Prevalence and Progression of Late Gadolinium Enhancement in Children and Adolescents With Hypertrophic Cardiomyopathy

Impaired Myocardial Work in Children with Hypertrophic Cardiomyopathy and Left Ventricular Fibrosis on Cardiac Magnetic Resonance Imaging

Echocardiography is pivotal for diagnosis and monitoring of hypertrophic cardiomyopathy (HCM) and can evaluate myocardial function using myocardial work (MW) calculations. Echocardiography is often supplemented by cardiovascular magnetic resonance (CMR) imaging, which can detect myocardial fibrosis using late gadolinium enhancement (LGE). We sought to study the relationship between baseline LGE and MW at baseline and during follow-up in pediatric HCM patients. During the study period (2008-2023), 75 patients were followed up for HCM. In 14 patients (age 14.2 ± 2.8 years, 50.0% male, 6.4 ± 2.9 years follow-up), both LGE-CMR and echocardiography were performed. Global work index (GWI), global constructive work (GCW), global wasted work, and global work efficiency (GWE) were measured, and myocardial fibrosis was estimated by qualitative assessment of LGE. Patients with LGE (n = 7) exhibited significantly impaired baseline MW, including GWI (mean difference, MD - 487.4 mmHg %, 95% CI [- 866.8 mmHg % to - 108.3 mmHg %], p = 0.027), GCW (MD - 536.8 mmHg %, 95% CI [- 929.8 mmHg % to - 144.4 mmHg %], p = 0.020), and GWE (MD - 4.4%, 95% CI [- 8.1% to - 0.7%], p = 0.039). Regional analysis revealed impaired MW indices in segments with LGE, notably basal and mid septal segments. GWI demonstrated high diagnostic performance for LGE presence (sensitivity 93%, specificity 88%, and area under receiver operating characteristic curve 0.85). Baseline LGE presence had no significant impact on MW deterioration during follow-up. MW is significantly impaired in HCM patients with myocardial fibrosis, highlighting potential utility of echocardiography-derived MW analysis as a valuable tool.

The Role of Cardiovascular Magnetic Resonance Imaging in Athletic Individuals-A Narrative Review

Cardiovascular magnetic resonance imaging (MRI) is an advanced cardiac imaging modality that is often required when evaluating athletic individuals. Unrestricted imaging planes, excellent spatial resolution, and a lack of ionising radiation are some of the benefits of this modality. Cardiac MRI has been established as the gold standard imaging modality for morphological assessment, volumetric analysis, and tissue characterisation. Cardiac MRI without any doubt is an excellent diagnostic tool when evaluating athletes with symptoms or those individuals exhibiting equivocal findings at screening. It is also useful for athletes who fall within the grey zone and is especially important among athletes with a suspected or confirmed diagnosis. Cardiac MRI plays a strategic role when adopting a shared decision-making model in athletes with heart disease, tailoring and personalising medical care to the condition and the athlete's wishes. The aim of this review is to provide a comprehensive yet practical overview of the role of cardiac MRI when evaluating athletes in clinic.

Scanner-generated native T1 mapping: a novel approach for assessing myocardial fibrosis in coronary heart disease

Background

To investigate the feasibility of using native longitudinal relaxation time (T1) mapping values, derived from the Picture Archiving and Communication System (PACS), for assessing diffuse myocardial fibrosis in patients with coronary heart disease (CHD).

Materials and methods

Patients with CHD group were retrospectively enrolled as the experimental group, while age- and sex-matched healthy individuals were included as the control group. Based on the results of late gadolinium enhancement (LGE) sequence from cardiac magnetic resonance (CMR) imaging, the CHD group was further stratified into two subgroups: the LGE positive group (LGE+) and the LGE negative group (LGE-). The correlation between native T1 values and extracellular volume (ECV) values were assessed using the Pearson correlation coefficient.

Results

A total of 60 patients with coronary heart disease (age 54.03 ± 9.86 years) were included in the analysis, of whom 30 had late gadolinium enhancement (LGE+) and 30 did not (LGE-). The control group consisted of 42 healthy subjects (age 52.14 ± 7.41 years). Compared with the control group, both native T1 and extracellular volume (ECV) values were significantly increased in the CHD group (P < 0.05). The native T1 value was positively correlated with the ECV value (r = 0.711, P < 0.01). In the LGE+ subgroup, native T1 and ECV values were significantly higher than those in the control group (P < 0.001). The area under the receiver operating characteristic curve (AUC) for native T1 was 0.763. The optimal diagnostic threshold for native T1, as measured by the Picture Archiving and Communication System (PACS), was 1,275.50 ms, with a sensitivity of 93.3% and a specificity of 63.3%.

Conclusions

The diagnostic performance of scanner-generated native T1 Mapping demonstrates robust accuracy and holds potential as a non-invasive tool for evaluating diffuse myocardial fibrosis in patients with CHD.

Prognostic role of novel variables in sudden cardiac death risk associated to hypertrophic cardiomyopathy

INTRODUCTION

Models for estimating the risk of sudden cardiac death (SCD) in pediatric hypertrophic cardiomyopathy (HCM) used in our setting do not consider some parameters of routine clinical practice. The objective was to identify non-classical risk factors and evaluate their prognostic value.

PATIENTS AND METHODS

Retrospective observational study, including patients with isolated HCM 0-18 years old, evaluating clinical, genetic, and imaging variables. The risk of SCD or major arrhythmic cardiac events (MACEs) was estimated according to the three most widely used European models (HCM Risk-SCD, European Society of Cardiology [ESC] algorithm, and HCM Risk-Kids), analyzing their predictive capacity by adding genotyping and advanced cardiac imaging parameters.

RESULTS

The sample included 77 patients followed up for 5.25 years. Ten (13%) experienced a MACE. We found that MACE was significantly associated with myocardial deformation and positive genotype status, and associated, although not significantly, to late gadolinium enhancement (LGE) in cardiac MRI (P = .062). Events were more frequent (hazard ratio = 18.5; P = .006) and occurred earlier (P = .022) in association with variants in genes other than MYBPC3. The inclusion of "genotype other than MYBPC3" and "presence of LGE" improved the predictive capacity of the models for the high-risk (C-statistic 0.94 vs 0.84 with HCM Risk-SCD; 0.88 vs 0.74 with ESC algorithm; 0.90 vs 0.80 with HCM Risk-Kids) and intermediate-risk categories (C-statistic 0.88 vs 0.51 with HCM Risk-SCD; 0.85 vs 0.64 with ESC algorithm; 0.84 vs 0.51 with HCM Risk-Kids).

CONCLUSIONS

The predictive capacity of European risk models improves by incorporating the variables "genotype other than MYBPC3" and "presence of LGE", although larger studies are required to validate their prognostic value.

Valsartan and Cardiac Remodeling in Early-Stage Hypertrophic Cardiomyopathy: The VANISH Randomized Clinical Trial Cardiac Magnetic Resonance Substudy

Importance

Valsartan has been shown to attenuate phenotypic progression among individuals with early-stage sarcomeric hypertrophic cardiomyopathy (HCM). Myocardial tissue characterization by cardiac magnetic resonance (CMR) imaging may enhance mechanistic insights, but whether valsartan influences these parameters remains uncertain.

Objective

To evaluate the treatment effects of valsartan on myocardial structure, function, and tissue parameters in early-stage sarcomeric HCM.

Design, Setting, and Participants

This prespecified CMR substudy of the VANISH (Valsartan for Attenuating Disease Evolution in Early Sarcomeric Hypertrophic Cardiomyopathy) randomized clinical trial evaluated treatment effects of valsartan vs placebo on myocardial structure, function, and tissue parameters and was conducted from April 2014 through July 2019 at 17 international sites. Individuals aged 8 to 45 years with early-stage HCM aged between 8 and 45 years and with no or minimal symptoms were eligible for inclusion.

Interventions

Treatment with placebo or valsartan (80 mg per day for children weighing <35 kg, 160 mg per day for children weighing ≥35 kg, or 320 mg per day for adults aged 18 years or older).

Main Outcomes and Measures

The primary outcome was mean change in CMR parameters between baseline and year 2, including indexed extracellular volume (iECV), indexed intracellular volume (iICV), and late gadolinium enhancement (LGE). Mean between-group differences in CMR parameters between baseline and year 2 were evaluated using multivariable mixed-effects linear regression models.

Results

Overall, 137 of 178 VANISH participants (77.0%) underwent CMR imaging at baseline and year 2. Among these participants, mean (SD) age was 23 (10) years, and 51 participants (37.2%) were female. Baseline characteristics and CMR parameters were well balanced between treatment groups. Higher LGE, iECV, and iICV at baseline were associated with higher cardiac biomarker levels and more pronounced cardiac remodeling. Between baseline and year 2, valsartan appeared to increase left ventricular (LV) end-diastolic volume index (mean difference [MD], 3.3 mL/m2; 95% CI, 0.4-6.2; P = .03), suggesting treatment benefit, but did not significantly impact LV mass index (MD, -2.9 g/m2; 95% CI, -6.1 to 0.2; P = .07) or LV ejection fraction. Similarly, valsartan appeared to reduce decline in right ventricular volumes. Valsartan appeared to significantly reduce iICV progression (MD, -5.0 mL/m2; 95% CI, -9.7 to -0.4; P = .03), but did not impact iECV (MD, 0.0 mL/m2; 95% CI, -1.4 to 1.3; P = .95) or LGE progression (MD, 0.5%; 95% CI, -0.4 to 1.3; P = .30).

Conclusions and Relevance

These findings enhance mechanistic insights into the effect of valsartan in early-stage HCM, showing potential benefits on biventricular remodeling and myocardial intracellular volume. Further research to identify cellular mechanisms of valsartan on HCM progression is needed.

Trial Registration

ClinicalTrials.gov Identifier: NCT01912534.

Independent External Evaluation of Pediatric Hypertrophic Cardiomyopathy Risk Scores in Predicting Severe Ventricular Arrhythmias

BACKGROUND

Sudden cardiac death is the most common cause of death in childhood hypertrophic cardiomyopathy (HCM). Recently, 2 risk scores have been developed to estimate the 5-year risk of sudden cardiac death. We aimed to assess their respective performances in an independent cohort.

METHODS

All patients with HCM aged <18 years from a single center were retrospectively included between 2003 and 2023. HCM Risk-Kids and PRIMaCY risk scores were calculated at diagnosis and during follow-up. The primary composite outcome included sustained ventricular arrhythmia, appropriate implantable cardioverter defibrillator (ICD) therapy, aborted cardiac arrest, or sudden cardiac death.

RESULTS

A total of 100 primary prevention children were included (7.1±5.6 years, 59.0% males), with a mean follow-up of 8.6±5.5 years. Overall, 13 (13.0%) patients experienced the primary composite outcome. When only considering events during the 5 first years, Harrel C index was 0.52 (95% CI, 0.27-0.77) for HCM Risk-Kids (≥6%) and 0.70 (95% CI, 0.59-0.80) for PRIMaCY (>8.3%), with 1 patient potentially treated by ICD for every 25 ICDs implanted for HCM Risk-Kids and 1 for every 14 ICDs implanted for PRIMaCY. When risk scores were repeated and all primary outcomes during follow-up were considered, 12 of 13 (92.3%) events were correctly identified using both risk scores, with 1 patient potentially treated by ICD for every 5.6 ICDs implanted for HCM Risk-Kids and 1 for every 5.3 ICDs implanted for PRIMaCY. Among 44 (44.0%) patients implanted with an ICD, all primary prevention patients who had ≥1 appropriate ICD therapy during follow-up had an HCM Risk-Kids ≥6% and PRIMaCY >8.3% at implantation.

CONCLUSIONS

In this independent evaluation, our findings suggest imperfect discrimination between low and high-risk patients using the HCM Risk-Kids and PRIMaCY risk scores, with predicted risks tending to be overestimated compared with the actual observed events. The performance or risk scores was substantially improved by periodic reassessment during follow-up.

Factors associated with high-intensity physical activity and sudden cardiac death in hypertrophic cardiomyopathy

BACKGROUND

High-intensity physical activity has traditionally been discouraged in patients with hypertrophic cardiomyopathy due to concerns about triggering sudden cardiac death. However, current guidelines adopt a more liberal stance, and evidence on risk factors for exercise-related sudden cardiac death remains limited. This study investigated the clinical, morphological and genetic factors associated with high-intensity physical activity-related sudden cardiac death in hypertrophic cardiomyopathy.

METHODS

This retrospective study included 75 patients with documented sudden cardiac death events from a cohort of 2619 patients with hypertrophic cardiomyopathy evaluated between 2005 and 2023. Physical activity levels at the time of the sudden cardiac death event were classified as high-intensity (≥6 metabolic equivalents) or low-intensity to moderate-intensity. Clinical and imaging characteristics, cardiopulmonary exercise test findings and genetic data were compared between the groups.

RESULTS

Among the 75 patients, 15 (20%) experienced sudden cardiac death events during high-intensity activity. These patients were younger than those with events during low-intensity or moderate-intensity activity (median age: 25 (IQR 16-43) years vs 56 (48-64) years, p<0.001). High-intensity activity-related events were associated with higher European Society of Cardiology sudden cardiac death risk scores (median 4.9 vs 2.4, p=0.023) and fewer ventricular arrhythmias during exercise testing. However, there were no differences in the degree of left ventricular hypertrophy, left ventricular outflow tract obstruction, left ventricular systolic or diastolic function or genetic findings between groups. In multivariable analysis, younger age was the only independent risk factor of high-intensity activity-related sudden cardiac death events. Recurrent events in patients who survived initial high-intensity activity-related sudden cardiac death were triggered by subsequent high-intensity activity.

CONCLUSIONS

High-intensity physical activity-related sudden cardiac death in hypertrophic cardiomyopathy is associated with younger age; however, in this small cohort, no associations were found with traditional risk factors, including left ventricular hypertrophy or obstructive physiology.

The role of diagnostic modalities in differentiating hypertensive heart disease and hypertrophic cardiomyopathy: strategies in adults for potential application in paediatrics

Hypertensive heart disease and hypertrophic cardiomyopathy both lead to left ventricular hypertrophy despite differing in aetiology. Elucidating the correct aetiology of the presenting hypertrophy can be a challenge for clinicians, especially in patients with overlapping risk factors. Furthermore, drugs typically used to combat hypertensive heart disease may be contraindicated for the treatment of hypertrophic cardiomyopathy, making the correct diagnosis imperative. In this review, we discuss characteristics of both hypertensive heart disease and hypertrophic cardiomyopathy that may enable clinicians to discriminate the two as causes of left ventricular hypertrophy. We summarise the current literature, which is primarily focused on adult populations, containing discriminative techniques available via diagnostic modalities such as electrocardiography, echocardiography, and cardiac MRI, noting strategies yet to be applied in paediatric populations. Finally, we review pharmacotherapy strategies for each disease with regard to pathophysiology.

Myocardial Scarring and Sudden Cardiac Death in Young Patients With Hypertrophic Cardiomyopathy: A Multicenter Cohort Study

Importance

The ability to predict sudden cardiac death (SCD) in children and adolescents with hypertrophic cardiomyopathy (HCM) is currently inadequate. Late gadolinium enhancement (LGE) by cardiovascular magnetic resonance (CMR) imaging is associated with SCD events in adults with HCM.

Objective

To examine the prognostic significance of LGE in patients with HCM who are younger than 21 years.

Design, Setting, and Participants

This multicenter, retrospective cohort study was conducted from April 8, 2015, to September 12, 2022, in patients with HCM who were younger than 21 years and had undergone CMR imaging across multiple sites in the US, Europe, and South America. Observers of CMR studies were masked toward outcomes and demographic characteristics.

Exposure

Natural history of HCM.

Main Outcome and Measures

The primary outcome was SCD and surrogate events, including resuscitated cardiac arrest and appropriate discharges from an implantable defibrillator. Continuous and categorical data are expressed as mean (SD), median (IQR), or number (percentage), respectively. Survivor curves comparing patients with and without LGE were constructed by the Kaplan-Meier method, and likelihood of subsequent clinical events was further evaluated using univariate and multivariable Cox proportional hazards models.

Results

Among 700 patients from 37 international centers, median (IQR) age was 14.8 (11.9-17.4) years, and 518 participants (74.0%) were male. During a median (IQR) [range] follow-up period of 1.9 (0.5-4.1) [0.1-14.8] years, 35 patients (5.0%) experienced SCD or equivalent events. LGE was present in 230 patients (32.9%), which constituted an mean (SD) burden of 5.9% (7.3%) of left ventricular myocardium. The LGE amount was higher in older patients and those with greater left ventricular mass and maximal wall thickness; patients with LGE had lower left ventricular ejection fractions and larger left atrial diameters. The presence and burden of LGE was associated with SCD, even after correcting for existing risk stratification tools. Patients with 10% or more LGE, relative to total myocardium, had a higher risk of SCD (unadjusted hazard ratio [HR], 2.19; 95% CI, 1.59-3.02; P < .001). Furthermore, the addition of LGE burden improved the performance of the HCM Risk-Kids score (before LGE addition: 0.66; 95% CI, 0.58-0.75; after LGE addition: 0.73; 95% CI, 0.66-0.81) and Precision Medicine in Cardiomyopathy score (before LGE addition: 0.68; 95% CI, 0.49-0.77; after LGE addition: 0.73; 95% CI, 0.64-0.82) SCD predictive models.

Conclusions and Relevance

In this retrospective cohort study, quantitative LGE was a risk factor for SCD in patients younger than 21 years with HCM and improved risk stratification.

Advanced myocardial characterization and function with cardiac CT

Non-invasive imaging with characterization and quantification of the myocardium with computed tomography (CT) became feasible owing to recent technical developments in CT technology. Cardiac CT can serve as an alternative modality when cardiac magnetic resonance imaging and/or echocardiography are contraindicated, not feasible, inconclusive, or non-diagnostic. This review summarizes the current and potential future role of cardiac CT for myocardial characterization including a summary of late enhancement techniques, extracellular volume quantification, and strain analysis. In addition, this review highlights potential fields for research about myocardial characterization with CT to possibly include it in clinical routine in the future.

Myocardial Injury by COVID-19 Infection Assessed by Cardiovascular Magnetic Resonance Imaging - A Prospective Multicenter Study

BACKGROUND

This prospective multicenter study assessed the prevalence of myocardial injury in patients with COVID-19 using cardiac magnetic resonance imaging (CMR).

METHODS AND RESULTS

We prospectively screened 505 patients with moderate to severe COVID-19 disease from 7 hospitals in Japan. Of these patients, 31 (mean [±SD] age 63.5±10.4 years, 23 [74%] male) suspected of myocardial injury, based on elevated serum troponin or B-type natriuretic peptide concentrations either upon admission or 3 months after discharge, underwent CMR 3 months after discharge. The primary endpoint was the presence of myocardial injury, defined by any of the following: (1) contrast enhancement in the left or right ventricle myocardium on late gadolinium enhancement CMR; (2) left or right ventricular dysfunction (defined as <50% and <45%, respectively); and (3) pericardial thickening on contrast enhancement. The mean (±SD) duration between diagnosis and CMR was 117±16 days. The primary endpoint was observed in 13 of 31 individuals (42%), with 8 (26%) satisfying the modified Lake Louise Criteria for the diagnosis of acute myocarditis.

CONCLUSIONS

This study revealed a high incidence of myocardial injury identified by CMR in patients with moderate to severe COVID-19 and abnormal findings for cardiac biomarkers.

Society for Cardiovascular Magnetic Resonance 2023 Cases of SCMR case series

"Cases of SCMR" is a case series on the SCMR website (https://www.scmr.org) for the purpose of education. The cases reflect the clinical presentation and the use of cardiovascular magnetic resonance in the diagnosis and management of cardiovascular disease. The 2023 digital collection of cases is presented in this article.

Accelerated myocardial fibrosis in young to middle-aged patients with hypertrophic cardiomyopathy

BACKGROUND

The extent of late gadolinium enhancement (LGE) on cardiovascular magnetic resonance (CMR) in patients with hypertrophic cardiomyopathy (HCM) is associated with an increased risk of sudden cardiac death events. However, the clinical significance of age-specific longitudinal changes in LGE is not well characterized in HCM. We sought to assess whether the risk of LGE progression diverges between young to middle-aged (ages 20-59 years) and older (≥ 60) adults with HCM.

METHODS

A total of 102 HCM patients (age <60 years; n=75, age ≥60 years; n=27) undergoing serial CMR studies from two tertiary medical centers were evaluated. The median time interval between initial and follow-up CMR scans was 3.7 years. LGE was semiautomatically quantified by measuring regions with signal intensity >6 SD above the nulled remote myocardium and manually adjusting a grayscale threshold.

RESULTS

LGE was identified at baseline in 61 of the 102 HCM patients (60%), occupying 4.8 ± 3.9% of the left ventricular (LV) mass. At the end of the follow-up period, 53 of the 61 patients (87%) demonstrated an increase in the extent of LGE to 7.7 ± 5.4%, and 8 patients had no change. In 5 patients (5%), LGE increased to extensive with >15% of the LV mass. The rate of LGE progression was 0.7 ± 1.0%/year, including 21 patients (21%) with particularly accelerated progression of ≥1%/year. The risk of LGE progression ≥1%/year was significantly higher in patients <60 years than those ≥ 60 years (25% vs. 7%, p=0.03). The odds of LGE progression ≥1%/year was almost 4 times greater for patients <60 years compared with those ≥ 60 years (odds ratio, 4.2; 95%CI, 1.1-27.9). Age <60 years and LGE extent ≥ 10% were significant baseline predictors for future LGE progression ≥1%/year, even after adjustment for other potential risk factors.

CONCLUSION

In HCM, progressive fibrosis occurs more frequently in young to middle-aged patients, underscoring the importance of repeating CMR to re-evaluate for potential LGE progression in this age group.

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.

Prevalence and clinical significance of late gadolinium enhancement in children and adolescents with hypertrophic cardiomyopathy: a systematic review and meta-analysis

OBJECTIVES

Hypertrophic cardiomyopathy is the leading cause of sudden cardiac death among the paediatric population. The aim of this study is to investigate the prevalence and clinical significance of late gadolinium enhancement, as assessed by cardiac MRI, in paediatric hypertrophic cardiomyopathy.

METHODS

A systematic literature search was conducted in PubMed, SCOPUS, and Ovid SP to identify relevant studies. Pooled estimates with a 95% confidence interval were calculated using the random-effects generic inverse variance model. Statistical analysis was performed using Review Manager v5.4 and R programming.

RESULTS

Seventeen studies were included in this meta-analysis, encompassing a total of 778 patients. Late gadolinium enhancement was highly prevalent in paediatric hypertrophic cardiomyopathy, with a pooled prevalence of 51% (95% confidence interval, 40-62%). The estimated extent of focal fibrosis expressed as a percentage of left ventricular mass was 4.70% (95% confidence interval, 2.11-7.30%). The presence of late gadolinium enhancement was associated with an increased risk of adverse cardiac events (pooled odds ratio 3.49, 95% confidence interval 1.10-11.09). The left ventricular mass index of late gadolinium enhancement-positive group was higher than the negative group, with a standardised mean difference of 0.91 (95% confidence interval, 0.42-1.41).

CONCLUSION

This meta-analysis demonstrates that prevalence of late gadolinium enhancement in paediatric hypertrophic cardiomyopathy is similar to that in the adult population. The presence and extent of late gadolinium enhancement are independent predictors of adverse cardiac events, underscoring their prognostic significance among the paediatric population.

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.

Evaluation of new predictive scores for sudden cardiac death in childhood hypertrophic cardiomyopathy in a French cohort

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is rare in children, and sudden cardiac death (SCD) is difficult to predict. Two prognostic scores - HCM Risk-Kids and Precision Medicine for Cardiomyopathy (PRIMaCY) - were developed to assess the risk of SCD in the next 5 years in children with HCM.

AIMS

To test the ability of these scores to predict SCD in children with HCM. Also, to identify factors associated with a severe cardiac rhythmic event (SCRE) (ventricular fibrillation, sustained ventricular tachycardia, heart transplant for rhythmic reasons or SCD).

METHODS

Retrospective, multicentre, observational study at 10 medical centres in the Nord-Pas-de-Calais region, France.

RESULTS

This study included 72 paediatric patients with HCM during 2009-2019 who were followed for a median (interquartile range [IQR]) of 8.5 (5.0-16.2) years. Eleven patients (15.3%) presented with SCRE. HCM Risk-Kids was high, with a median (IQR) score of 6.2% (2.1-12.8%; significant threshold≥6.0%) and the PRIMaCY median (IQR) score was 7.1% (2.6-15.0%; significant threshold≥8.3%). The positive predictive value was only 27.1% (95% confidence interval [CI] 21.5-32.5%) for HCM Risk-Kids (with a threshold of≥6.0%) and 33.2% (95% CI 27.1-38.9%) for the PRIMaCY score (with a threshold of≥8.3%). The negative predictive values were 95.4% (95% CI 92.3-97.7%) and 93.0% (95% CI 89.8-96.2%), respectively. Three of 28 patients with an implantable cardioverter defibrillator (ICD) experienced complications (including inappropriate shocks).

CONCLUSION

HCM Risk-Kids and the PRIMaCY score have low positive predictive values to predict SCD in paediatric patients. If used alone, they could increase the rate of ICD implantation and thus ICD complications. Therefore, the scores should be used in combination with other data (genetic and magnetic resonance imaging results).

Cardiac MRI in diagnosis, prognosis, and follow-up of hypertrophic cardiomyopathy in children: current perspectives

Hypertrophic Cardiomyopathy (HCM) is an inherited myocardial disease characterised by left ventricular hypertrophy, which carries an increased risk of life-threatening arrhythmias and sudden cardiac death. The age of presentation and the underlying aetiology have a significant impact on the prognosis and quality of life of children with HCM, as childhood-onset HCM is associated with high mortality risk and poor long-term outcomes. Accurate cardiac assessment and identification of the HCM phenotype are therefore crucial to determine the diagnosis, prognostic stratification, and follow-up. Cardiac magnetic resonance (CMR) is a comprehensive evaluation tool capable of providing information on cardiac morphology and function, flow, perfusion, and tissue characterisation. CMR allows to detect subtle abnormalities in the myocardial composition and characterise the heterogeneous phenotypic expression of HCM. In particular, the detection of the degree and extent of myocardial fibrosis, using late-gadolinium enhanced sequences or parametric mapping, is unique for CMR and is of additional value in the clinical assessment and prognostic stratification of paediatric HCM patients. Additionally, childhood HCM can be progressive over time. The rate, timing, and degree of disease progression vary from one patient to the other, so close cardiac monitoring and serial follow-up throughout the life of the diagnosed patients is of paramount importance. In this review, an update of the use of CMR in childhood HCM is provided, focussing on its clinical role in diagnosis, prognosis, and serial follow-up.

Unique Aspects of Hypertrophic Cardiomyopathy in Children

Hypertrophic cardiomyopathy (HCM) is a primary heart muscle disease characterized by left ventricular hypertrophy that can be asymptomatic or with presentations that vary from left ventricular outflow tract obstruction, heart failure from diastolic dysfunction, arrhythmias, and/or sudden cardiac death. Children younger than 1 year of age tend to have worse outcomes and often have HCM secondary to inborn errors of metabolism or syndromes such as RASopathies. For children who survive or are diagnosed after 1 year of age, HCM outcomes are often favourable and similar to those seen in adults. This is because of sudden cardiac death risk stratification and medical and surgical innovations. Genetic testing and timely cardiac screening are paving the way for disease-modifying treatment as gene-specific therapies are being developed.

Transcriptome analysis of human hypertrophic cardiomyopathy reveals inhibited cardiac development pathways in children

The epidemiological, etiological, and clinical characteristics vary greatly between pediatric (P-HCM) and adult (A-HCM) hypertrophic cardiomyopathy (HCM) patients, and the understanding of the heterogeneous pathogenesis mechanisms is insufficient to date. In this study, we aimed to comprehensively assess the respective transcriptome signatures and uncover the essential differences in gene expression patterns among A-HCM and P-HCM. The transcriptome data of adults were collected from public data (GSE89714), and novel pediatric data were first obtained by RNA sequencing from 14 P-HCM and 9 infantile donor heart samples. Our study demonstrates the common signatures of myofilament or protein synthesis and calcium ion regulation pathways in HCM. Mitochondrial function is specifically dysregulated in A-HCM, whereas the inhibition of cardiac developing networks typifies P-HCM. These findings not only distinguish the transcriptome characteristics in children and adults with HCM but also reveal the potential mechanism of the higher incidence of septal defects in P-HCM patients.

Contemporary review on pediatric hypertrophic cardiomyopathy: insights into detection and management

Hypertrophic cardiomyopathy is the most common genetic cardiac disorder and is defined by the presence of left ventricular (LV) hypertrophy in the absence of a condition capable of producing such a magnitude of hypertrophy. Over the past decade, guidelines on the screening, diagnostic, and management protocols of pediatric primary (i.e., sarcomeric) HCM have undergone significant revisions. Important revisions include changes to the appropriate screening age, the role of cardiac MRI (CMR) in HCM diagnosis, and the introduction of individualized pediatric SCD risk assessment models like HCM Risk-kids and PRIMaCY. This review explores open uncertainties in pediatric HCM that merit further attention, such as the divergent American and European recommendations on CMR use in HCM screening and diagnosis, the need for incorporating key genetic and imaging parameters into HCM-Risk Kids and PRIMaCY, the best method of quantifying myocardial fibrosis and its prognostic utility in SCD prediction for pediatric HCM, devising appropriate genotype- and phenotype-based exercise recommendations, and use of heart failure medications that can reverse cardiac remodeling in pediatric HCM.

Focus on Paediatric Restrictive Cardiomyopathy: Frequently Asked Questions

Restrictive cardiomyopathy (RCM) is characterized by restrictive ventricular pathophysiology determined by increased myocardial stiffness. While suspicion of RCM is initially raised by clinical evaluation and supported by electrocardiographic and echocardiographic findings, invasive hemodynamic evaluation is often required for diagnosis and management of patients during follow-up. RCM is commonly associated with a poor prognosis and a high incidence of heart failure, and PH is reported in paediatric patients with RCM. Currently, only a few therapies are available for specific RCM aetiologies. Early referral to centres for advanced heart failure treatment is often necessary. The aim of this review is to address questions frequently asked when facing paediatric patients with RCM, including issues related to aetiologies, clinical presentation, diagnostic process and prognosis.

Cardiac Remodeling in Subclinical Hypertrophic Cardiomyopathy: The VANISH Randomized Clinical Trial

Importance

Valsartan has shown promise in attenuating cardiac remodeling in patients with early-stage sarcomeric hypertrophic cardiomyopathy (HCM). Genetic testing can identify individuals at risk of HCM in a subclinical stage who could benefit from therapies that prevent disease progression.

Objective

To explore the potential for valsartan to modify disease development, and to characterize short-term phenotypic progression in subclinical HCM.

Design, Setting, and Participants

The multicenter, double-blind, placebo-controlled Valsartan for Attenuating Disease Evolution in Early Sarcomeric Hypertrophic Cardiomyopathy (VANISH) randomized clinical trial was conducted from April 2014 to July 2019 at 17 sites in 4 countries (Brazil, Canada, Denmark, and the US), with 2 years of follow-up. The prespecified exploratory VANISH cohort studied here included sarcomere variant carriers with subclinical HCM and early phenotypic manifestations (reduced E' velocity, electrocardiographic abnormalities, or an increased left ventricular [LV] wall thickness [LVWT] to cavity diameter ratio) but no LV hypertrophy (LVH). Data were analyzed between March and December 2022.

Interventions

Treatment with placebo or valsartan (80 mg/d for children weighing <35 kg, 160 mg/d for children weighing ≥35 kg, or 320 mg/d for adults aged ≥18 years).

Main Outcomes and Measures

The primary outcome was a composite z score incorporating changes in 9 parameters of cardiac remodeling (LV cavity volume, LVWT, and LV mass; left atrial [LA] volume; E' velocity and S' velocity; and serum troponin and N-terminal prohormone of brain natriuretic peptide levels).

Results

This study included 34 participants, with a mean (SD) age of 16 (5) years (all were White). A total of 18 participants (8 female [44%] and 10 male [56%]) were randomized to valsartan and 16 (9 female [56%] and 7 male [44%]) were randomized to placebo. No statistically significant effects of valsartan on cardiac remodeling were detected (mean change in composite z score compared with placebo: -0.01 [95% CI, -0.29 to 0.26]; P = .92). Overall, 2-year phenotypic progression was modest, with only a mild increase in LA volume detected (increased by 3.5 mL/m2 [95% CI, 1.4-6.0 mL/m2]; P = .002). Nine participants (26%) had increased LVWT, including 6 (18%) who developed clinically overt HCM. Baseline LA volume index (LAVI; 35 vs 28 mL/m2; P = .01) and average interventricular septum thickness (8.5 vs 7.0 mm; P = .009) were higher in participants who developed HCM.

Conclusions and Relevance

In this exploratory cohort, valsartan was not proven to slow progression of subclinical HCM. Minimal changes in markers of cardiac remodeling were observed, although nearly one-fifth of patients developed clinically overt HCM. Transition to disease was associated with greater baseline interventricular septum thickness and LAVI. These findings highlight the importance of following sarcomere variant carriers longitudinally and the critical need to improve understanding of factors that drive disease penetrance and progression.

Trial Registration

ClinicalTrials.gov Identifier: NCT01912534.

Feasibility of gray-blood late gadolinium enhancement evaluation in young patients with congenital and acquired heart disease

Background

Late gadolinium enhancement (LGE) sequences have become common in pediatric cardiovascular magnetic resonance (CMR) to assess for myocardial fibrosis. Bright-blood late gadolinium enhancement (BB-LGE) by conventional phase-sensitive inversion recovery (PSIR) is commonly utilized, but similar inversion time (TI) value of fibrosis and left ventricular (LV) blood pool can make subendocardial areas difficult to assess. A gray-blood LGE (GB-LGE) technique has been described, targeting nulling of the LV blood pool and demonstrating improvement in ischemic scar detection over BB-LGE in adult patients. We sought to evaluate the feasibility of the GB-LGE technique in a young population with congenital and acquired heart disease and compare its ability to detect subendocardial scar to conventional BB-LGE.

Methods

Seventy-six consecutive patients referred for clinical CMR underwent both BB-LGE and GB-LGE on 1.5 T and 3 T scanners. Conventional PSIR sequences were obtained with TI to null the myocardium (BB-LGE) in short-axis and horizontal long-axis stacks. Same PSIR stacks were immediately repeated with TI to null the blood pool (GB-LGE). Both sequences were reviewed separately a week apart by two readers, blinded to the initial clinical interpretation. Studies were analyzed for overall image quality, confidence in scar detection, confidence in detection of LGE, LGE class, inter- and intra-observer agreement for the presence of scar, and intraclass correlation coefficient (ICC) for total scar burden.

Results

Overall confidence in myocardial scar detection by BB-LGE or GB-LGE as well as grading of image quality were not statistically different [(p = 1 and p = 1) and (p = 0.53, p = 0.18), respectively]. There was very good inter-observer agreement for the presence of scar on BB-LGE (K = 0.88, 95% CI 0.77-0.99) and GB-LGE (K = 0.84, 95% CI 0.7-0.96), as well as excellent intra-observer agreement for both readers (K = 0.93, 95% CI 0.87-0.99; and K = 0.81, 95% CI 0.69-0.95). Interclass correlation coefficient for total scar burden was excellent for BB-LGE (ICC = 0.98, 95% CI 0.96-0.99) and GB-LGE (ICC = 0.94, 95% CI 0.91-0.97).

Conclusions

The GB-LGE technique is feasible in the pediatric population with congenital and acquired heart disease. It can detect subendocardial/ischemic scar similar to conventional bright-blood PSIR sequences in the pediatric population.

Application of Cardiovascular Computed Tomography to the Assessment of Patients With Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is a common inherited cardiac condition in which regional myocardial thickening and scarring can lead to a range of symptoms including breathlessness, dizziness, chest pain, and collapse with loss of consciousness. It is vital to be able to understand the mechanisms behind these epiphenomena and to be able to distinguish, for example, between syncope because of arrhythmia versus syncope because of mechanical outflow tract obstruction. Therefore, we require a technique that can characterize anatomy, physiology, and myocardial substrate. Traditionally, this role has been the preserve of cardiac magnetic resonance (CMR) imaging. This review makes the case for cardiac computed tomography (CT) as an alternative imaging method. We review the use of functional CT to identify the components of outflow tract obstruction (and obstruction at other levels, which may be simultaneous), and as an aid to interventional and surgical planning. We demonstrate the added value of multiplanar isotropic reformats in this condition, particularly in cases where the diagnosis may be more challenging or where complications (such as early apical aneurysm) may be difficult to recognize with 2-dimensional techniques. In conclusion, our aim is to convince readers that cardiac CT is a highly valuable and versatile tool, which deserves wider usage and greater recognition in those caring for patients with hypertrophic cardiomyopathy.

Ventricular arrhythmias in patients with hypertrophic cardiomyopathy: Prevalence, distribution, predictors, and outcome

BACKGROUND

Hypertrophic cardiomyopathy (HCM) carries an increased risk of sudden cardiac death. Ventricular fibrillation (VF) is thought to be the common culprit arrhythmia.

OBJECTIVE

The purpose of this study was to describe the incidence and predictors of sustained ventricular arrhythmias (VTAs) in HCM patients.

METHODS

We retrospectively analyzed all patients with HCM and an implantable cardioverter-defibrillator (ICD) from a prospectively derived registry in 2 tertiary medical centers. Clinical, electrocardiographic, echocardiographic, ICD interrogation, and genetic data were collected and compared, first between patients with and without VTAs and then between patients with only VF and those with ventricular tachycardia (VT) with or without VF.

RESULTS

Of the 1328 HCM patients, 207 (145 [70%] male; mean age 33 ± 16 years) were implanted with ICDs. Over a mean follow-up of 10 ± 6 years, 37 patients with ICDs (18%) developed sustained VTAs. These were associated with a family history of sudden cardiac death and a personal history of VTAs (P = .036 and P = .001, respectively). Sustained monomorphic VT was the most common arrhythmia (n = 26, 70%) and was linked to decreased left ventricular (LV) ejection fraction and increased LV end-systolic and end-diastolic diameters. Antitachycardia pacing (ATP) successfully terminated 258 (79%) of the 326 VT events. Mortality rates were comparable between patients with and without VTAs (4 [11%] vs 29 [17%]; P = .42) and between those with and without ICDs (24 [16%] vs 85 [20%]; P = .367).

CONCLUSION

VT rather than VF is the most common arrhythmia in patients with HCM; it is amenable to ATP and is associated with lower LV ejection fraction and higher LV diameters. Therefore, ATP-capable devices may be considered in HCM patients with these LV features.

Cardiac imaging and biomarkers for assessing myocardial fibrosis in children with hypertrophic cardiomyopathy

BACKGROUND

Myocardial fibrosis, as diagnosed on cardiac magnetic resonance imaging (cMRI) by late gadolinium enhancement (LGE), is associated with adverse outcomes in adults with hypertrophic cardiomyopathy (HCM), but its prevalence and magnitude in children with HCM have not been established. We investigated: (1) the prevalence and extent of myocardial fibrosis as detected by LGE cMRI; (2) the agreement between echocardiographic and cMRI measurements of cardiac structure; and (3) whether serum concentrations of N-terminal pro hormone B-type natriuretic peptide (NT-proBNP) and cardiac troponin-T are associated with cMRI measurements.

METHODS

A cross-section of children with HCM from 9 tertiary-care pediatric heart centers in the U.S. and Canada were enrolled in this prospective NHLBI study of cardiac biomarkers in pediatric cardiomyopathy (ClinicalTrials.gov Identifier: NCT01873976). The median age of the 67 participants was 13.8 years (range 1-18 years). Core laboratories analyzed echocardiographic and cMRI measurements, and serum biomarker concentrations.

RESULTS

In 52 children with non-obstructive HCM undergoing cMRI, overall low levels of myocardial fibrosis with LGE >2% of left ventricular (LV) mass were detected in 37 (71%) (median %LGE, 9.0%; IQR: 6.0%, 13.0%; range, 0% to 57%). Echocardiographic and cMRI measurements of LV dimensions, LV mass, and interventricular septal thickness showed good agreement using the Bland-Altman method. NT-proBNP concentrations were strongly and positively associated with LV mass and interventricular septal thickness (P < .001), but not LGE.

CONCLUSIONS

Low levels of myocardial fibrosis are common in pediatric patients with HCM seen at referral centers. Longitudinal studies of myocardial fibrosis and serum biomarkers are warranted to determine their predictive value for adverse outcomes in pediatric patients with HCM.

The Role of Multimodality Imaging in Pediatric Cardiomyopathies

Cardiomyopathies are a heterogeneous group of myocardial diseases representing the first cause of heart transplantation in children. Diagnosing and classifying the different phenotypes can be challenging, particularly in this age group, where cardiomyopathies are often overlooked until the onset of severe symptoms. Cardiovascular imaging is crucial in the diagnostic pathway, from screening to classification and follow-up assessment. Several imaging modalities have been proven to be helpful in this field, with echocardiography undoubtedly representing the first imaging approach due to its low cost, lack of radiation, and wide availability. However, particularly in this clinical context, echocardiography may not be able to differentiate from cardiomyopathies with similar phenotypes and is often complemented with cardiovascular magnetic resonance. The latter allows a radiation-free differentiation between different phenotypes with unique myocardial tissue characterization, thus identifying the presence and extent of myocardial fibrosis. Nuclear imaging and computed tomography have a complementary role, although they are less used in daily clinical practice due to the concern related to the use of radiation in pediatric patients. However, these modalities may have some advantages in evaluating children with cardiomyopathies. This paper aims to review the strengths and limitations of each imaging modality in evaluating pediatric patients with suspected or known cardiomyopathies.

Cardiomyopathies in children: An overview

Paediatric cardiomyopathies form a heterogeneous group of disorders characterized by structural and electrical abnormalities of the heart muscle, commonly due to a gene variant of the myocardial cell structure. Mostly inherited as a dominant or occasionally recessive trait, they might be part of a syndromic disorder of underlying metabolic or neuromuscular defects or combine early developing extracardiac abnormalities (i.e., Naxos disease). The annual incidence of 1 per 100,000 children appears higher during the first two years of life. Dilated and hypertrophic cardiomyopathy phenotypes share an incidence of 60% and 25%, respectively. Arrhythmogenic right ventricular cardiomyopathy (ARVC), restrictive cardiomyopathy, and left ventricular noncompaction are less commonly diagnosed. Adverse events such as severe heart failure, heart transplantation, or death usually appear early after the initial presentation. In ARVC patients, high-intensity aerobic exercise has been associated with worse clinical outcomes and increased penetrance in at-risk genotype-positive relatives. Acute myocarditis in children has an incidence of 1.4-2.1 cases/per 100,000 children per year, with a 6-14% mortality rate during the acute phase. A genetic defect is considered responsible for the progression to dilated cardiomyopathy phenotype. Similarly, a dilated or arrhythmogenic cardiomyopathy phenotype might emerge with an episode of acute myocarditis in childhood or adolescence. This review provides an overview of childhood cardiomyopathies focusing on clinical presentation, outcome, and pathology.

Indications and management of implantable cardioverter-defibrillator therapy in childhood hypertrophic cardiomyopathy

Sudden cardiac death is the most common mode of death during childhood and adolescence in hypertrophic cardiomyopathy, and identifying those individuals at highest risk is a major aspect of clinical care. The mainstay of preventative therapy is the implantable cardioverter-defibrillator, which has been shown to be effective at terminating malignant ventricular arrhythmias in children with hypertrophic cardiomyopathy but can be associated with substantial morbidity. Accurate identification of those children at highest risk who would benefit most from implantable cardioverter-defibrillator implantation while minimising the risk of complications is, therefore, essential. This position statement, on behalf of the Association for European Paediatric and Congenital Cardiology (AEPC), reviews the currently available data on established and proposed risk factors for sudden cardiac death in childhood-onset hypertrophic cardiomyopathy and current approaches for risk stratification in this population. It also provides guidance on identification of individuals at risk of sudden cardiac death and optimal management of implantable cardioverter-defibrillators in children and adolescents with hypertrophic cardiomyopathy.

Endogenous assessment of late gadolinium enhancement grey zone in patients with non-ischaemic cardiomyopathy with T1ρ and native T1 mapping

AIMS

This study aims to validate and compare the feasibility of T1ρ and native longitudinal relaxation time (T1) mapping in detection of myocardial fibrosis in patients with non-ischaemic cardiomyopathy, focusing on the performance of both methods in identifying late gadolinium enhancement (LGE) grey zone.

METHODS AND RESULTS

Twenty-seven hypertrophic cardiomyopathy (HCM) patients, 16 idiopathic dilated cardiomyopathy (DCM) patients, and 18 healthy controls were prospectively enrolled for native T1 and T1ρ mapping imaging and then all the patients underwent enhancement scan for LGE extent and extracellular volume (ECV) values. In LGE positive patients, the LGE areas were divided into LGE core (6 SDs above remote myocardium) and grey zone (2-6 SDs above remote myocardium) according to the signal intensity of LGE. Both HCM and DCM patients showed significantly higher native T1 values and T1ρ values than controls no matter the presence of LGE (all P < 0.01). There were significant differences in native T1 and T1ρ values among four different types of myocardia (LGE core, grey zone, remote area and control, P < 0.0001). However, the T1ρ values of grey zone were significantly higher than control (P < 0.01), while the native T1 values were not (P = 0.089). T1ρ values were significantly associated with both native T1 values (r = 0.54, P < 0.001) and ECV values (r = 0.54, P < 0.001).

CONCLUSION

T1ρ mapping is a feasible method to detect myocardial fibrosis in patients with non-ischaemic cardiomyopathy no matter the presence of LGE. Compared with native T1, T1ρ may serve as a better discriminator in the identification of LGE grey zone.

Sudden cardiac death in childhood hypertrophic cardiomyopathy

The most prevalent cause of mortality in children with hypertrophic cardiomyopathy (HCM) is sudden cardiac death (SCD), which happens more frequently than in adult patients. Risk stratification tactics have generally been drawn from adult practice, however emerging data has revealed significant disparities between children and adult cohorts, implying the need for pediatric-specific risk stratification methodologies. We conducted an all-language literature search on Medline, Cochrane, Embase, and Google Scholar until October 2021. The following search strings and Medical Subject Heading (MeSH) terms were used: "HCM," "SCD," "Sudden Cardiac Death," and "Childhood Onset HCM." We explored the literature on the risk of SCD in HCM for its epidemiology, pathophysiology, the role of various genes and their influence, associated complications leading to SCD and preventive and treatment modalities. Childhood-onset HCM is linked to significant life-long morbidity and mortality, including a higher SCD rate in children than in adults. The present focus is on symptom relief and avoiding illness-related consequences, but the prospect of future disease-modifying medicines offers an intriguing opportunity to alter disease expression and outcomes in these young individuals. Current preventive recommendations promote implantable cardioverter defibrillator placement based on cumulative risk factor thresholds, although they have been demonstrated to have weak discriminating capacity. This article addresses questions and discusses the etiology, risk factors, and method to risk stratification for SCD in children with HCM.

Myocardial late gadolinium enhancement using delayed 3D IR-FLASH in the pediatric population: feasibility and diagnostic performance compared to single-shot PSIR-bSSFP

BACKGROUND

This study compares three-dimensional (3D) high-resolution (HR) late gadolinium enhancement (LGE; 3D HR-LGE) imaging using a respiratory navigated, electrocardiographically-gated inversion recovery gradient echo sequence with conventional LGE imaging using a single-shot phase-sensitive inversion recovery (PSIR) balanced steady-state free precession (bSSFP; PSIR-bSSFP) sequence for routine clinical use in the pediatric population.

METHODS

Pediatric patients (0-18 years) who underwent clinical cardiovascular magnetic resonance (CMR) with both 3D HR-LGE and single-shot PSIR-bSSFP LGE between January 2018 and June 2020 were included. Image quality (0-4) and detection of LGE in the left ventricle (LV) (per 17 segments), in the right ventricle (RV) (per 3 segments), as endocardial fibroelastosis (EFE), at the hinge points, and at the papillary muscles was analyzed by two blinded readers for each sequence. Ratios of the mean signal intensity of LGE to normal myocardium (LGE:Myo) and to LV blood pool (LGE:Blood) were recorded. Data is presented as median (1st-3rd quartiles). Wilcoxon signed rank test and chi-square analyses were used as appropriate. Inter-rater agreement was analyzed using weighted κ-statistics.

RESULTS

102 patients were included with median age at CMR of 8 (1-13) years-old and 44% of exams performed under general anesthesia. LGE was detected in 55% of cases. 3D HR LGE compared to single-shot PSIR-bSSFP had longer scan time [4:30 (3:35-5:34) vs 1:11 (0:47-1:32) minutes, p < 0.001], higher image quality ratings [3 (3-4) vs 2 (2-3), p < 0.001], higher LGE:Myo [23.7 (16.9-31.2) vs 5.0 (2.9-9.0), p < 0.001], detected more segments of LGE in both the LV [4 (2-8) vs 3 (1-7), p = 0.045] and RV [1 (1-1) vs 1 (0-1), p < 0.001], and also detected more cases of LGE with 13/56 (23%) of patients with LGE only detectable by 3D HR LGE (p < 0.001). 3D HR LGE specifically detected a greater proportion of RV LGE (27/27 vs 17/27, p < 0.001), EFE (11/11 vs 5/11, p = 0.004), and papillary muscle LGE (14/15 vs 4/15, p < 0.001). Inter-rater agreement for the recorded variables ranged from 0.42 to 1.00.

CONCLUSIONS

3D HR LGE achieves greater image quality and detects more LGE than conventional single-shot PSIR-bSSFP LGE imaging, and should be considered an alternative to conventional LGE sequences for routine clinical use in the pediatric population.

Cardiovascular Imaging in China: Yesterday, Today, and Tomorrow

The high prevalence and mortality of cardiovascular diseases in China's large population has increased the use of cardiovascular imaging for the assessment of conditions in recent years. In this study, we review the past 20 years of cardiovascular imaging in China, the increasingly important role played by cardiovascular computed tomography in coronary artery disease and pulmonary embolism assessment, magnetic resonance imaging's use for cardiomyopathy assessment, the development and application of artificial intelligence in cardiovascular imaging, and the future of Chinese cardiovascular imaging.

Ablation of lysophosphatidic acid receptor 1 attenuates hypertrophic cardiomyopathy in a mouse model

Myocardial fibrosis is a key pathologic feature of hypertrophic cardiomyopathy (HCM). However, the fibrotic pathways activated by HCM-causing sarcomere protein gene mutations are poorly defined. Because lysophosphatidic acid is a mediator of fibrosis in multiple organs and diseases, we tested the role of the lysophosphatidic acid pathway in HCM. Lysphosphatidic acid receptor 1 (LPAR1), a cell surface receptor, is required for lysophosphatidic acid mediation of fibrosis. We bred HCM mice carrying a pathogenic myosin heavy-chain variant (403+/-) with Lpar1-ablated mice to create mice carrying both genetic changes (403+/- LPAR1 -/-) and assessed development of cardiac hypertrophy and fibrosis. Compared with 403+/- LPAR1WT, 403+/- LPAR1 -/- mice developed significantly less hypertrophy and fibrosis. Single-nucleus RNA sequencing of left ventricular tissue demonstrated that Lpar1 was predominantly expressed by lymphatic endothelial cells (LECs) and cardiac fibroblasts. Lpar1 ablation reduced the population of LECs, confirmed by immunofluorescence staining of the LEC markers Lyve1 and Ccl21a and, by in situ hybridization, for Reln and Ccl21a. Lpar1 ablation also altered the distribution of fibroblast cell states. FB1 and FB2 fibroblasts decreased while FB0 and FB3 fibroblasts increased. Our findings indicate that Lpar1 is expressed predominantly by LECs and fibroblasts in the heart and is required for development of hypertrophy and fibrosis in an HCM mouse model. LPAR1 antagonism, including agents in clinical trials for other fibrotic diseases, may be beneficial for HCM.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the use of cardiovascular magnetic resonance in pediatric congenital and acquired heart disease : Endorsed by The American Heart Association

Cardiovascular magnetic resonance (CMR) has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of CMR in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of CMR in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Prognostic factors in hypertrophic cardiomyopathy in children: An MRI based study

BACKGROUND

Clinical and prognostic role of cardiac magnetic resonance (CMR) in adult population with hypertrophic cardiomyopathy (HCM) have been largely assessed. We sought to investigate the role of CMR for predicting cardiovascular events in children with HCM.

METHODS

CMR was performed in 116 patients with HCM (37 sarcomeric mutations, 31 other mutations, mean age 10.4 ± 4.3 yrs). CMR protocol included cine imaging for evaluation of morphology and function and late gadolinium enhancement (LGE). Hard cardiac events (sustained VT, resuscitated cardiac arrest, sudden cardiac death, end-stage heart failure, heart transplant and appropriate ICD intervention) were recorded through a median follow-up of 4 (1-7) years.

RESULTS

During follow-up 21 heart cardiac events occurred. At maximal-rank statistic the optimal cut-point for LGE extent for predicting events was ≥2%. Syncope, non-sustained ventricular tachycardia (NSVT) and LGE extent ≥2% were independent predictors of events. At Harrel's C statistic combination of LGE extent ≥2% and syncope was the strongest model for predicting events. HR of patients with LGE extent ≥2% and no history of syncope was 3.6 (1.1-12.2) that increased to 37.6 (5.4-161) in those with LGE extent ≥2% and syncope. The median time dependent AUC of LGE extent (0.88, 95% CI 0.86-0.89) was significantly higher than that of syncope (0.63, 95% CI 0.61-0.66, p < 0.0001) and NSVT (0.52, 95% CI 0.50-0.53, p < 0.0001).

CONCLUSIONS

In children with HCM, LGE and syncope were independent predictors of hard cardiac events at follow-up.

Right ventricular function declines prior to left ventricular ejection fraction in hypertrophic cardiomyopathy

BACKGROUND

The right ventricle (RV) in hypertrophic cardiomyopathy (HCM) tends to be neglected, as previous efforts have predominantly focused on examining the prognostic value of left ventricular (LV) abnormalities. The objectives of this study were to assess RV function in HCM, changes over time, and association with clinical outcomes.

METHODS

Two hundred and ninety HCM patients with preserved LV ejection fraction (LVEF ≥ 55%) and 30 age- and sex-matched controls underwent cardiovascular magnetic resonance (CMR). All patients were followed up for clinical events for a median duration of 4.4 years. Sixty-three patients had a follow-up CMR undertaken at a median interval of 5.4 years. Main study measures and outcomes were RV function (RV ejection fraction (RVEF) and RV strain) at baseline, temporal changes in RV function over time and prognostic value of RV dysfunction for predicting cardiovascular outcomes in HCM.

RESULTS

When compared to controls, HCM patients exhibited lower RV and LV peak global longitudinal systolic strains on feature-tracking analysis of cine images, while RVEF and LVEF were within the normal range. On follow-up CMR, both RV and LV strain parameters decreased over time. RVEF decreased at follow-up (65 ± 7% to 62 ± 7%, P < 0.001) but the change in LVEF was not significant (68 ± 10% to 66 ± 8%, P = 0.30). On clinical follow up, reduced RVEF was an independent predictor of non-sustained ventricular tachycardia (NSVT) [HR 1.10 (95% CI 1.06-1.15), P < 0.001] and composite cardiovascular events (NSVT, stroke, heart failure hospitalisation and cardiovascular death) [HR 1.07 (95% CI 1.03-1.10), P < 0.001]. RV longitudinal strain was an independent predictor of NSVT [HR 1.05 (95% CI 1.01-1.09), P = 0.029]. Patients with RVEF < 55% showed an increased risk of NSVT and composite cardiovascular events. In contrast, LVEF and LV global longitudinal strain were not predictive of such events on multivariable analysis.

CONCLUSIONS

In HCM, RV function, including RV strain, and LV strain decrease over time despite preserved LVEF. Reduction in RV but not LV function is associated with adverse cardiovascular outcomes. Assessing RV function in early HCM disease might have a role in risk stratification to prevent future cardiovascular events.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the Use of Cardiac Magnetic Resonance in Pediatric Congenital and Acquired Heart Disease: Endorsed by The American Heart Association

Cardiovascular magnetic resonance has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of cardiovascular magnetic resonance in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of cardiovascular magnetic resonance in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Differential Diagnosis of Thick Myocardium according to Histologic Features Revealed by Multiparametric Cardiac Magnetic Resonance Imaging

Left ventricular (LV) wall thickening, or LV hypertrophy (LVH), is common and occurs in diverse conditions including hypertrophic cardiomyopathy (HCM), hypertensive heart disease, aortic valve stenosis, lysosomal storage disorders, cardiac amyloidosis, mitochondrial cardiomyopathy, sarcoidosis and athlete's heart. Cardiac magnetic resonance (CMR) imaging provides various tissue contrasts and characteristics that reflect histological changes in the myocardium, such as cellular hypertrophy, cardiomyocyte disarray, interstitial fibrosis, extracellular accumulation of insoluble proteins, intracellular accumulation of fat, and intracellular vacuolar changes. Therefore, CMR imaging may be beneficial in establishing a differential diagnosis of LVH. Although various diseases share LV wall thickening as a common feature, the histologic changes that underscore each disease are distinct. This review focuses on CMR multiparametric myocardial analysis, which may provide clues for the differentiation of thickened myocardium based on the histologic features of HCM and its phenocopies.

What Aspects of Phenotype Determine Risk for Sudden Cardiac Death in Pediatric Hypertrophic Cardiomyopathy?

Sudden cardiac death due to hypertrophic cardiomyopathy (HCM), is the most common autopsy-proven cause of unexpected medical death in children after infancy. This mode of death is preventable by implantation of an internal cardiac defibrillator (ICD), a procedure that has considerable morbidity in childhood patients, and even mortality. Since HCM is an inheritable disease (usually autosomal dominant, occasionally recessive), family screening may identify subjects at risk. This review summarizes published studies carried out to identify which phenotypic markers are important risk factors in childhood patients with HCM and reviews the performance of existing risk-stratification algorithms (HCM Risk-Kids, PRIMaCY) against those of single phenotypic markers. A significant proportion of HCM-patients diagnosed in childhood are associated with RASopathies such as Noonan syndrome, but a knowledge gap exists over risk stratification in this patient group. In conclusion, pediatric risk-stratification algorithms for sudden cardiac death perform better in children than adult HCM risk-stratification strategies. However, current multivariable algorithms overestimate risk substantially without having high sensitivity, and remain ‘a work in progress’. To include additional phenotypic parameters that can be reproducibly measured such as ECG-markers, e.g., ECG risk score (which has high sensitivity and negative predictive value), tissue Doppler diastolic function measurements, and quantification of myocardial scarring on cardiac magnetic resonance imaging, has the potential to improve risk-stratification algorithms. Until that work has been achieved, these are three factors that the clinician can combine with the current algorithm-calculated per cent risk, in order better to assess risk.

A Comprehensive Assessment of Cardiomyopathies through Cardiovascular Magnetic Resonance: Focus on the Pediatric Population

Cardiomyopathies (CMPs) are a heterogeneous group of diseases that involve the myocardium and result in systolic or diastolic impairment of the cardiac muscle, potentially leading to heart failure, malignant arrhythmias, or sudden cardiac death. Occurrence in pediatric age is rare but has been associated with worse outcomes. Non-invasive cardiac imaging techniques, integrated with clinical, genetic, and electrocardiographic data, have shown a pivotal role in the clinical work-up of such diseases by defining structural alterations and assessing potential complications. Above all modalities, cardiovascular magnetic resonance (CMR) has emerged as a powerful tool complementary to echocardiography to confirm diagnosis, provide prognostic information and guide therapeutic strategies secondary to its high spatial and temporal resolution, lack of ionizing radiation, and good reproducibility. Moreover, CMR can provide in vivo tissue characterization of the myocardial tissue aiding the identification of structural pathologic changes such as replacement or diffuse fibrosis, which are predictors of worse outcomes. Large prospective randomized studies are needed for further validation of CMR in the context of childhood CMPs. This review aims to highlight the role of advanced imaging with CMR in CMPs with particular reference to the dilated, hypertrophic and non-compacted phenotypes, which are more commonly seen in children.

Hypertrophic obstructive cardiomyopathy complicated with acute myocardial infarction and diffuse fibrosis: surgery or not?

Background

Hypertrophic cardiomyopathy with extreme hypertrophy, biventricular obstruction and diffuse myocardial fibrosis complicated by myocardial infarction in the absence of obstructive coronary artery disease (MINOCA) is a rare phenotype. Evidence and guideline recommendations are still lacking for a treatment strategy.

Case presentation

Emergency coronary angiography was performed in a 38-year-old man with a 2-year history of nonobstructive hypertrophic cardiomyopathy (HCM) presenting with acute myocardial infarction. The coronary angiogram yielded no stenotic lesions but showed a diffusely dilated left descending artery with slow blood flow. All evidence from biomarker analysis, electrocardiography, echocardiography, and imaging supported the diagnosis of acute myocardial infarction in the left ventricular anterior wall. The echocardiogram demonstrated severe interventricular and apical hypertrophy, severe left ventricular outflow tract obstruction and mild right ventricular outflow tract obstruction. Cardiac magnetic resonance imaging showed a concentric morphological subtype of HCM with diffuse late gadolinium enhancement in the left ventricle. Extended septal myectomy was performed 1 month later, and the patient recovered well.

Conclusions

Hypertrophic obstructive cardiomyopathy with acute myocardial infarction is an indication for coronary angiography. Septal reduction surgery could be performed cautiously in HCM patients with extreme hypertrophy, biventricular obstruction and diffuse myocardial fibrosis complicated by MINOCA to improve the patient’s symptoms.

External validation of the HCM Risk-Kids model for predicting sudden cardiac death in childhood hypertrophic cardiomyopathy

AIMS

Sudden cardiac death (SCD) is the most common mode of death in childhood hypertrophic cardiomyopathy (HCM). The newly developed HCM Risk-Kids model provides clinicians with individualized estimates of risk. The aim of this study was to externally validate the model in a large independent, multi-centre patient cohort.

METHODS AND RESULTS

A retrospective, longitudinal cohort of 421 patients diagnosed with HCM aged 1-16 years independent of the HCM Risk-Kids development and internal validation cohort was studied. Data on HCM Risk-Kids predictor variables (unexplained syncope, non-sustained ventricular tachycardia, maximal left ventricular wall thickness, left atrial diameter, and left ventricular outflow tract gradient) were collected from the time of baseline clinical evaluation. The performance of the HCM Risk-Kids model in predicting risk at 5 years was assessed. Twenty-three patients (5.4%) met the SCD end-point within 5 years, with an overall incidence rate of 2.03 per 100 patient-years [95% confidence interval (CI) 1.48-2.78]. Model validation showed a Harrell's C-index of 0.745 (95% CI 0.52-0.97) and Uno's C-index 0.714 (95% 0.58-0.85) with a calibration slope of 1.15 (95% 0.51-1.80). A 5-year predicted risk threshold of ≥6% identified 17 (73.9%) SCD events with a corresponding C-statistic of 0.702 (95% CI 0.60-0.81).

CONCLUSIONS

This study reports the first external validation of the HCM Risk-Kids model in a large and geographically diverse patient population. A 5-year predicted risk of ≥6% identified over 70% of events, confirming that HCM Risk-Kids provides a method for individualized risk predictions and shared decision-making in children with HCM.

Pediatric Hypertrophic Cardiomyopathy: Exploring the Genotype-Phenotype Association

Pediatric hypertrophic cardiomyopathy (HCM) is the most common form of cardiomyopathy in children and a leading cause of sudden cardiac death. Yet, the association between genotype variation, phenotype expression, and adverse events in pediatric HCM has not been fully elucidated. Although the literature on this topic is evolving in adult HCM, the evidence in children is lacking. Solidifying our understanding of this relationship could improve risk stratification as well as improve our comprehension of the underlying pathophysiological characteristics of pediatric HCM. In this state-of-the-art review, we examine the current literature on genetic variations in HCM and their association with outcomes in children, discuss the current approaches to identifying cardiovascular phenotypes in pediatric HCM, and explore possible avenues that could improve sudden cardiac death risk assessment.

Reduced myocardial septal function assessed by cardiac magnetic resonance feature tracking in patients with hypertrophic obstructive cardiomyopathy: associated with histological myocardial fibrosis and ventricular arrhythmias

AIMS

Echocardiographic studies suggest that strain is related to myocardial fibrosis (MF) and ventricular arrhythmias (VA) in hypertrophic cardiomyopathy (HCM) patients. Cardiac magnetic resonance feature tracking (CMR-FT) also allows strain analysis, but little is known whether it provides incremental value to late gadolinium enhancement imaging (LGE). This study aimed to explore the relationship between CMR-FT-derived strain parameters and histopathology MF and VA and its incremental value to LGE in obstructive HCM (HOCM) patients undergoing septal myectomy.

METHODS AND RESULTS

One hundred and twenty-three symptomatic HOCM patients underwent CMR examination, followed by septal myectomy. The abnormally increased histological MF was defined as higher than the mean + 2 standard deviation (SD) of nine control autopsy subjects who had no history of cardiovascular disease. Septal strain parameters and septal LGE were evaluated at the site of surgical myectomy. Among HOCM patients without LGE, septal circumferential (P = 0.003), longitudinal (P = 0.001), and radial (P = 0.02) strains were significantly impaired in patients with increased histological MF than those without. Histological MF was significantly associated with septal circumferential strain (r = 0.32, P < 0.001), septal longitudinal strain (r = 0.42, P < 0.001), and septal radial strain (r = -0.27, P = 0.003). On multivariate analysis, septal longitudinal strain was independently associated with histological MF [β, 0.19 (0.05-0.34); P = 0.01], and VA [odds ratio, 1.10 (1.01-1.19); P = 0.02]. Moreover, septal longitudinal strain was incremental to septal %LGE in detecting increased MF (P = 0.001) and VA (P = 0.048).

CONCLUSIONS

Septal longitudinal strain at CMR is independently related to histological MF and occurrence of VA in HOCM patients. Moreover, it provides incremental value over LGE in detecting increased MF and VA.