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) represents a common inherited cardiac disorder with well-known complications Including stroke and sudden cardiac death. There is a recognised association between HCM and the development of AF. This review describes the epidemiology of AF within the HCM population and analyses the risk factors for the development of AF. It further discusses the outcomes associated with AF in this population, including the evidence in support of higher stroke risk in patients with HCM with AF compared with the general AF population. Finally, the evidence and recommendations for anticoagulation in this patient group are addressed.

Hypertrophic Cardiomyopathy from A to Z: Genetics, Pathophysiology, Imaging, and Management

Hypertrophic cardiomyopathy (HCM) is a heterogeneous group of diseases related to sarcomere gene mutations exhibiting heterogeneous phenotypes with an autosomal dominant mendelian pattern of inheritance. The disorder is characterized by diverse phenotypic expressions and variable natural progression, which may range from dyspnea and/or syncope to sudden cardiac death. It is found across all racial groups and is associated with left ventricular hypertrophy in the absence of another systemic or cardiac disease. The management of HCM is based on a thorough understanding of the underlying morphology, pathophysiology, and clinical course. Imaging findings of HCM mirror the variable expressivity and penetrance heterogeneity, with the added advantage of diagnosis even in cases where a specific mutation may not yet be found. The diagnostic information obtained from imaging varies depending on the specific stage of HCM-phenotype manifestation, including the prehypertrophic, hypertrophic, and later stages of adverse remodeling into the burned-out phase of overt heart failure. However, subtle or obvious, these imaging findings become critical components in diagnosis, management, and follow-up of HCM patients. Although diagnosis of HCM traditionally relies on clinical assessment and transthoracic echocardiography, recent studies have demonstrated increased utility of multidetector computed tomography (CT) and particularly cardiac magnetic resonance (MR) imaging in diagnosis, phenotype differentiation, therapeutic planning, and prognostication. In this article, we provide an overview of the genetics, pathophysiology, and clinical manifestations of HCM, with the spectrum of imaging findings at MR imaging and CT and their contribution in diagnosis, risk stratification, and therapy.

Distribution and Clinical Significance of High Signal Intensity of the Myocardium on T2-Weighted Images in 2 Phenotypes of Hypertrophic Cardiomyopathy

OBJECTIVE

The aim of this study was to evaluate distribution and clinical significance of high signal intensity of the myocardium on T2-weighted images (T2-HI) in 2 phenotypes of hypertrophic cardiomyopathy (HCM).

METHODS

Thirty-six patients with asymmetrical septal HCM (ASH) and 18 patients with apical HCM (APH) and their 864 myocardial segments were investigated. The distribution of T2-HI was compared with that of late gadolinium enhancement (LGE), and the relationships between T2-HI and clinical risk markers were evaluated. T2 values of the T2-HI were estimated with T2 mapping.

RESULTS

The T2-HI was observed in 18 segments (3.1%) in 13 patients with ASH (36.1%) and in 12 segments (4.2%) in 8 patients with APH (44.4%). It was often localized outside LGE. The presence of T2-HI was related to syncope in ASH (P = 0.016). Furthermore, it had higher T2 values (61.1 milliseconds) than the reference myocardium (47.3 milliseconds).

CONCLUSIONS

High signal intensity of the myocardium on T2-weighted images often locates outside LGE and reflects myocardial damage, which is related to syncope in ASH.

Cardiovascular magnetic resonance findings in patients with PRKAG2 gene mutations

BACKGROUND

Autosomal dominantly inherited PRKAG2 cardiac syndrome is due to a unique defect of the cardiac cell metabolism and has a distinctive histopathology with excess intracellular glycogen, and prognosis different from sarcomeric hypertrophic cardiomyopathy. We aimed to define the distinct characteristics of PRKAG2 using cardiovascular magnetic resonance (CMR).

METHODS

CMR (1.5 T) and genetic testing were performed in two families harboring PRKAG2 mutations. On CMR, segmental analysis of left ventricular (LV) hypertrophy (LVH), function, native T1 mapping, and late gadolinium enhancement (LGE) were performed.

RESULTS

Six individuals (median age 23 years, range 16-48; two females) had a PRKAG2 mutation: five with an R302Q mutation (family 1), and one with a novel H344P mutation (family 2). Three of six mutation carriers had LV mass above age and gender limits (203 g/m2, 157 g/m2 and 68 g/m2) and others (with R302Q mutation) normal LV masses. All mutation carriers had LVH in at least one segment, with the median maximal wall thickness of 13 mm (range 11-37 mm). Two R302Q mutation carriers with markedly increased LV mass (203 g/m2 and 157 g/m2) showed a diffuse pattern of hypertrophy but predominantly in the interventricular septum, while other mutation carriers exhibited a non-symmetric mid-infero-lateral pattern of hypertrophy. In family 1, the mutation negative male had a mean T1 value of 963 ms, three males with the R302Q mutation, LVH and no LGE a mean value of 918 ± 11 ms, and the oldest male with the R302Q mutation, extensive hypertrophy and LGE a mean value of 973 ms. Of six mutations carriers, two with advanced disease had LGE with 11 and 22 % enhancement of total LV volume.

CONCLUSIONS

PRKAG2 cardiac syndrome may present with eccentric distribution of LVH, involving focal mid-infero-lateral pattern in the early disease stage, and more diffuse pattern but focusing on interventricular septum in advanced cases. In patients at earlier stages of disease, without LGE, T1 values may be reduced, while in the advanced disease stage T1 mapping may result in higher values caused by fibrosis. CMR is a valuable tool in detecting diffuse and focal myocardial abnormalities in PRKAG2 cardiomyopathy.

Left Ventricular Outflow Tract Obstruction in Hypertrophic Cardiomyopathy Patients Without Severe Septal Hypertrophy

Background—

In patients with hypertrophic cardiomyopathy and left ventricular outflow tract (LVOT) obstruction, but without basal septal hypertrophy, we sought to identify mitral valve (MV) and papillary muscle (PM) abnormalities that predisposed to LVOT obstruction, using echo and cardiac magnetic resonance.

Methods and Results—

We studied 121 patients with hypertrophic cardiomyopathy hypertrophic cardiomyopathy (age, 49±17 years; 60% men; 57% on β-blockers) with a basal septal thickness of ≤1.8 cm who underwent echocardiography (rest+stress) and cine cardiac magnetic resonance. Echo measurements included maximal LVOT gradient (rest/provocable), MV leaflet length (parasternal long, 4 and 3-chamber views), and abnormal chordal attachment to mid/base of anterior MV. Cine cardiac magnetic resonance measurements included basal septal thickness, number/area of PM heads, and bifid PM mobility (in systole and diastole). Mean basal septal thickness, LVOT gradient, and LV ejection fraction were 1.5±0.3 cm, 72±54 mm Hg, and 61±6%, respectively. The number of anterolateral and posteromedial PM heads was 2.7±0.7 and 2.6±0.7, respectively. Anterolateral and posteromedial PM areas were 19.9±7 cm 2 and 17.1±6 cm 2 , respectively. PM mobility was 11±6°. On multivariable analysis, predictors of maximal LVOT gradient were basal septal thickness, bifid PM mobility, anterior mitral leaflet length, and abnormal chordal attachment to base of anterior mitral leaflet. Forty-five patients underwent surgery to relieve LVOT obstruction, of which 52% needed an additional nonmyectomy (MV repair/replacement or PM reorientation) approach.

Conclusions—

In hypertrophic cardiomyopathy patients without significant LV hypertrophy, in addition to basal septal thickness, anterior MV length, abnormal chordal attachment, and bifid PM mobility are associated with LVOT obstruction. In such patients, additional procedures on MV and PM (±myectomy) could be considered.

Magnetic Resonance Imaging of Hypertrophic Cardiomyopathy: Beyond Left Ventricular Wall Thickness

During the past decade, cardiac magnetic resonance has gained increasing popularity in the diagnosis of hypertrophic cardiomyopathy because of its greater accuracy and better characterization of cardiac morphology compared with other imaging modalities. In this pictorial essay, a global clinical portrait of hypertrophic cardiomyopathy will be drawn. The various radiologic findings associated with each variant of hypertrophic cardiomyopathy, and the clinical edge offered by cardiac magnetic resonance will be discussed.

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.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant, cardiovascular disorder that carries the risk of sudden cardiac death. The prevalence of HCM is 1:500 persons. The purpose of this article is to provide an overview of the pathophysiology, symptoms, complications, diagnostic testing, and treatment. The silent presentation of HCM presents unique diagnostic challenges and complicates prompt identification. Diagnostic testing and management strategies for the care of a person with HCM are discussed. HCM has individualized presentation and therefore requires individualized therapy.

Use of a highly-sensitive cardiac troponin I assay in a screening population for hypertrophic cardiomyopathy: a case-referent study

Background

Hypertrophic cardiomyopathy (HCM) is a genetic condition, and relatives of affected persons may be at risk. Cardiac troponin biomarkers have previously been shown to be elevated in HCM. This study examines the new highly-sensitive cardiac troponin I (hsTnI) assay in a HCM screening population.

Methods

Nested case–control study of consecutive HCM sufferers and their relatives recruited from May 2010 to September 2011. After informed consent, participants provided venous blood samples and clinical and echocardiographic features were recorded. Associations between the natural log (ln) of the contemporary troponin I (cTnI) and hsTnI assays and markers of cardiac hypertrophy were examined. Multiple regression models were fitted to examine the predictive ability of hsTnI for borderline or definite HCM.

Results

Of 107 patients, 24 had borderline and 19 had definite changes of HCM. Both TnI assays showed significant, positive correlations with measures of cardiac muscle mass. After age and sex adjustment, the area under the receiver operator characteristic (AUROC) curve for the outcome of HCM was 0.78, 95% CI [0.65, 0.90], for ln(hsTnI), and 0.66, 95% CI [0.51, 0.82], for ln(cTnI) (p=0.11). Including the hsTnI assay in a multiple-adjusted “screening” model for HCM resulted in a non-significant improvement in both the AUROC and integrated discrimination index.

Conclusions

Both cTnI and hsTnI show a graded, positive association with measures of cardiac muscle mass in persons at risk of HCM. Further studies will be required to evaluate the utility of these assays in ECG- and symptom-based identification of HCM in at-risk families.

Genetic Cardiomyopathies Causing Heart Failure

Despite the striking advances in medical and surgical therapy, the morbidity, mortality, and economic burden of heart failure (HF) remain unacceptably high. There is increasing evidence that the risk and course of HF depend on genetic predisposition; however, the genetic contribution to HF is heterogeneous and complex. At one end of the spectrum are the familial monogenic HF syndromes in which causative mutations are rare but highly penetrant. At the other, HF susceptibility and course may be influenced by more common, less penetrant genetic variants. As detailed in this review, efforts to unravel the basis of the familial cardiomyopathies at the mendelian end of the spectrum already have begun to deliver on the promise of informative mechanisms, novel gene-based diagnostics, and therapies for distinct subtypes of HF. However, continued progress requires the differentiation of pathogenic mutations, disease modifiers, and rare, benign variants in the deluge of data emerging from increasingly accessible novel sequencing technologies. This represents a significant challenge and demands a sustained effort in analysis of extended family pedigrees, diligent clinical phenotyping, and systematic annotation of human genetic variation.

Contrast-enhanced cardiac magnetic resonance imaging

Cardiac magnetic resonance (CMR) imaging has significantly evolved in the past decade and is well established in the evaluation of coronary artery disease (CAD). The evaluation of cardiac anatomy and contractility by high-resolution CMR can be improved by using intravenous administration of gadolinium-based contrast agents. Delayed enhancement CMR imaging has become the gold standard for quantification of myocardial viability in CAD. Contrast-enhanced CMR imaging may circumvent the need for endomyocardial biopsy or localize the involved regions, thereby improving the diagnostic yield of this invasive procedure. The application of contrast-enhanced CMR as an advanced imaging technique for ischemic and nonischemic diseases is reviewed.

Role of cardiac magnetic resonance imaging in assessing ischemic and nonischemic cardiomyopathies

One of the diagnostic challenges in cardiology is the assessment of patients with suspected cardiomyopathies. The traditional approach involves clinical history and examination, followed by echocardiography and invasive angiography. Advances in cardiac MRI enable cardiologists to comprehensively assess both ischemic and nonischemic cardiomyopathies, providing information regarding cardiac anatomy, myocardial and valve functions, as well as tissue characterization.

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.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is a fascinating disease of marked heterogeneity. Hypertrophic cardiomyopathy was originally characterized by massive myocardial hypertrophy in the absence of known etiology, a dynamic left ventricular outflow obstruction, and increased risk of sudden death. It is now well accepted that multiple mutations in genes encoding for the cardiac sarcomere are responsible for the disease. Complex morphologic and pathophysiologic differences, disparate natural history studies, and novel treatment strategies underscore the challenge to the practicing cardiologist when faced with the management of the hypertrophic cardiomyopathy patient.