Unexplained Left Ventricular Hypertrophy Research Articles

Diversity of heart failure phenotypes in transthyretin amyloid cardiomyopathy. More than just heart failure with preserved ejection fraction

Introduction Current guidelines recommend suspecting transthyretin amyloid cardiomyopathy (ATTR-CM) in patients over 65 years of age with unexplained left ventricular (LV) hypertrophy in a non-dilated LV, heart failure (HF) and preserved ejection fraction (HFpEF), hypertrophic cardiomyopathy or severe aortic stenosis. However, there is evidence indicating a high prevalence of ATTR-CM in other HF phenotypes. As such, this study aimed to characterize the diversity of HF phenotypes of ATTR-CM by examining the LV ejection fraction and LV dilatation using echocardiography. Methods This multicentre, retrospective observational study included patients diagnosed with ATTR-CM between 2015–2023. The diagnosis was based on a positive cardiac biopsy or positive bone scintigraphy without monoclonal gammopathy. Echocardiographic measurements were categorized according to LV ejection fraction (LVEF) into HFpEF (LVEF ≥50%), HF with mildly reduced EF (HFmrEF, LVEF 40–49%), and HF with reduced EF (HFrEF, LVEF <40%). LV cavity size was categorized by LV end-diastolic diameter (LVEDD) and volume index (LVEDVi) as normal, moderately increased and severe dilatation. Results The study included 135 patients with ATTR-CM (mean age, 78 years; 89% male; 89% wild-type ATTR-CM). Most patients were screened for ATTR-CM because of unexplained HF and increased LV wall thickness (57%). Echocardiography showed LVEF <50% in 60% of the patients, with a significant portion presenting with HFrEF. Patients with LVEF <50% had higher NYHA class and elevated N-terminal pro-B-type natriuretic peptide levels than HFpEF patients. LV dilatation was observed in 43% of the patients, with 10% presenting with both LVEF <50% and severe LV dilatation. Conclusion This study revealed significant variability in HF phenotypes among patients with ATTR-CM, from HFpEF without LV dilatation to HFrEF with severe LV dilatation. Relying solely on HFpEF for screening may lead to under-diagnosis. These findings suggest the need for more comprehensive diagnostic criteria beyond echocardiographic measures to improve ATTR-CM detection and management.

Screening for Fabry disease in patients with left ventricular hypertrophy in China: A multicentre and prospective study.

Left ventricular hypertrophy (LVH) is frequently detected via echocardiography in individuals with Fabry disease (FD), sometimes leading to confusion with hypertrophic cardiomyopathy (HCM) of other aetiologies. Considering this diagnosis challenge, FD should be included in the list of differential diagnosis for patients presenting with LVH. To address this concern, we conducted a prospective screening study in China, using dried blood spot (DBS) testing, to evaluate patients with unexplained LVH. Our study was designed as a nationwide, multicentre prospective investigation. A total of 1015 patients from 55 different centres who were diagnosed with LVH by echocardiography were screened in the study from September 2022 to December 2023. Demographic information, biochemistry data, echocardiography parameters and clinical observations were meticulously collected from all participants. The DBS method was used to assess α-galactosidase A (α-Gal A) activity in males and both α-Gal A and globotriaosylsphingosine (lyso-Gb3) levels in females. The final screening population included 906 patients (589 males, 65%) with LVH, characterized by a mean maximal myocardial thickness of 14.8±4.6mm and an average age of 56.9±17.2years. In total, 43 patients (38 males, 5 females) exhibited low α-Gal A activity measurement (<2.2μmol/L), while 21 patients (10 males, 11 females) presented low α-Gal A activity or elevated lyso-Gb3 levels (>1.1ng/mL). Among these patients, eight individuals (7 males and 1 female) were genetically confirmed to harbour pathogenic GLA mutations, resulting in a total prevalence of 0.88%. Compared with patients without FD, patients with FD tended to have proteinuria (75% vs. 21.2%, P=0.001), family history of HCM (37.5% vs. 2.3%, P<0.01) and neuropathic pain (37.5% vs. 4.4%, P<0.01) but lower systolic blood pressure (118.5±12.5 vs. 143.3±29.3mmHg, P=0.017). Five mutations were previously recognized as associated with FD while the remaining two, p.Asp313Val (c.938A>T) and c.547+3A>G, were deemed potentially pathogenic. Subsequent familial validation post-diagnosis identified an additional 14 confirmed cases. This pioneering screening study for FD among Chinese patients with unexplained LVH using DBS measurement, revealed an FD detection rate of 0.88%. Our findings confirmed that the combined measurement of lyso-Gb3 and α-Gal A activity is beneficial for primary screening of FD in patients with LVH. Given the availability of efficacious therapies and the value of cascade screening in extended families, early detection of FD in LVH patients is clinically important.

Epidemiological Changes in Transthyretin Cardiac Amyloidosis: Evidence from In Vivo Data and Autoptic Series.

Cardiac amyloidosis is an infiltrative disease that causes progressive myocardial impairment secondary to amyloid fibril deposition in the extracellular space of the myocardium. Many amyloid precursors, including transthyretin protein, are known to determine cardiac damage by aggregating and precipitating in cardiac tissue. Transthyretin cardiac amyloidosis may be either caused by rare genetic mutations of the transthyretin gene in the hereditary variant, or may arise as a consequence of age-related mechanisms in the acquired form. Although it has been labeled as a rare disease, in recent years, transthyretin cardiac amyloidosis has stood out as an emerging cause of aortic stenosis, unexplained left ventricular hypertrophy and heart failure with preserved ejection fraction, particularly in the elderly. Indeed, the integration of data deriving from both in vivo imaging techniques (whose advancement in the last years has allowed to achieve an easier and more accessible non-invasive diagnosis) and forensic studies (showing a prevalence of amyloid deposition in cardiac tissue of elderly patients up to 29%) suggests that cardiac amyloidosis is a more common disease than traditionally considered. Thanks to all the improvements in non-invasive diagnostic techniques, along with the development of efficacious therapies offering improvements in survival rates, transthyretin cardiac amyloidosis has been transformed from an incurable and infrequent condition to a relatively more diffuse and treatable disease, which physicians should take into consideration in the differential diagnostic processes in daily clinical practice.

Echocardiographic Strain Abnormalities Precede Left Ventricular Hypertrophy Development in Hypertrophic Cardiomyopathy Mutation Carriers.

Hypertrophic cardiomyopathy (HCM) is a genetic disease characterized by unexplained left ventricular hypertrophy (LVH), diastolic dysfunction, and increased sudden-death risk. Early detection of the phenotypic expression of the disease in genetic carriers without LVH (Gen+/Phen-) is crucial for emerging therapies. This clinical study aims to identify echocardiographic predictors of phenotypic development in Gen+/Phen-. Sixteen Gen+/Phen- (one subject with troponin T, six with myosin heavy chain-7, and nine with myosin-binding protein C3 mutations), represented the study population. At first and last visit we performed comprehensive 2D speckle-tracking strain echocardiography. During a follow-up of 8 ± 5 years, five carriers developed LVH (LVH+). At baseline, these patients were older than those who did not develop LVH (LVH-) (30 ± 8 vs. 15 ± 8 years, p = 0.005). LVH+ had reduced peak global strain rate during the isovolumic relaxation period (SRIVR) (0.28 ± 0.05 vs. 0.40 ± 0.11 1/s, p = 0.048) and lower global longitudinal strain (GLS) (-19.8 ± 0.4 vs. -22.3 ± 1.1%; p < 0.0001) than LVH- at baseline. SRIVR and GLS were not correlated with age (overall, p > 0.08). This is the first HCM study investigating subjects before they manifest clinically significant or relevant disease burden or symptomatology, comparing at baseline HCM Gen+/Phen- subjects who will develop LVH with those who will not. Furthermore, we identified highly sensitive, easily obtainable, age- and load-independent echocardiographic predictors of phenotype development in HCM gene carriers who may undergo early preventive treatment.

Transthyretin Amyloid Cardiomyopathy – Setting the Diagnosis Step by Step

Introduction: Transthyretin amyloid cardiomyopathy (ATTR-CM) can be diagnosed in the absen-ce of histology with typical echocardiographic fi ndings and skeletal scintigraphy showing grade 2 or 3 myocardial tracer uptake, when clonal plasma cell dyscrasia is excluded. Aim: To present a patient diagnosed with ATTR-CM, who was hospitalized with clinical signs of congestive heart failure. Case Report: An 84-year-old man was hospitalized with clinical signs of heart failure. Echocardiography showed concentric left ventricular hypertrophy (LVH) with reduced systolic function, along with impaired LV global longitudinal strain (GLS) with apical sparing (-9.9%). Serum and urine protein electrophoresis with immunofi xation were obtained and were negative for plasma cell dyscrasia. Bone scintigraphy showed similar radiotracer uptake in the myocar-dium and ribs (Perugini grade 2). The diagnosis of ATTR-CM was confi rmed. Conclusion: ATTR-CM is an underdiagnosed condition and should be suspected in patients with heart failure and unexplained LVH.

Phenotypic Spectrum of Subclinical Sarcomere-Related Hypertrophic Cardiomyopathy and Transition to Overt Disease.

Genetic hypertrophic cardiomyopathy (HCM) is classically caused by pathogenic/likely pathogenic variants in sarcomere genes (G+). Currently, HCM is diagnosed if there is unexplained left ventricular (LV) hypertrophy with LV wall thickness ≥15 mm in probands or ≥13 mm in at-risk relatives. Although LV hypertrophy is a key feature, this binary metric does not encompass the full constellation of phenotypic features, particularly in the subclinical stage of the disease. Subtle phenotypic manifestations can be identified in sarcomere variant carriers with normal LV wall thickness, before diagnosis with HCM (G+/LV hypertrophy-; subclinical HCM). We conducted a systematic review to summarize current knowledge about the phenotypic spectrum of subclinical HCM and factors influencing penetrance and expressivity. Although the mechanisms driving the development of LV hypertrophy are yet to be elucidated, activation of profibrotic pathways, impaired relaxation, abnormal Ca2+ signaling, altered myocardial energetics, and microvascular dysfunction have all been identified in subclinical HCM. Progression from subclinical to clinically overt HCM may be more likely if early phenotypic manifestations are present, including ECG abnormalities, longer mitral valve leaflets, lower global E' velocities on Doppler echocardiography, and higher serum N-terminal propeptide of B-type natriuretic peptide. Longitudinal studies of variant carriers are critically needed to improve our understanding of penetrance, characterize the transition to disease, identify risk predictors of phenotypic evolution, and guide the development of novel treatment strategies aimed at influencing disease trajectory.

Identification of a novel likely pathogenic TPM1 variant linked to hypertrophic cardiomyopathy in a family with sudden cardiac death.

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant genetic cardiac disorder characterized by unexplained left ventricular hypertrophy. It can cause a wide spectrum of clinical manifestations, ranging from asymptomatic to heart failure and sudden cardiac death (SCD). Approximately half of HCM cases are caused by variants in sarcomeric proteins, including α-tropomyosin (TPM1). In this study, we aimed to characterize the clinical and molecular phenotype of HCM in an Iranian pedigree with SCD. The proband and available family members underwent comprehensive clinical evaluations, including echocardiography, cardiac magnetic resonance (CMR) imaging and electrocardiography (ECG). Whole-exome sequencing (WES) was performed in all available family members to identify the causal variant, which was validated, and segregation analysis was conducted via Sanger sequencing. WES identified a novel missense variant, c.761A>G:p.D254G (NM_001018005.2), in the TPM1 gene, in the proband, his father and one of his sisters. Bioinformatic analysis predicted it to be likely pathogenic. Clinical features in affected individuals were consistent with HCM. The identification of a novel TPM1 variant in a family with HCM and SCD underscores the critical role of genetic screening in at-risk families. Early detection of pathogenic variants can facilitate timely intervention and management, potentially reducing the risk of SCD in individuals with HCM.

Echocardiography in Hypertrophic Cardiomyopathy

Abstract Hypertrophic cardiomyopathy (HCM) is a common disorder characterized by unexplained left ventricular hypertrophy. The disease can have different phenotypic expressions and can be genetic in nature with autosomal dominant inheritance. It usually runs a benign course in the majority but can lead to heart failure, atrial fibrillation, and sudden cardiac death (SCD). Echocardiography plays a key role in the diagnosis and overall management of the condition. It is useful in diagnosis, differentiation of different types (obstructive vs nonobstructive), in systematic evaluation of associated abnormalities (like mitral regurgitation), helps in selection of appropriate treatment and is helpful in guiding the intervention procedures for the condition. Certain echocardiographic measures are predictors of SCD. The review describes in detail the techniques and nuances of performing a comprehensive echocardiographic evaluation of patients with HCM.

Prevalence and Predictors of Readmissions in Patients With Hypertrophic Cardiomyopathy and Atrial Fibrillation/Flutter

Atrial fibrillation/flutter (AF) is the most common dysrhythmia in patients with hypertrophic cardiomyopathy (HCM). Unexplained left ventricular hypertrophy and left ventricular outflow tract obstruction are integral components of HCM pathology which can cause increased left atrial pressure and atrial myopathy contributing to the substrate for AF. We aimed to determine the impact of AF on hospital readmissions in patients with HCM. We conducted a retrospective analysis using the 2015 to 2019 Nationwide Readmission Database to analyze the effect of AF on 30-day readmission and causes of 30-day readmission in patients with HCM. We also determined the hospital, patient, and procedure-specific independent predictors of readmission in patients with HCM and AF. Of 191,235 index HCM hospitalizations, 81,390 (42.6%) had a secondary diagnosis of AF. A total of 16.9% of patients with HCM and AF were readmitted within 30 days as compared with 14% of HCM patients without AF. The presence of AF was independently associated with a higher risk of all-cause 30-day readmission (hazard ratio [HR] 1.21, 95% confidence interval [CI] 1.17 to 1.25, p <0.001). The foremost etiology of 30-day readmission in HCM patients with AF was hypertensive heart and chronic kidney disease with heart failure, whereas the foremost etiology of 30-day readmission in HCM patients without AF was sepsis. Interventions aimed toward AF management (electrical cardioversion: adjusted HR 0.91, 95% CI 0.82 to 1.01. p = 0.074, AF ablation: HR 0.92, 95% CI 0.74 to 1.13, p = 0.409, Watchman procedure: HR 1.50, 95% CI 0.16 to 14.6, p = 0.725) during index admission did not significantly impact the 30-day readmission in HCM patients with AF. Myectomy during index hospitalization (adjusted HR 0.54, 95% CI 0.34 to 0.86, p = 0.010) was most strongly associated with a lower risk of 30-day readmission in HCM patients with AF. In conclusion, in patients hospitalized for HCM, presence of AF was associated with excess risk of 30-day all-cause readmission. Interventions aimed toward HCM management, that is, myectomy rather than interventions aimed toward AF management predicted lower readmission rate in this patient population.

Multinational experience with next-generation sequencing: opportunity to identify transthyretin cardiac amyloidosis and Fabry disease.

Sarcomeric hypertrophic cardiomyopathy (HCM) must be differentiated from phenotypically similar conditions because clinical management and prognosis may greatly differ. Patients with unexplained left ventricular hypertrophy require an early, confirmed genetic diagnosis through diagnostic or predictive genetic testing. We tested the feasibility and practicality of the application of a 17-gene next-generation sequencing (NGS) panel to detect the most common genetic causes of HCM and HCM phenocopies, including treatable phenocopies, and report detection rates. Identification of transthyretin cardiac amyloidosis (ATTR-CA) and Fabry disease (FD) is essential because of the availability of disease-specific therapy. Early initiation of these treatments may lead to better clinical outcomes. In this international, multicenter, cross-sectional pilot study, peripheral dried blood spot samples from patients of cardiology clinics with an unexplained increased left ventricular wall thickness (LVWT) of ≥13 mm in one or more left ventricular myocardial segments (measured by imaging methods) were analyzed at a central laboratory. NGS included the detection of known splice regions and flanking regions of 17 genes using the Illumina NextSeq 500 and NovaSeq 6000 sequencing systems. Samples for NGS screening were collected between May 2019 and October 2020 at cardiology clinics in Colombia, Brazil, Mexico, Turkey, Israel, and Saudi Arabia. Out of 535 samples, 128 (23.9%) samples tested positive for pathogenic/likely pathogenic genetic variants associated with HCM or HCM phenocopies with double pathogenic/likely pathogenic variants detected in four samples. Among the 132 (24.7%) detected variants, 115 (21.5%) variants were associated with HCM and 17 (3.2%) variants with HCM phenocopies. Variants in MYH7 (n=60, 11.2%) and MYBPC3 (n=41, 7.7%) were the most common HCM variants. The HCM phenocopy variants included variants in the TTR (n=7, 1.3%) and GLA (n=2, 0.4%) genes. The mean (standard deviation) ages of patients with HCM or HCM phenocopy variants, including TTR and GLA variants, were 42.8 (17.9), 54.6 (17.0), and 69.0 (1.4) years, respectively. The overall diagnostic yield of 24.7% indicates that the screening strategy effectively identified the most common forms of HCM and HCM phenocopies among geographically dispersed patients. The results underscore the importance of including ATTR-CA (TTR variants) and FD (GLA variants), which are treatable disorders, in the differential diagnosis of patients with increased LVWT of unknown etiology.

Case of Hypertrophic Cardiomyopathy with Clinical Progression to Restrictive Physiology

Abstract Hypertrophic cardiomyopathy (HCM) is defined as an unexplained left ventricular (LV) hypertrophy ≥15 mm (13 mm if family history present) occurring in the absence of identifiable factor that may account for LV wall thickening, including pressure overload and infiltrative or storage disorder. Restrictive physiology is a pattern of ventricular filling with increased myocardial stiffness leading to elevation of ventricular pressure, causing diastolic dysfunction. A 60-year-old man was brought to the hospital with progressive worsening breathlessness for 2 days and bilateral lower limb swelling. The patient was a known case of HCM, ischemic heart disease (IHD) with single-vessel disease – ostial D1 70% stenosis, atrial fibrillation (AF), status post radiofrequency ablation, moderate LV systolic dysfunction (ejection fraction [EF] – 30%), with recurrent admission due to heart failure. The patient presented with hypotension and bilateral lower limb swelling, and systemic examination showed bilateral crepitations. The patient was diagnosed with acute decompensated heart failure, heart failure with reduced EF, HCM, old IHD, and AF with controlled ventricular rate. Serial two-dimensional echocardiography showed the progression of HCM to restrictive physiology. The patient deteriorated and was planned for a heart transplant with bridging LV assist device therapy. The transition is not usually reported, and literature related to this is scarce; hence, this case is being reported.

Clinical red flags associated with transthyretin amyloid cardiomyopathy in patients with left ventricular hypertrophy: results of the TTRACK study

Abstract Background Transthyretin amyloid cardiomyopathy (ATTR-CM) is a life-threatening, systemic disorder that results in progressive physical disability, substantially reduced quality of life, and high morbidity and mortality rates. ATTR-CM is an underrecognized cause of increased left ventricular (LV) wall thickness in older adults, and delayed diagnosis can lead to worse clinical outcomes. To facilitate early identification of patients with LV hypertrophy (LVH) at risk for ATTR-CM, greater recognition of diagnostic ‘red flags’ is required. Purpose To determine the association between diagnostic red flags and ATTR-CM in patients with LVH. Methods TTRACK is a multicentre, non-interventional epidemiological study (ClinicalTrials.gov: NCT03842163). Eligible patients were ≥50 years of age and had unexplained LVH (LV maximum wall thickness ≥15 mm [echocardiogram]). After undergoing technetium-99m-DPD/-PYP/-HMDP-labelled bone scintigraphy, scans were categorized by the degree of tracer uptake in the heart; Perugini grades 0, 1, 2 and 3 represented absent, low, moderate and high uptake, respectively. Immunofixation electrophoresis was used to detect monoclonal protein abnormalities; grade 2 and 3 scans without evidence of monoclonal gammopathy were considered diagnostic for ATTR-CM. The frequency of predetermined clinical disease markers was compared in patients without monoclonal protein abnormalities and grade 0 or grade 2/3 scans. Results Of 766 eligible patients with scintigraphy data, 521 (68.0%) had grade 0 cardiac uptake; 37 (4.8%) had grade 1; and 208 (27.2%) had grade 2/3. Among patients with moderate/high uptake, 137 (65.9% of those with grade 2/3 uptake; 17.9% of the overall cohort) had no monoclonal protein abnormalities (ATTR-CM); 56 (26.9%) had monoclonal gammopathy of undetermined significance or light chain amyloidosis; and 15 (7.2%) patients had unknown monoclonal test findings. On univariable analysis, carpal tunnel syndrome (odds ratio [95% CI], 27.7 [16.7, 46.1]), permanent atrial fibrillation (3.4 [2.2, 5.2]), male sex (2.9 [1.8, 4.8]) and advanced heart failure (1.8 [1.2, 2.9]) were the strongest predictors for grade 2/3 scans; on multivariable analysis, carpal tunnel syndrome (50.3 [23.4, 108.0]), male sex (9.1 [3.9, 21.3] and age (1.7 [1.4, 2.1]) were the strongest predictors (Figure). Conclusions In the TTRACK study, 18% of patients ≥50 years of age with unexplained LVH ≥15 mm had ATTR-CM. Carpal tunnel syndrome, male sex and advanced age were associated with a greater likelihood of ATTR-CM.

Abstract 14403: Echocardiographic Predictors of Phenotype Development in Hypertrophic Cardiomyopathy Mutation-Carriers

Introduction: Hypertrophic cardiomyopathy (HCM) is a hereditary disease characterized by unexplained left ventricular (LV) hypertrophy (LVH). Genetic family screening of probands identifies mutation carriers (Gen+) without phenotype (Phen-), who require clinical follow-up. Hypothesis: Identification of early phenotype signs may facilitate clinical management of Gen+/Phen-. We assessed if echocardiography LV global longitudinal strain (GLS) and strain rate (SR) may predict LVH development in Gen+/Phen- HCM. Methods: We identified 16 Gen+/Phen- (25% women; age 20±11 years). Echocardiogram was performed at baseline, when no phenotype was evident, and repeated yearly. The end of follow up was the HCM diagnosis date in subjects who developed HCM (FU-Phen+) and the last visit date in those who didn’t develop HCM (FU-Phen-). Mitral inflow peak E and A velocities and Tissue Doppler E’ and A’ peak velocities were measured. LV GLS and SR-peak during isovolumic relaxation (SRIVR) were calculated offline independently by two investigators blind to the clinical data. Results: GLS and SRIVR were not age-dependent (p=0.08 and 0.55, respectively), whereas E/E’ ratio was directly related to age (p=0.011). During follow-up (8±5 years, interquartile range 5-10 years) 5 subjects became FU-Phen+. At baseline, FU-Phen+ compared to FU-Phen- were older and had higher maximal wall thickness, higher EF, less negative GLS and lower SRIVR (Table). Abnormal baseline GLS, despite a normal EF, and reduced SRIVR indicate reduced systolic deformation and covert diastolic dysfunction which may be caused by disarray preceding LVH and fibrosis. Conclusions: This is the first HCM preclinical study to compare at baseline HCM Gen+/Phen- subjects who will develop to those who will not develop LVH. We identified sensitive, easily obtainable, age- and load-independent echocardiographic predictors of phenotype development in HCM gene carriers who may undergo early preventive treatment.

Abstract 16660: Precision Diagnosis of Hypertrophic Cardiomyopathy: A New Definition of Inappropriate Hypertrophy

Introduction: The definition of hypertrophic cardiomyopathy (HCM), unaltered for 50 years, requires unexplained left ventricular hypertrophy with a maximum wall thickness (MWT) ≥15mm in probands. However, this doesn’t consider age, sex and body-size which is inadequate for a precision therapy era. Aim: To develop a personalised definition of inappropriate hypertrophy using cardiac MRI and evaluate potential care implications. Methods: Healthy reference cardiac MRIs from the Framingham Heart Study, UK Biobank, and multiple healthy volunteer studies were analysed by a validated AI algorithm. Generalized additive mixed models accounting for age, sex, and body surface area (BSA) established a personalized hypertrophy threshold for MWT (&gt;95% prediction interval) and conditional Z-scores. We assessed the discordance in HCM diagnosis between a “≥15mm” and “personalized hypertrophy” threshold applied to the UK Biobank and clinical HCM cohorts. Results: In healthy subjects (n=5,255), 36% of MWT variation was explained by age, sex and BSA. In the UK Biobank (n=44,690), using ≥15mm, there is a substantial sex skew; 8% of males and 1% of females are classified as hypertrophic. With a personalized threshold, this reduces to 3% of males and 2% of females classified as hypertrophic. 17% of subjects have a predicted hypertrophy threshold of 15mm (with 46% predicted ≤ 14mm, 37% predicted ≥16mm). In clinical HCM cohorts (n=1,854) across 5 centres in 4 countries (UK, USA, Italy, Portugal), females had thinner hearts (17.7 vs 19.1mm; p&lt;0.001) but more relative hypertrophy evidenced by greater deviation (Z-scores) from their predicted MWT (5.4 vs 5.1; p=0.05). Conclusion: We propose a new, personalised definition for hypertrophy that mitigates for significant age, sex and BSA confounding inherent in a 15mm cut point. We have identified potential for under/over diagnosis in a population cohort and suboptimal risk stratification in smaller, younger and/or female HCM patients.

Hypertrophic Cardiomyopathy Diagnosis and Treatment in High- and Low-Income Countries: A Narrative Review.

Hypertrophic cardiomyopathy (HCM) is a hereditary cardiac condition characterized by unexplained left ventricular hypertrophy without a hemodynamic cause. This condition is prevalent in the United States, resulting in various clinical manifestations, including diastolic dysfunction, left ventricular outflow obstruction, cardiac ischemia, and atrial fibrillation. HCM is associated with several genetic mutations, with sarcomeric mutations being the most common and contributing to a more complex disease course. Early diagnosis of HCM is essential for effective management, as late diagnosis often requires invasive treatments and creates a substantial financial burden.Disparities in HCM diagnosis and treatment exist between high-income and low-income countries. High-income countries have more resources to investigate and implement advanced diagnostic and treatment modalities. In contrast, low-income countries face challenges in accessing diagnostic equipment, trained personnel, and affordable medications, leading to a lower quality of life and life expectancy for affected individuals. Diagnostic tools for HCM include imaging studies such as 2D echocardiography, cardiovascular magnetic resonance (CMR), and electrocardiograms (ECGs). CMR is considered the gold standard but remains inaccessible to a significant portion of the world's population, especially in low-income countries. Genetics plays a crucial role in HCM, with numerous mutations identified in various genes. Genetic counseling is essential but often limited in low-income countries due to resource constraints. Disparities in healthcare access and adherence to treatment recommendations exist between high-income and low-income countries, leading to differences in patient outcomes. Addressing these disparities is essential to improve the overall management of HCM on a global scale. In conclusion, this review highlights the complex nature of HCM, emphasizing the importance of early diagnosis, genetic counseling, and access to appropriate diagnostic and therapeutic interventions. Addressing healthcare disparities is crucial to ensure that all individuals with HCM receive timely and effective care, regardless of their geographic location or socioeconomic status.

Difficulties in Diagnosing Fabry Disease in Patients with Unexplained Left Ventricular Hypertrophy (LVH): Is the Novel GLA Gene Mutation a Pathogenic Mutation or Polymorphism?

Fabry disease (FD) is an X-linked, lysosomal glycosphingolipid storage disorder that occurs very rarely. Cardiac involvement may comprise of left ventricular hypertrophy (LVH), arrhythmias, conduction abnormalities, heart failure and valvular abnormalities. The goal of this study was to conduct gene analysis for FD in patients suffering from unexplained LVH. 120 patients over the age of 30 who were diagnosed by echocardiography with idiopathic LVH were included in the study. Patients with severe hypertension, intermediate valve disease such as moderate aortic stenosis, known FD, and a family history of autosomal dominant hypertrophic cardiomyopathy were excluded from the study. GLA gene mutations were studied by Sanger sequence analysis in all patients. Of the 120 total patients included in this study, 69 were female (58%) and 51 were male (42%). The mean age was 60.3 ± 15.7. GLA gene mutations were detected in three male patients. The detected mutations are as follows: NM_000169.2:IVS6-10G>A (c.1000-10G>A), NM_000169.2:c.937G>T (p.D313Y) (p.Asp313Tyr) and NM_000169.2:c.941A>T (p.K314M) (p.Lys314Met). Early diagnosis is of vital importance in FD, which can be treated with enzyme replacement. Genetic screening in patients diagnosed with idiopathic LVH by echocardiography is important in the early diagnosis and treatment of FD. Patients over 30 years of age with idiopathic LVH should be screened for FD. Various new polymorphisms can be detected in genetic screening. Identifying new polymorphisms is important for knowing the true mutations in FD.

BS-452758-1 SUPPRESSION-REPLACEMENT GENE THERAPY REVERSE REMODELS THE INTRACELLULAR CALCIUM HANDLING DISEASE PHENOTYPE OF TNNT2-MEDIATED HYPERTROPHIC CARDIOMYOPATHY

Hypertrophic cardiomyopathy (HCM), characterized by otherwise unexplained left ventricular hypertrophy, has a prevalence of 1:500. Pathogenic variants in TNNT2-encoded cardiac troponin T causes a thin filament subtype of sarcomeric HCM. A key cellular feature of the pathological remodeling in TNNT2-mediated HCM involves dysregulation of intracellular calcium handling in ventricular cardiomyocytes (CMs). To develop a TNNT2 “suppression-replacement (SupRep)” gene therapy to reverse the intracellular calcium perturbations associated with thin filament, sarcomeric HCM using induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs) derived from a patient with TNNT2-R288P-mediated HCM. Custom-designed TNNT2 targeting shRNAs were tested for knockdown (KD) efficiency using TSA201 cells and RT-qPCR. A dual-component SupRep TNNT2 gene therapy was created by cloning into a single construct a custom-designed TNNT2 shRNA that produced greatest KD (suppression) and a “shRNA-immune” (shIMM) TNNT2 cDNA (replacement). Patient-specific TNNT2-R288P and CRISPR/Cas9 variant-corrected isogenic control (IC) iPSC-CMs were generated from a patient with HCM. The intracellular calcium indicator, Fluo-4, was used to detect intracellular free calcium. Our lead TNNT2-shRNA had an 80% KD efficiency of TNNT2. TNNT2-R288P iPSC-CMs treated with TNNT2-SupRep showed a similar KD efficiency. Compared to the IC iPSC-CMs, the TNNT2-R288P iPSC-CMs showed increased irregular events (30.4% vs. 10.9%, p<0.0001), prolonged calcium transient duration 90 (CTD90, 1.01 ± 0.03 s vs. 0.89 ± 0.02 s, p<0.0001) and prolonged peak to 90% decay time (0.57 ± 0.02 s vs. 0.49 ± 0.01 s, p=0.0012). Compared to untreated cells, transfection with TNNT2-SupRep gene therapy, the TNNT2-R288P iPSC-CMs showed a decrease in irregular events (30.4% vs. 14%, p<0.0001), shortened CTD90 (1.01 ± 0.03 s vs. 0.91 ± 0.01 s, p=0.003), and shortened peak to 90% decay time (0.57 ± 0.02 s vs. 0.50 ± 0.02 s, p=0.02). There was no significant difference in irregular events, CTD90, or peak to 90% decay time between TNNT2-R288P iPSC-CMs treated with TNNT2-SupRep and IC iPSC-CMs. Here, we provide the first proof-of-principle SupRep gene therapy for TNNT2-mediated HCM. TNNT2-SupRep gene therapy almost fully restored the impaired intracellular calcium handling properties of TNNT2-R288P patient-derived iPSC-CMs back to the normal state achieved by the CRISPR/Cas9 gene-edited cure.

Stage-specific therapy for hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is the most common inherited myocardial disease and is defined by otherwise unexplained left ventricular hypertrophy. The main complications include heart failure and arrhythmias such as atrial fibrillation and ventricular arrhythmias. Current treatment rests on septal reduction therapies, prevention of sudden cardiac death through implantable cardioverter defibrillator, and use of drugs such as beta-blockers, calcium antagonists, or amiodarone. In the last years, new pharmacological agents specifically targeting the pathophysiology of the disease have been developed with encouraging results in terms of functional capacity and symptoms improvement from clinical trials. In this review, we summarize the possible treatment approaches for each phase of the natural history of the disease: pre-phenotype expression, classic phenotype, adverse remodelling, and overt dysfunction.

Long QTc in hypertrophic cardiomyopathy: A consequence of structural myocardial damage or a distinct genetic disease?

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disease, characterized by the presence of unexplained left ventricular hypertrophy. This condition is often associated with electrocardiographic abnormalities including QTc prolongation occurring in 13% of patients. The main explanation for prolonged QTc in HCM is myocardial hypertrophy and the related structural damage. However, other mechanisms, including long QT syndrome (LQTS) genes mutations, may be involved. In the present study we explored the hypothesis of a distinct genetic basis underlying QTc prolongation in HCM by investigating the potential co-inheritance of pathogenic gene variants associated with LQTS and HCM. For this purpose, starting from a cohort of 150 HCM patients carrying pathogenic variants in sarcomere genes, we selected 25 patients carrying a QTc prolongation unexplained by any other cause. The QTc was considered prolonged if greater than 450 ms in males and greater than 470 ms in females. The NGS analysis was performed with Illumina TrueSight Cardio panel genes on Illumina MiniSeq platform. We identified pathogenic/likely pathogenic variants in the KCNQ1 in two patients (c.1781G > A, p. Arg594Gln; c.532G > A, p. Ala178Thr) (8%). Variants of uncertain significance were identified in SCN5A, KCNJ5, AKAP9 and ANK2 in four patients (16%). Although the results are limited by the small number of patients included in the study, they highlight a minor contribution of LQTS genes for QTc prolongation in HCM patients. The screening for ion channel genes mutations may be considered in HCM patients with prolonged QTc unexplained by any other cause. This in-depth molecular diagnosis may contribute to improve risk stratification and treatment planning.

РЕЗУЛЬТАТЫ ЭЛЕКТРОКАРДИОГРАФИЧЕСКОГО ИССЛЕДОВАНИЯ ПРИ ГКМП У РАЗНОВОЗРАСТНЫХ КОШЕК

Cardiomyopathies are a heterogeneous group of myocardial diseases with varying phenotypes and prognosis. Feline cardiomyopathies are common, and cardiovascular disease is among the 10 most common causes of death in cats. Hypertrophic cardiomyopathy (HCM) is a common cause of heart failure, arterial thromboembolism, and sudden death in cats. HCM is a primary myocardial lesion characterized by unexplained left ventricular hypertrophy (LVH) and impaired myocardial relaxation. The cause of primary or idiopathic in cats is unknown, but hereditary pathology probably exists in many cases. The disease is widespread in breeds such as Maine Coon, Persian, Ragdoll, American Shorthair. There are also reports of HCM in littermates and other close relatives of domestic shorthair cats. The method of electrocardiography is quite sensitive in the diagnosis of cardiomyopathies in humans, therefore, the study of ECG signs of HCM in cats, as well as the study of the dynamics of disease progression, the development and improvement of the treatment of this disease is an urgent scientific and practical problem in veterinary medicine, which has not been sufficiently resolved to date. According to the obtained ECG data, it can be concluded that recording in animals of different ages, as well as in animals that have a hereditary predisposition to the development of this disease, can play a key role in diagnosing an early stage of cardiomyopathy. The prevalence of HCM in cats with a predisposition to this disease is much higher than in cats without this genetic predisposition. Further studies involving more cats with HCM, secondary left ventricular hypertrophy, and normal hearts are proposed to better understand the heterogeneity and complexity of this myocardial disease.