The Remarkable 50 Years of Imaging in HCM and How it Has Changed Diagnosis and Management: From M-Mode Echocardiography to CMR

Obstruction in Hypertrophic Cardiomyopathy: Many Faces

Hypertrophic cardiomyopathy (HCM), the most common inherited cardiomyopathy, exhibits left ventricular hypertrophy not secondary to other causes, with varied phenotypic expression. Enhanced actin-myosin interaction underlies excessive myocardial contraction, frequently resulting in dynamic obstruction within the left ventricle. Left ventricular outflow tract obstruction, occurring at rest or with provocation in 75% of HCM patients, portends adverse prognosis, contributes to symptoms, and is frequently a therapeutic target. Transthoracic echocardiography plays a crucial role in the screening, initial diagnosis, management, and risk stratification of HCM. Herein, we explore echocardiographic evaluation of HCM, emphasizing Doppler assessment for obstruction. Echocardiography informs management strategies through noninvasive hemodynamic assessment, which is frequently obtained with various provocative maneuvers. Recognition of obstructive HCM phenotypes and associated anatomical abnormalities guides therapeutic decision-making. Doppler echocardiography allows monitoring of therapeutic responses, whether it be medical therapies (including cardiac myosin inhibitor therapy) or septal reduction therapies, including surgical myectomy and alcohol septal ablation. This article discusses the hemodynamics of obstruction and practical application of Doppler assessment in HCM. In addition, it provides a visual atlas of obstruction in HCM, including high-quality figures and complementary videos that illustrate the many facets of dynamic obstruction.

Role of Imaging in the Diagnosis, Evaluation, and Management of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is increasingly recognized and may benefit from the recent approval of new, targeted medical therapy. Successful management of HCM is dependent on early and accurate diagnosis. The lack of a definitive diagnostic test, the wide variation in phenotype and the commonness of phenocopy conditions, and the presence of normal or hyperdynamic left ventricular function in most patients makes HCM a condition that is highly dependent on imaging for all aspects of management including, diagnosis, classification, predicting risk of complications, detecting complications, identifying risk for ventricular arrhythmias, evaluating choice of therapy and monitoring therapy, intraprocedural guidance, and screening family members. Although echocardiographic imaging remains the mainstay in the diagnosis and subsequent management of HCM, this disease clearly requires multimethod imaging for various aspects of optimal patient care. Advances in echocardiography hardware and techniques, development and refinement of imaging with computed tomography, magnetic resonance, and nuclear scanning, and the emergence of very focused assessments such as diastology and fibrosis imaging have all advanced the diagnosis and management of HCM. In this review, we discuss the relative utility and evidence support for these imaging approaches to contribute to improve patient outcomes.

Patient-specific computational fluid dynamics for hypertrophic obstructive cardiomyopathy

BACKGROUND

The heterogeneous morphologic and functional expression of hypertrophic obstructive cardiomyopathy (HOCM) is evidenced by established imaging, multimodality imaging is essential for a comprehensive assessment but may remain uncertain. This study aimed to develop a patient-specific hemodynamics assessment with cardiac computed tomography angiography (CCTA) based computational fluid dynamics (CFD) and prove its usability in cohorts of HOCM patients.

METHODS

A retrospective study was performed on eight HOCM patients with septal myectomy who had both preoperative and postoperative CCTA as well as transthoracic echocardiography (TTE). The three-dimensional models were reconstructed from CCTA data, following which patient-specific CFD simulations were performed to estimate the blood velocity, pressure gradient, and wall shear stress. The simulation output was compared with TTE. Based on CFD simulations, retrospective and blinded virtual myectomy was also performed, to predict the minimum resected volume for improving obstruction in patients.

RESULT

The complex HOCM anatomy was successfully reconstructed for all 8 patients. The CFD simulation accurately assessed the pressure gradient, flow velocity. There was a good correlation between the peak pressure gradient measured by CFD and TTE in the pre- and post-operative assessments (r = 0.87 and 0.84, respectively), and the flow velocity (r = 0.87 and 0.90, respectively). The volumes of minimal resection myocardium predicted by CFD and virtual myectomy were consistent with the actual resection volumes.

CONCLUSION

CCTA-based CFD for HOCM patients may play a unique role in the assessment of patient-specific morphology and hemodynamics. Combination with virtual myectomy might allow for optimizing therapy planning in septal myectomy.

CLINICAL PERSPECTIVE

CFD based CCTA may emerge as a complement to established imaging strategies, with accurate three-dimensional reconstruction and hemodynamic simulation of the left ventricle in this retrospective study. Combined with virtual myectomy, CFD simulation might allow for predicting the volume of resected myocardium for septal myectomy. Moving forward, this technology may be used by clinicians to better assess the conditions of HOCM patients, and guide the extent and depth of resection during septal myectomy. Therefore, further prospective clinical evaluation is clearly warranted.

Detection of haemodynamic obstruction in hypertrophic cardiomyopathy using the sub-aortic complex: a cardiac MRI and Doppler study

AIM

To investigate the "sub-aortic complex (SAC)", a new cardiac magnetic resonance imaging (CMRI)-derived parameter, for the evaluation of left ventricular (LV) outflow tract (LVOT) obstruction in patients with hypertrophic cardiomyopathy (HCM), compared with conventional CMRI parameters and Doppler echocardiography.

MATERIALS AND METHODS

A total of 157 consecutive patients with HCM were recruited retrospectively. The patients were divided into two groups, 87 with LVOT obstruction and 70 without obstruction. The SAC was defined as a specific anatomical SAC affecting the LVOT, which were measured on the LV three-chamber steady-state free precession (SSFP) cine image at the end-systolic phase. The relations between the existence and severity of obstruction and SAC index (SACi) were evaluated using Pearson's correlation coefficient, receiver operating characteristic (ROC) curves, and logistic regression.

RESULTS

The SACs were significantly different between the obstructive and non-obstructive groups. The ROC curves indicated that the SACi was able to discriminate obstructive and non-obstructive patients with the best predictive accuracy (AUC = 0.949, p<0.001). The SACi was an independent predictor of LVOT obstruction and there was a significant negative correlation between resting LVOT pressure gradient and SACi (r=0.72 p<0.001). In the subgroup of patients with or without severe basal septal hypertrophy, the SACi was still able to predict LVOT obstruction with excellent diagnostic accuracy (AUC = 0.944 and 0.948, p<0.001, respectively).

CONCLUSION

The SAC is a reliable and straightforward CMRI marker for assessing LVOT obstruction. It is more effective than CMRI two-dimensional flow in diagnosing the severity of obstruction in patients with HCM.

Emerging epigenetic therapies of cardiac fibrosis and remodelling in heart failure: from basic mechanisms to early clinical development

Cardiovascular diseases and specifically heart failure (HF) impact global health and impose a significant economic burden on society. Despite current advances in standard of care, the risks for death and readmission of HF patients remain unacceptably high and new therapeutic strategies to limit HF progression are highly sought. In disease settings, persistent mechanical or neurohormonal stress to the myocardium triggers maladaptive cardiac remodelling, which alters cardiac function and structure at both the molecular and cellular levels. The progression and magnitude of maladaptive cardiac remodelling ultimately leads to the development of HF. Classical therapies for HF are largely protein-based and mostly are targeted to ameliorate the dysregulation of neuroendocrine pathways and halt adverse remodelling. More recently, investigation of novel molecular targets and the application of cellular therapies, epigenetic modifications, and regulatory RNAs has uncovered promising new avenues to address HF. In this review, we summarize the current knowledge on novel cellular and epigenetic therapies and focus on two non-coding RNA-based strategies that reached the phase of early clinical development to counteract cardiac remodelling and HF. The current status of the development of translating those novel therapies to clinical practice, limitations, and future perspectives are additionally discussed.

Effective treatment of hypertrophic cardiomyopathy with left ventricular outflow tract obstruction using a covered stent

A woman in her 60s presented with progressive exertional dyspnoea, exertional chest pressure and exertional dizziness. Echocardiogram identified a 156 mm Hg left ventricular outflow tract gradient with provocation, indicating hypertrophic cardiomyopathy with left ventricular outflow obstruction-confirmed with MRI and angiogram. An alcohol septal ablation was planned but due to communication of the second septal perforator with the right ventricle and a wire-induced mid-left anterior descending artery dissection, alcohol septal ablation was not performed. Instead, a covered stent was placed in the mid-left anterior descending artery covering the origins of the third and fourth septal perforators. The left ventricular outflow tract gradient decreased from 90 to 30 mm Hg with provocation and her symptoms improved. Follow-up showed a left ventricular outflow tract gradient of 35 mm Hg with provocation and decreased symptoms.

The Initial Experience of Left Bundle Branch Area Pacing in Patients with Hypertrophic Cardiomyopathy

PURPOSE

Whether Left bundle branch area pacing (LBBAP) could be achieved in patients with hypertrophic cardiomyopathy (HCM) requiring ventricular pacing remains unknown. The present study aimed to investigate the feasibility and effect of LBBAP in HCM.

METHODS

Patients with HCM who underwent LBBAP were recruited from November 2018 to September 2021. Clinical characteristics, echocardiographic, and pacing parameters were prospectively collected at baseline and during follow-up.

RESULTS

Eleven consecutive HCM patients who attempted LBBAP were included (mean age 64.0±8.7 years, female 45.5%, mean interventricular septum 16.7mm). The success rate of LBBAP was 36.4% (4/11) and the reason for failed LBBAP in other 7 HCM patients was the inability to screw the lead into the deep septum or capture the left bundle branch. Patients with successful LBBAP had significantly narrower QRS duration than those with failed (118.0 ± 3.7 ms vs. 140.9 ± 9.4 ms, p = 0.01) while the capture thresholds, sensing amplitudes, and pacing impedances were similar. Successful cases presented with less positive late gadolinium enhancement (25.0% vs. 71.4%, p = 0.02) and thinner interventricular thickness (14.5 ± 1.0 mm vs. 18.0 ± 2.5 mm, p = 0.02) when compared with failed cases. Pacing parameters remained stable and no procedure-related complications occurred during a mean follow-up of 8.9 ± 7.3 months.

CONCLUSION

LBBAP may be successfully achieved in less than half of HCM patients due to thick interventricular septum and heavy burden of myocardial fibrosis. Pacing strategies should be cautiously considered in patients with HCM. This article is protected by copyright. All rights reserved.

Assessment of Exercise Function in Children and Young Adults with Hypertrophic Cardiomyopathy and Correlation with Transthoracic Echocardiographic Parameters

Exercise function is well characterized in adults with hypertrophic cardiomyopathy (HCM); however, there is a paucity of data in children and young adults with HCM. Here we sought to characterize exercise function in young people with HCM, understand limitations in exercise function by correlating exercise function parameters with echocardiogram parameters and identify prognostic value of exercise parameters. We performed a retrospective, single-center cohort study characterizing exercise function in patients < 26 years old with HCM undergoing cardiopulmonary exercise testing (CPET). Patients with syndromic HCM or submaximal effort were excluded. We compared exercise function in this cohort to population normal values and measured changes in exercise function over time. We correlated exercise function parameters with echocardiographic parameters and investigated the relationship between exercise test parameters and a clinical composite outcome comprised of significant ventricular arrhythmia, death, or heart transplantation. We identified 229 CPETs performed by 117 patients (mean age at time of first CPET 15.6 ± 3.2 years). Mean %-predicted peak VO2, O2 pulse, and peak heart rate were statistically significantly depressed compared to population normal values and exercise function gradually worsened over time. Abnormal exercise testing correlated closely with echocardiographic indices of diastolic dysfunction. There was a trend toward increased incidence of poor clinical outcome in patients with abnormal exercise function. While adverse clinical outcomes were rare, normal exercise function appears to be a marker of low risk for adverse clinical outcomes in this population.

Cardiac MR: From Theory to Practice

Cardiovascular disease (CVD) is the leading single cause of morbidity and mortality, causing over 17. 9 million deaths worldwide per year with associated costs of over $800 billion. Improving prevention, diagnosis, and treatment of CVD is therefore a global priority. Cardiovascular magnetic resonance (CMR) has emerged as a clinically important technique for the assessment of cardiovascular anatomy, function, perfusion, and viability. However, diversity and complexity of imaging, reconstruction and analysis methods pose some limitations to the widespread use of CMR. Especially in view of recent developments in the field of machine learning that provide novel solutions to address existing problems, it is necessary to bridge the gap between the clinical and scientific communities. This review covers five essential aspects of CMR to provide a comprehensive overview ranging from CVDs to CMR pulse sequence design, acquisition protocols, motion handling, image reconstruction and quantitative analysis of the obtained data. (1) The basic MR physics of CMR is introduced. Basic pulse sequence building blocks that are commonly used in CMR imaging are presented. Sequences containing these building blocks are formed for parametric mapping and functional imaging techniques. Commonly perceived artifacts and potential countermeasures are discussed for these methods. (2) CMR methods for identifying CVDs are illustrated. Basic anatomy and functional processes are described to understand the cardiac pathologies and how they can be captured by CMR imaging. (3) The planning and conduct of a complete CMR exam which is targeted for the respective pathology is shown. Building blocks are illustrated to create an efficient and patient-centered workflow. Further strategies to cope with challenging patients are discussed. (4) Imaging acceleration and reconstruction techniques are presented that enable acquisition of spatial, temporal, and parametric dynamics of the cardiac cycle. The handling of respiratory and cardiac motion strategies as well as their integration into the reconstruction processes is showcased. (5) Recent advances on deep learning-based reconstructions for this purpose are summarized. Furthermore, an overview of novel deep learning image segmentation and analysis methods is provided with a focus on automatic, fast and reliable extraction of biomarkers and parameters of clinical relevance.

Cardiovascular Diseases That Have Emerged From the Darkness

It is important for both the patient and physician communities to have timely access to information recognizing rapid progress in the diagnosis and treatment of familiar but relatively uncommon cardiovascular diseases. Patients with 3 cardiovascular diseases (ie, hypertrophic cardiomyopathy, pulmonary arterial hypertension, and transthyretin (TTR) cardiac amyloidosis (ATTR)]), once considered rare without effective management options and associated with malignant prognosis, have now benefited substantially from the development of a variety of innovative therapeutic strategies. In addition, in each case, enhanced diagnostic testing has expanded the patient population and allowed for more widespread administration of contemporary treatments. In hypertrophic cardiomyopathy, introduction of implantable defibrillators to prevent sudden death as well as high-benefit:low-risk septal reduction therapies to reverse heart failure have substantially reduced morbidity and disease-related mortality (to 0.5% per year). For pulmonary arterial hypertension, a disease once characterized by a particularly grim prognosis, prospective randomized drug trials with aggressive single (or combined) pharmacotherapy have measurably improved survival and quality of life for many patients. In cardiac amyloidosis, development of disease-specific drugs can for the first time reduce morbidity and mortality, prominently with breakthrough ATTR-protein-stabilizing tafamidis. In conclusion, in less common and visible cardiovascular diseases, it is crucial to recognize substantial progress and achievement, given that penetration of such information into clinical practice and the patient community can be inconsistent. Diseases such as hypertrophic cardiomyopathy, pulmonary arterial hypertension, and ATTR cardiac amyloidosis, once linked to a uniformly adverse prognosis, are now associated with the opportunity for patients to experience satisfactory quality of life and extended longevity.

Left Ventricular Apical Aneurysms in Hypertrophic Cardiomyopathy: Equivalent Detection by Magnetic Resonance Imaging and Contrast Echocardiography

BACKGROUND

Left ventricular (LV) apical aneurysm is a unique morphological entity and novel adverse risk marker existing within the broad phenotypic spectrum of hypertrophic cardiomyopathy (HCM). Its true prevalence in the HCM population is likely underestimated because of inherent limitations of conventional noncontrast echocardiography. The authors hypothesized that contrast echocardiography is a reliable imaging technique compared with cardiovascular magnetic resonance (CMR) for the detection of apical aneurysms. The aim of this study was to assess the effectiveness of contrast echocardiography in the detection of LV apical aneurysms in patients with HCM in comparison with the gold standard, CMR.

METHODS

One hundred twelve patients with HCM identified from an institutional clinical database, who underwent echocardiographic and CMR examinations within 12 months and had LV apical aneurysms identified on either or both imaging modalities, were retrospectively analyzed. Discordant cases were reviewed by an expert panel, and a consensus was reached regarding the presence or absence of an apical aneurysm. The reason for any discrepancy was recorded.

RESULTS

The mean age of the patients was 59 ± 13 years, and 73% were men. Sixty-four (57%) underwent contrast echocardiography. The median interval between echocardiography and CMR was 118 days (interquartile range, 61-237 days). Thirty-nine patients (35%) had discordance between echocardiographic and CMR findings, of whom 20 had aneurysms reported on echocardiography but not CMR and 19 vice versa. Upon reanalysis by the expert panel, aneurysms were initially missed on CMR in 16 patients (80%), largely because of interpretation error secondary to small aneurysms, with a mean aneurysm size of 0.82 ± 0.38 cm in these cases. Before secondary review by the expert panel, contrast echocardiography had sensitivity of 97% compared with 85% for CMR (P = .0198) and 64% for noncontrast echocardiography (P = .0001). After secondary review, contrast echocardiography had sensitivity of 98% compared with 67% for noncontrast echocardiography (P = .0001) and 97% for CMR (P = 1.00).

CONCLUSIONS

Contrast echocardiography has high sensitivity for detecting LV apical aneurysms and should be used routinely in the evaluation and risk stratification of patients with HCM.

Clinical prediction of genotypes in hypertrophic cardiomyopathy: A systematic review

INTRODUCTION

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac condition and the most common cause of sudden cardiac death (SCD) in patients below the age of 35. Genetic testing is a vital part of HCM diagnostics, yet correlation with clinical phenotypes remains complex. Identifying clinical predictors of informative genetic testing may prevent unnecessary investigations and improve cost-effectiveness of services. This article reviews the current literature pertinent to identifying such predictors.

METHODS

Five literature databases were screened using a suitably designed search strategy. Studies investigating the correlation between having a positive genetic test for HCM and a range of clinical and radiological parameters were included in the systematic review.

RESULTS

Twenty-nine observational studies of a total of 9,486 patients were included. The main predictors of informative genetic testing were younger age, higher septal thickness, reverse septal curvature, family history of HCM and SCD and the absence of hypertension. Two externally validated scoring systems have also been developed: the Mayo and Toronto scores. Novel imaging markers and complex algorithmic models are emerging predictors.

CONCLUSION

Using clinical predictors to decide whom to test is a feasible alternative to investigating all comers. Nonetheless, currently there is not enough evidence to unequivocally recommend for or against this strategy. Further validation of current predictors and identification of new ones remain open research avenues.

Identification of Potential miRNA-mRNA Regulatory Network Contributing to Hypertrophic Cardiomyopathy (HCM)

Background: Hypertrophic cardiomyopathy (HCM) is a myocardial disease with unidentified pathogenesis. Increasing evidence indicated the potential role of microRNA (miRNA)-mRNA regulatory network in disease development. This study aimed to explore the miRNA-mRNA axis in HCM.

Methods: The miRNA and mRNA expression profiles obtained from the Gene Expression Omnibus (GEO) database were used to identify differentially expressed miRNAs (DEMs) and genes (DEGs) between HCM and normal samples. Target genes of DEMs were determined by miRTarBase. Gene ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted to identify biological functions of the DEGs and DEMs. miRNA-mRNA regulatory network was constructed to identify the hub genes and miRNAs. Logistic regression model for HCM prediction was established basing on the network.

Results: A total of 224 upregulated and 366 downregulated DEGs and 10 upregulated and 14 downregulated DEMs were determined. We identified 384 DEM-targeted genes, and 20 of them were overlapped with the DEGs. The enriched functions include extracellular structure organization, organ growth, and phagosome and melanoma pathways. The four miRNAs and three mRNAs, including hsa-miR-373, hsa-miR-371-3p, hsa-miR-34b, hsa-miR-452, ARHGDIA, SEC61A1, and MYC, were identified through miRNA-mRNA regulatory network to construct the logistic regression model. The area under curve (AUC) values over 0.9 suggested the good performance of the model.

Conclusion: The potential miRNA-mRNA regulatory network and established logistic regression model in our study may provide promising diagnostic methods for HCM.

Cardiovascular Magnetic Resonance Imaging and Heart Failure

Purpose of Review

The purpose of this review is to summarize the application of cardiac magnetic resonance (CMR) in the diagnostic and prognostic evaluation of patients with heart failure (HF).

Recent Findings

CMR is an important non-invasive imaging modality in the assessment of ventricular volumes and function and in the analysis of myocardial tissue characteristics. The information derived from CMR provides a comprehensive evaluation of HF. Its unique ability of tissue characterization not only helps to reveal the underlying etiologies of HF but also offers incremental prognostic information.

Summary

CMR is a useful non-invasive tool for the diagnosis and assessment of prognosis in patients suffering from heart failure.

Diagnostic yield of hypertrophic cardiomyopathy in first-degree relatives of decedents with idiopathic left ventricular hypertrophy

AIMS

Idiopathic left ventricular hypertrophy (LVH) is defined as LVH in the absence of myocyte disarray or secondary causes. It is unclear whether idiopathic LVH represents the phenotypic spectrum of hypertrophic cardiomyopathy (HCM) or whether it is a unique disease entity. We aimed to ascertain the prevalence of HCM in first-degree relatives of decedents from sudden death with idiopathic LVH at autopsy. Decedents also underwent molecular autopsy to identify the presence of pathogenic variants in genes implicated in HCM.

METHODS AND RESULTS

Families of 46 decedents with idiopathic LVH (125 first-degree relatives) were investigated with electrocardiogram, echocardiogram exercise tolerance test, cardiovascular magnetic resonance imaging, 24-h Holter, and ajmaline provocation test. Next-generation sequencing molecular autopsy was performed in 14 (30%) cases. Decedents with idiopathic LVH were aged 33 ± 14 years and 40 (87%) were male. Fourteen families (30%) comprising 16 individuals were diagnosed with cardiac disease, including Brugada syndrome (n = 8), long QT syndrome (n = 3), cardiomyopathy (n = 2), and Wolff-Parkinson-White syndrome (n = 1). None of the family members were diagnosed with HCM. Molecular autopsy did not identify any pathogenic or likely pathogenic variants in genes encoding sarcomeric proteins. Two decedents had pathogenic variants associated with long QT syndrome, which were confirmed in relatives with the clinical phenotype. One decedent had a pathogenic variant associated with Danon disease in the absence of any histopathological findings of the condition or clinical phenotype in the family.

CONCLUSION

Idiopathic LVH appears to be a distinct disease entity from HCM and is associated with fatal arrhythmias in individuals with primary arrhythmia syndromes. Family screening in relatives of decedents with idiopathic LVH should be comprehensive and encompass the broader spectrum of inherited cardiac conditions, including channelopathies.

[LEOPARD syndrome]

LEOPARD syndrome with multiple lentigines (cardiomyopathic lentiginosis) is a rare, genetically predetermined disease with autosomal dominant inheritance. Prevalence of this syndrome is unknown. One of pathognomonic clinical manifestations of this syndrome is the presence of multiple lentiginous pigment spots all over the body. The most common cardiac manifestation (approximately 80%) is myocardial hypertrophy. We presented a rare clinical case of detecting LEOPARD syndrome with multiple lentigines in a 32-year old female patient with major manifestations evident as pronounces morpho-functional alterations, myocardial hypertrophy, and heart rhythm disorders.

Markers of responsiveness to disopyramide in patients with hypertrophic cardiomyopathy

BACKGROUND

Significant left-ventricular outflow tract obstruction (LVOTO) in hypertrophic cardiomyopathy (HCM) may result in symptoms and is associated with adverse outcomes. Although disopyramide can reduce resting gradients, nearly 30% of HCM patients do not respond. We sought to study the clinical and echocardiographic variables associated with disopyramide-induced LVOT-gradient reduction.

METHODS

Forty-one disopyramide-treated HCM patients (average daily-dose 305 mg) were subdivided into two groups: (1) nineteen responders, with a reduction of LVOT-gradients of at least 30% from baseline, and (2) twenty-two non-responders, in whom LVOT-gradients did not change or increased following treatment. All patients had a thorough clinical and echocardiographic assessment pre- and post-treatment initiation.

RESULTS

Patients who responded to disopyramide had better pretreatment left ventricular (LV) systolic function (LV ejection fraction of 67.9 ± 5.6% vs. 59.7 ± 5.8%, p = 0.0001), better LV global longitudinal strain (-17.9 ± 2.3% vs. -16.1 ± 2.5%, p = 0.048), less mitral regurgitation, smaller LV size (indexed LV end-systolic volume of 16.2 ± 5.1 ml/m² vs. 23.2 ± 6.8 ml/m², p = 0.001), and lower LV maximal wall thickness (17.2±3 mm vs.19.2 ± 3.4 mm, p = 0.046). Baseline left atrial (LA) volumes were significantly lower in the responders, with higher indices of LA ejection fraction (62 ± 11.2% vs. 50.5 ± 12.2%, p = 0.005), systolic LA strain (34 ± 12.4% vs. 25.8 ± 10.6%, p = 0.04), and LA strain-rate (1.34 ± 0.49%/sec vs. 0.99 ± 0.24%/sec, p = 0.012). In multivariable analysis, the presence of reduced LV systolic function and systolic LA strain-rate remained independently associated with poor response to disopyramide.

CONCLUSIONS

Obstructive HCM patients with more severe disease at baseline tend to respond less to disopyramide treatment. In those patients, early referral for alcohol septal ablation or myectomy surgery should be considered.

Advances in MRI Applications to Diagnose and Manage Cardiomyopathies

PURPOSE OF REVIEW

The prevalence of heart failure continues to rise, and imaging characterization of the cardiomyopathic process is important for identifying myocardial disease, initiating appropriate treatment, and improving outcomes. We aimed to summarize recent advances in cardiac magnetic resonance imaging (CMR) applications for the diagnosis, characterization, and implications on management of various cardiomyopathies.

RECENT FINDINGS

Parametric mapping by CMR has emerged as an important advancement in quantification of myocardial fibrosis, increased extracellular space, and myocardial edema. In addition, improved assessment of myocardial function with myocardial strain assessment may provide early identification of patients at risk and determining responsiveness to therapeutic interventions. Novel MRI techniques and the advent of artificial intelligence may help to uncover important mechanistic insights into the cardiomyopathic process. Innovative CMR techniques continue to evolve, and it will be of interest to determine how these advances can be incorporated into clinical practice to improve diagnosis, treatment, and management of patients with cardiomyopathies.

Assessment of the healing process after percutaneous implantation of a cardiovascular device: a systematic review

The healing process, occurring after intra-cardiac and intra-vascular device implantation, starts with fibrin condensation and attraction of inflammatory cells, followed by the formation of fibrous tissue that slowly covers the device. The duration of this process is variable and may be incomplete, which can lead to thrombus formation, dislodgement of the device or stenosis. To better understand this process and the neotissue formation, animal models were developed: small (rats and rabbits) and large (sheep, pigs, dogs and baboons) animal models for intra-vascular device implantation; sheep and pigs for intra-cardiac device implantation. After intra-vascular and intra-cardiac device implantation in these animal models, in vitro techniques, i.e. histology, which is the gold standard and scanning electron microscopy, were used to assess the device coverage, characterize the cell constitution and detect complications such as thrombosis. In humans, optical coherence tomography and intra-vascular ultrasounds are both invasive modalities used after stent implantation to assess the structure of the vessels, atheroma plaque and complications. Non-invasive techniques (computed tomography and magnetic resonance imaging) are in development in humans and animal models for tissue characterization (fibrosis), device remodeling evaluation and device implantation complications (thrombosis and stenosis). This review aims to (1) present the experimental models used to study this process on cardiac devices; (2) focus on the in vitro techniques and invasive modalities used currently in humans for intra-vascular and intra-cardiac devices and (3) assess the future developments of non-invasive techniques in animal models and humans for intra-cardiac devices.

Quantification of mitral regurgitation in patients with hypertrophic cardiomyopathy using aortic and pulmonary flow data: impacts of left ventricular outflow tract obstruction and different left ventricular segmentation methods

BACKGROUND

Cardiovascular magnetic resonance (CMR) imaging in patients with hypertrophic cardiomyopathy (HCM) enables the assessment of not only left ventricular (LV) hypertrophy and scarring but also the severity of mitral regurgitation. CMR assessment of mitral regurgitation is primarily based on the difference between LV stroke volume (LVSV) and aortic forward flow (Ao) measured using the phase-contrast (PC) technique. However, LV outflow tract (LVOT) obstruction causing turbulent, non-laminar flow in the ascending aorta may impact the accuracy of aortic flow quantification, leading to false conclusions regarding mitral regurgitation severity. Thus, we decided to quantify mitral regurgitation in patients with HCM using Ao or, alternatively, main pulmonary artery forward flow (MPA) for mitral regurgitation volume (MRvol) calculations.

METHODS

The analysis included 143 prospectively recruited subjects with HCM and 15 controls. MRvol was calculated as the difference between LVSV computed with either the inclusion (LVSVincl) or exclusion (LVSVexcl) of papillary muscles and trabeculations from the blood pool and either Ao (MRvolAoi or MRvolAoe) or MPA (MRvolMPAi or MRvolMPAe). The presence or absence of LVOT obstruction was determined based on Doppler echocardiography findings.

RESULTS

MRvolAoi was higher than MRvolMPAi in HCM patients with LVOT obstruction [47.0 ml, interquartile range (IQR) = 31.5-60.0 vs. 35.5 ml, IQR = 26.0-51.0; p < 0.0001] but not in non-obstructive HCM patients (23.0 ml, IQR = 16.0-32.0 vs. 24.0 ml, IQR = 15.3-32.0; p = 0.26) or controls (18.0 ml, IQR = 14.3-21.8 vs. 20.0 ml, IQR = 14.3-22.0; p = 0.89). In contrast to controls and HCM patients without LVOT obstruction, in HCM patients with LVOT obstruction, aortic flow-based MRvol (MRvolAoi) was higher than pulmonary-based findings (MRvolMPAi) (bias = 9.5 ml; limits of agreement: -11.7-30.7 with a difference of 47 ml in the extreme case). The differences between aortic-based and pulmonary-based MRvol values calculated using LVSVexcl mirrored those derived using LVSVincl. However, MRvol values calculated using LVSVexcl were lower in all the groups analyzed (HCM with LVOT obstruction, HCM without LVOT obstruction, and controls) and with all methods of MRvol quantification used (p ≤ 0.0001 for all comparisons).

CONCLUSIONS

In HCM patients, LVOT obstruction significantly affects the estimation of aortic flow, leading to its underestimation and, consequently, to higher MRvol values than those obtained with MPA-based MRvol calculations.

Imaging of Left Ventricular Hypertrophy: a Practical Utility for Differential Diagnosis and Assessment of Disease Severity

PURPOSE OF REVIEW

Left ventricular hypertrophy (LVH) is often encountered in clinical practice, and it is a risk factor for cardiac mortality and morbidity. Determination of the etiology and disease severity is important for the management of patients with LVH. The aim of this review is to show the remarkable progress in cardiac imaging and its importance in clinical practice.

RECENT FINDINGS

This review focuses on clinical features and characteristic cardiac imaging in LVH caused by various diseases including hypertension, aortic valve stenosis, hypertrophic cardiomyopathy, and secondary cardiomyopathies. The usefulness of echocardiography as a tool of general versatility including hemodynamic evaluation and the usefulness of cardiac magnetic resonance imaging for assessment of cardiac morphology and myocardial tissue characteristics of relevance for LVH are described. Imaging modalities now have central roles in the differentiation and prognostic assessment of LVH.

Modern Imaging Techniques in Cardiomyopathies

Modern advanced imaging techniques have allowed increasingly more rigorous assessment of the cardiac structure and function of several types of cardiomyopathies. In contemporary cardiology practice, echocardiography and cardiac magnetic resonance imaging are widely used to provide a basic framework in the evaluation and management of cardiomyopathies. Echocardiography is the quintessential imaging technique owing to its unique ability to provide real-time images of the beating heart with good temporal resolution, combined with its noninvasive nature, cost-effectiveness, availability, and portability. Cardiac magnetic resonance imaging provides data that are both complementary and uniquely distinct, thus allowing for insights into the disease process that until recently were not possible. The new catchphrase in the evaluation of cardiomyopathies is multimodality imaging, which is purported to be the efficient integration of various methods of cardiovascular imaging to improve the ability to diagnose, guide therapy, or predict outcomes. It usually involves an integrated approach to the use of echocardiography and cardiac magnetic resonance imaging for the assessment of cardiomyopathies, and, on occasion, single-photon emission computed tomography and such specialized techniques as pyrophosphate scanning.

A novel PRKAG2 mutation in a Chinese family with cardiac hypertrophy and ventricular pre-excitation

PRKAG2 syndrome is a rare autosomal dominant inherited disorder that is characterized by cardiac hypertrophy, ventricular pre-excitation and conduction system abnormalities. There is little knowledge in cardiovascular magnetic resonance (CMR) characteristics of PRKAG2 cardiomyopathy. This study investigated the genetic defect in a three-generation Chinese family with cardiac hypertrophy and ventricular pre-excitation using whole-exome sequencing. A novel missense mutation, c.1006 G > T (p.V336L), was identified in PRKAG2. This mutation had not been identified in the ExAC database, and the prediction result of MutationTaster indicated a deleterious effect. Furthermore, it cosegregated with the disease in the present family and was absent in unrelated 300 healthy controls. cDNA analysis did not detect any splicing defects, although the variant occurred in the first base of exon 9. CMR evaluation in five affected members showed diffuse hypertrophy in a concentric pattern, with markedly increased left ventricular mass above age and gender limits (median 151.3 g/m², range 108.4–233.4 g/m²). Two patients in progressive stage and one patient with sudden cardiac death exhibited extensive subendocardial late gadolinium enhancement. In conclusion, molecular screening for PRKAG2 mutations should be considered in patients who exhibit cardiac hypertrophy coexisting with ventricular pre-excitation. CMR offers promising advantages for evaluation of PRKAG2 cardiomyopathy.

Nonobstructive Hypertrophic Cardiomyopathy Out of the Shadows: Known from the Beginning but Largely Ignored … Until Now

Hypertrophic cardiomyopathy was first recognized as a disease of obstruction to left ventricular outflow, hence, its early names and acronyms such as idiopathic hypertrophic subaortic obstruction. The nonobstructive subset of patients, incapable of developing mechanical impedance to left ventricular outflow at rest or with physiologic exercise, was initially recognized by the Braunwald group at the National Institutes of Health >50 years ago in the preimaging era, and is now recognized as comprising about one-third of hypertrophic cardiomyopathy patients. Nevertheless, until recently, and for 25 years, this substantial patient subset has been largely ignored and incompletely understood in terms of its clinical significance and consequences. However, the newfound interest in nonobstructive hypertrophic cardiomyopathy with recent cohort data permits more robust clarity of this subset, as well as the overall disease spectrum. As a group, patients with nonobstructive disease experience a largely stable clinical course at relatively low risk for progressive heart failure symptoms to New York Heart Association class III/IV in (90%). On the other hand, there is a small but important subgroup of 10% at risk for developing drug-refractory advanced heart failure sufficient to justify consideration for heart transplant as the only definitive treatment option. This recognition closes a significant gap in understanding the natural history of hypertrophic cardiomyopathy, also underscoring that the disease is not uniformly grim but instead consistent with extended longevity, thereby providing many patients with a measure of reassurance.