Historical trends in reported survival rates in patients with hypertrophic cardiomyopathy

Arrhythmogenesis in Fabry Disease

PURPOSE OF REVIEW

Fabry Disease (FD) is a rare lysosomal storage disorder characterised by multiorgan accumulation of glycosphingolipid due to deficiency in the enzyme α-galactosidase A. Cardiac sphingolipid accumulation triggers various types of arrhythmias, predominantly ventricular arrhythmia, bradyarrhythmia, and atrial fibrillation. Arrhythmia is likely the primary contributor to FD mortality with sudden cardiac death, the most frequent cardiac mode of death. Traditionally FD was seen as a storage cardiomyopathy triggering left ventricular hypertrophy, diastolic dysfunction, and ultimately, systolic dysfunction in advanced disease. The purpose of this review is to outline the current evidence exploring novel mechanisms underlying the arrhythmia substrate.

RECENT FINDINGS

There is growing evidence that FD cardiomyopathy is a primary arrhythmic disease with each stage of cardiomyopathy (accumulation, hypertrophy, inflammation, and fibrosis) contributing to the arrhythmia substrate via various intracellular, extracellular, and environmental mechanisms. It is therefore important to understand how these mechanisms contribute to an individual's risk of arrhythmia in FD. In this review, we outline the epidemiology of arrhythmia, pathophysiology of arrhythmogenesis, risk stratification, and cardiac therapy in FD. We explore how advances in conventional cardiac investigations performed in FD patients including 12-lead electrocardiography, transthoracic echocardiography, and cardiac magnetic resonance imaging have enabled early detection of pro-arrhythmic substrate. This has allowed for appropriate risk stratification of FD patients. This paves the way for future work exploring the development of therapeutic initiatives and risk prediction models to reduce the burden of arrhythmia.

Trans-Atlantic Differences in Approach to Sudden Death Prevention in Patients With Hypertrophic Cardiomyopathy

The American approach to predicting sudden cardiac death (SCD) in patients with hypertrophic cardiomyopathy diverges from the European method in that it relies on major risk factors independently justifying the implantation of an implantable cardioverter-defibrillator for primary prevention, whereas the European approach uses a mathematical equation to estimate a 5-year risk percentage. The aim of this review is to outline the differences between the American and European guidelines and to show how they have arisen. Furthermore, it will provide insight into the future of SCD risk prediction in patients with hypertrophic cardiomyopathy. The American SCD risk prediction method has high sensitivity but limited specificity, whereas the European method has the opposite. These differences in sensitivity and specificity likely contribute to the fact that primary prevention implantable cardioverter-defibrillator utilization is twofold higher in the United States. It is highly likely that new insights and new imaging modalities will enhance prediction models in the near future. Genotyping could potentially assume a significant role. Left ventricular global longitudinal strain was recently shown to be an independent predictor of SCD. Furthermore, after late gadolinium enhancement, additional cardiac magnetic resonance techniques such as T1 mapping and diffusion tensor imaging are showing encouraging outcomes in predicting SCD. Ultimately, it is conceivable that integrating diverse morphological and genetic characteristics through deep learning will yield novel insights and enhance SCD prediction methods.

An Artificial Intelligence Analysis of Electrocardiograms for the Clinical Diagnosis of Cardiovascular Diseases: A Narrative Review

Artificial intelligence (AI) applied to cardiovascular disease (CVD) is enjoying great success in the field of scientific research. Electrocardiograms (ECGs) are the cornerstone form of examination in cardiology and are the most widely used diagnostic tool because they are widely available, inexpensive, and fast. Applications of AI to ECGs, especially deep learning (DL) methods using convolutional neural networks (CNNs), have been developed in many fields of cardiology in recent years. Deep learning methods provide valuable support for rapid ECG interpretation, demonstrating a diagnostic capability overlapping with specialists in the diagnosis of CVD by a classical analysis of macroscopic changes in the ECG trace. Through photoplethysmography, wearable devices can obtain single-derivative ECGs for the recognition of AI-diagnosed arrhythmias. In addition, CNNs have been developed that recognize no macroscopic electrocardiographic changes and can predict, from a 12-lead ECG, atrial fibrillation, even from sinus rhythm; left and right ventricular function; hypertrophic cardiomyopathy; acute coronary syndromes; or aortic stenosis. The fields of application are many, but numerous are the limitations, mainly associated with the reliability of the acquired data, an inability to verify black box processes, and medico-legal and ethical problems. The challenge of modern medicine is to recognize the limitations of AI and overcome them.

Complications of Implantable Cardioverter Defibrillator and Their Potential Risk Factors in Patients with Hypertrophic Cardiomyopathy

Background

Hypertrophic cardiomyopathy (HCM) has different complications such as cardiac arrhythmia and sudden cardiac death (SCD). Insertion of an implantable cardioverter defibrillator (ICD) is recommended for HCM patients who are at high risk of SCD and malignant arrhythmias, despite having their own potential complications. Hypothesis. We aimed to investigate the prevalence of different complications of ICD insertion and the impact of the potential influential baseline characteristics in a one-year follow-up period.

Methods

This was a retrospective study with a total of 71 HCM patients with ICD insertion. We evaluated the prevalence of different complications of ICD implantation and the impact of baseline characteristics on the occurrence of ICD complications using multivariate regression analysis in three 4-month periods.

Results

In a one-year follow-up, 13 patients (18.3%) experienced at least one of the complications including pneumothorax, lead failure, ICD infection, inappropriate shocks, perforation, and upper limb deep vein thrombosis (DVT) with no mortality. Inappropriate shocks were reported as the most common (11.3%) complication during this period, with a gradual increase in the second (4.2%) and third (5.6%) follow-up sessions. Among all of the baseline characteristics that were investigated in this study, a positive history of hypertension was the only risk factor with significant impact on the occurrence of complications (P = 0.01).

Conclusion

We demonstrated the occurrence of complications during a one-year follow-up as 18.3% in HCM patients with ICD insertion. A positive history of hypertension was the only baseline characteristic affecting the occurrence of complications, and inappropriate shocks were the most common complication.

Validation of the Risk Stratification for Sudden Cardiac Death in Chinese Patients With Hypertrophic Cardiomyopathy

Accurate identification of hypertrophic cardiomyopathy (HCM) patients at high risk of sudden cardiac death (SCD) event is challenging. The objective of this study was to validate the three SCD risk stratifications recommended by the 2014 European Society of Cardiology (ESC) guideline, the 2020 American Heart Association /American College of Cardiology (AHA/ACC) guideline, and the 2022 ESC guideline in Chinese patients with HCM. Our study population are made up of a cohort of 856 HCM patients without prior SCD events. The endpoint was defined as SCD or equivalent events (successful resuscitation after cardiac arrest or appropriate ICD shock for ventricular tachycardia or ventricular fibrillation). During a median follow-up of 43 months, SCD endpoints occurred in 44 (5.1%) patients. A total of 34 (77.3%) patients suffering from SCD events were classified correctly into high-risk groups by the 2020 AHA/ACC guideline, 27(61.4%) by the 2022 ESC guideline, and 13 (29.6%) by the 2014 ESC guideline. The C-statistic of the 2020 AHA/ACC guideline was 0.68 (95% CI, 0.60-0.76), which performed better than the 2022 ESC guideline (0.65: 95% CI, 0.56-0.73), and the 2014 ESC guideline (0.58: 95% CI, 0.48-0.67). The 2020 AHA/ACC guideline displayed better discrimination for SCD risk stratification in Chinese HCM patients than the other two guidelines, with a higher sensitivity but lower specificity.

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.

Effect of Mavacamten on Chinese Patients With Symptomatic Obstructive Hypertrophic Cardiomyopathy: The EXPLORER-CN Randomized Clinical Trial

Importance

Mavacamten has shown clinical benefits in global studies for patients with obstructive hypertrophic cardiomyopathy (oHCM), but evidence in the Asian population is lacking.

Objective

To evaluate the safety and efficacy of mavacamten compared with placebo for Chinese patients with symptomatic oHCM.

Design, Setting, and Participants

This phase 3, randomized, double-blind, placebo-controlled clinical trial was conducted at 12 hospitals in China. Between January 4 and August 5, 2022, patients with oHCM and a left ventricular outflow tract (LVOT) gradient of 50 mm Hg or more and New York Heart Association (NYHA) class II or III symptoms were enrolled and received treatment for 30 weeks.

Interventions

Patients were randomized 2:1 to receive mavacamten (starting at 2.5 mg once daily) or placebo for 30 weeks.

Main Outcomes and Measures

The primary end point was change in Valsalva LVOT peak gradient from baseline to week 30. Left ventricular outflow tract gradients and left ventricular ejection fraction (LVEF) were assessed by echocardiography, while left ventricular mass index (LVMI) was determined by cardiac magnetic resonance imaging. Analysis was performed on an intention-to-treat basis.

Results

A total of 81 patients (mean [SD] age, 51.9 [11.9] years; 58 men [71.6%]) were randomized. Mavacamten demonstrated a significant improvement in the primary end point compared with placebo (least-squares mean [LSM] difference, -70.3 mm Hg; 95% CI, -89.6 to -50.9 mm Hg; 1-sided P < .001). Similar trends were demonstrated for resting LVOT peak gradient (LSM difference, -55.0 mm Hg; 95% CI, -69.1 to -40.9 mm Hg). At week 30, more patients receiving mavacamten than placebo achieved a Valsalva LVOT peak gradient less than 30 mm Hg (48.1% [26 of 54] vs 3.7% [1 of 27]), less than 50 mm Hg (59.3% [32 of 54] vs 7.4% [2 of 27]), and NYHA class improvement (59.3% [32 of 54] vs 14.8% [4 of 27]). Greater improvements were also observed with mavacamten regarding the Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (LSM difference, 10.2; 95% CI, 4.4-16.1), N-terminal pro-B-type natriuretic peptide level (proportion of geometric mean ratio, 0.18; 95% CI, 0.13-0.24), high-sensitivity cardiac troponin I level (proportion of geometric mean ratio, 0.34; 95% CI, 0.27-0.42), and LVMI (mean difference, -30.8 g/m2; 95% CI, -41.6 to -20.1 g/m2). Safety and tolerability were similar between mavacamten and placebo. No patients experienced LVEF less than 50%.

Conclusions

Mavacamten significantly improved Valsalva LVOT gradient vs placebo for Chinese patients. All secondary efficacy end points were also improved. Mavacamten was well tolerated with no new safety signals. This study supports the efficacy and safety of mavacamten in diverse populations, including Chinese patients.

Trial Registration

ClinicalTrials.gov Identifier: NCT05174416.

Sudden Death Risk Assessment in Hypertrophic Cardiomyopathy Across the Lifespan: Reconciling the American and European Approaches

Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited cardiac disease. Since the modern description of HCM more than seven decades ago, great focus has been placed on preventing its most catastrophic complication: sudden cardiac death (SCD). Implantable cardioverter-defibrillators (ICD) have been recognized to provide effective prophylactic therapy. Over the years, two leading societies, the European Society of Cardiology (ESC) and the American Heart Association/American College of Cardiology (AHA/ACC), have proposed risk stratification models to assess SCD in adults. European guidelines rely on a risk calculator, the HCM Risk-SCD, while American guidelines propose a stand-alone risk factor approach. Recently, risk prediction models were also developed in the pediatric population. This article reviews the latest recommendations on the risk stratification of SCD in HCM and summarises current indications for ICD use.

Impact of coronary artery revascularization on long-term outcome in hypertrophic cardiomyopathy patients: a nationwide population-based cohort study

Limited data are available on the long-term outcomes in patients with hypertrophic cardiomyopathy (HCM) patients with significant coronary artery disease (CAD) requiring revascularization. We investigated the risk of cardiovascular outcomes in HCM patients who underwent coronary revascularization compared to the control group without HCM. HCM patients aged ≥ 20 years were enrolled from the Korean National Health Insurance Database. Information on the diagnosis and previous medical history was obtained from the claims data. Cardiovascular outcomes were identified during 8-year after coronary revascularization in HCM patients (HCM group) and matched controls without HCM (non-HCM control group). A total of 431 patients in the HCM group and 1968 in the non-HCM control group were analyzed. The risk of all-cause death, cardiovascular death, sudden cardiac death (SCD), ischemic stroke, and hospitalization due to heart failure was significantly higher in the HCM group than in the non-HCM group, with prominent risk increase of cardiovascular death (adjusted hazard ratio [HR] 2.27, 95% confidence interval [CI] 1.63-3.15, P < 0.001) and ischemic stroke (adjusted HR 2.38, 95% CI 1.55-3.64, P < 0.001). Beyond 1-year after revascularization, the HCM group still had a significantly higher risk of cardiovascular death, SCD, and ventricular fibrillation/tachycardia compared to the non-HCM group. Mortality and major cardiovascular outcomes occurred more frequently in HCM patients with significant CAD requiring revascularization, compared to the matched non-HCM control group. Active and regular surveillance for concomitant risk factors and relevant intervention are warranted in HCM patients at increased risk for CAD.

Demographics and Trends of Hypertrophic Cardiomyopathy-Related Mortality in the US, 1999-2020

BACKGROUND

There is limited data on the mortality trends of HCM in the US.

OBJECTIVE

To study the demographics and trends of mortality in patients with HCM.

METHODS

A retrospective cohort analysis was done with mortality data of patients with HCM listed as an underlying cause of death in the US Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research database (CDC-WONDER) from January 1999 to December 2020. The analysis took place in February 2022. First, we measured HCM-related Age-Adjusted Mortality Rate (AAMR) per 100,000 US population stratified by sex, race, ethnicity, and geographic area. We then calculated the Annual Percentage Change (APC) for AAMR for each.

RESULTS

A total of 24,655 HCM-related deaths occurred between 1999 and 2020. The AAMR for HCM-related deaths declined from 0.5/100,000 patients in 1999 to 0.2 in 2020. The APC changes are as follows: -6.8 (95% CI: -11.8 to -1.5) from 2002-2009, -1.23 (95%CI -13.8 to 13.2) from 2009-2014, -6.71 (95%CI -46.2 to 61.7) from 2014-2017 and remained at 2.07 (95%CI -26.1 to 41.1) from 2017-2020. Men had consistently higher AAMR than women. Overall, AAMR in men was 0.4 (95% CI: 0.4-0.5), and in women was 0.3 (95% CI: 0.3-0.3). A similar trend was noticed in men and women over the years, starting from 1999 (AAMR men: 0.7 and women: 0.4) to 2020 (AAMR men: 0.3 and women: 0.2). AAMRs were highest among black or African American patients 0.6 (95% CI: 0.5-0.6), followed by Non-Hispanic and Hispanic white 0.3 (95% CI 0.3-0.3) and Asian or Pacific Islander 0.2 (95% CI 0.2-0.2). There was substantial variation in each region in the US. States such as California, Ohio, Michigan, Oregon, and Wyoming had the highest AAMR. Large metropolitan cities had higher AAMR than non-metropolitan cities.

CONCLUSION

During the study period from 1999 to 2020, HCM-related mortality steadily decreased. The highest AAMR was observed among men, black patients, and residents of metropolitan areas. States such as California, Ohio, Michigan, Oregon, and Wyoming had the highest AAMR.

High-Sensitivity Cardiac Troponin T Elevation in Hypertrophic Cardiomyopathy Is Associated With Ventricular Arrhythmias

OBJECTIVE

To investigate the relationship between high-sensitivity cardiac troponin T (hs-cTnT) levels and sudden cardiac death (SCD) in patients with hypertrophic cardiomyopathy (HCM).

METHODS

A referral HCM population with prospectively obtained hs-cTnT concentration from March 1, 2018, to April 23, 2020, was reviewed. Patients with end-stage renal disease or an abnormal hs-cTnT level not collected in an outpatient protocolled fashion were excluded. The hs-cTnT level was compared with demographic characteristics, comorbidities, conventional HCM-associated SCD risk factors, imaging, exercise testing, and prior cardiac events.

RESULTS

Of 112 included patients, 69 (62%) had an elevated hs-cTnT concentration. The level of hs-cTnT correlated with known risk factors for SCD, including nonsustained ventricular tachycardia (P=.049) and septal thickness (P=.02). When patients were stratified by having a normal vs an elevated hs-cTnT concentration, patients with elevated hs-cTnT concentration were more likely to have experienced an implantable cardioverter-defibrillator discharge for ventricular arrhythmia, ventricular arrhythmia with hemodynamic instability, or cardiac arrest (incidence rate ratio, 2.96; 95% CI, 1.11 to 10.2). When sex-specific hs-cTnT cutoffs were removed, this association was no longer present (incidence rate ratio, 1.50; 95% CI, 0.66 to 3.60).

CONCLUSION

In a protocolized, outpatient HCM population, hs-cTnT elevations were common and were associated with more arrhythmic expressivity of the HCM substrate as indicated by previous ventricular arrhythmias and appropriate implantable cardioverter-defibrillator shocks only when sex-specific hs-cTnT cutoffs were used. Further research should use different hs-cTnT reference values by sex to determine whether an elevated hs-cTnT value is an independent risk factor for SCD in patients with HCM.

Clinical scenarios of hypertrophic cardiomyopathy-related mortality: Relevance of age and stage of disease at presentation

The evolving epidemiology of hypertrophic cardiomyopathy (HCM) has progressively changed our perception of HCM-related mortality. However, recent studies detailing individual causes of death based on age and clinical setting are lacking. Thus, the present study aimed to describe the modes of death in a consecutive cohort of HCM patients based on presenting clinical features and stage of disease.

METHODS

By retrospective analysis of a large HCM cohort, we identified 161 patients with >1 year follow-up who died between 2000 and 2020 and thoroughly investigated their modes of death. HCM stage at presentation was defined as "classic", "adverse remodeling" or "overt dysfunction".

RESULTS

Of the 161 patients, 103 (64%) died of HCM-related causes, whereas 58 (36%) died of non-HCM-related causes. Patients who died of HCM-related causes were younger than those who died of non-HCM related causes. The most common cause of death was heart failure (HF). Sudden cardiac death (SCD) ranked third, after non cardiovascular death, and mostly occurred in young individuals. The proportion of HF related death and SCD per stage of disease was 14% and 27% in "classic", 38% and 21% in "adverse remodeling" and 74% and 10% in "overt dysfunction".

CONCLUSIONS

Most HCM patients die due to complications of their own disease, mainly in the context of HF. While SCD tends to be juvenile, HF related deaths often occur in age groups no longer amenable to cardiac transplant. Modes of death vary with the stage of disease, with SCD becoming less prevalent in more advanced phases, when competitive risk of HF becomes overwhelming.

Long term mortality in patients with hypertrophic cardiomyopathy - A Danish nationwide study

Background

Patients with hypertrophic cardiomyopathy (HCM) are generally regarded as having increased risk of arrhythmia, stroke, heart failure, and sudden cardiac death, but reported mortality rates vary considerably and originate from selected populations.

Study objective

We aimed to investigate the long-term mortality rate in a nationwide cohort of patients with HCM compared to a matched cohort from the general Danish population.

Methods

All patients with a first-time HCM diagnosis in Denmark between January 1, 2007 and December 31, 2018 were identified through nationwide registries. In the main analysis, two visits in an outpatient clinic were required in order to increase specificity. Patients were matched to controls from the background population in a 1:3 ratio based on age, sex, selected comorbidities and date of HCM. Mortalities were compared using Kaplan Meier estimator and multivariable Cox regression models.

Results

We identified 3126 patients with a first-time diagnosis of HCM. 1197 patients had at least two visits in the outpatient clinic (43 % female, median age 63.1 [25th-75th percentile 52.1-72.1] years). All-cause mortality was significantly higher in HCM patients than in matched controls: 10-year probabilities of death were 36.4 % (95 % CI 30.2-43.5 %) for HCM patients and 19.4 % (95 % CI 16.8-22.5 %) for controls. After adjusting for additional comorbidities and medications, a diagnosis with HCM was associated with an increased mortality rate (HR 1.48 (95 % CI 1.18-1.84, p = 0.001)).

Conclusion

Compared to matched controls from the background population, presence of HCM was associated with a significant increase in mortality rate.

Diabetes outcomes in heart failure patients with hypertrophic cardiomyopathy

Aims: We aimed to assess diabetes outcomes in heart failure (HF) patients with hypertrophic cardiomyopathy (HCM). Methods: The National Inpatient Sample database was analyzed to identify records from 2005 to 2015 of patients hospitalized for HF with concomitant HCM. We examined the prevalence of diabetes in those patients, assessed the temporal trend of in-hospital mortality, ventricular fibrillation, atrial fibrillation, and cardiogenic shock and compared diabetes patients to their non-diabetes counterparts. Results: Among patients with HF, 0.26% had HCM, of whom 29.3% had diabetes. Diabetes prevalence increased from 24.8% in 2005 to 32.7% in 2015. The mean age of patients with diabetes decreased from 71 ± 13 to 67.6 ± 14.2 (p < 0.01), but the prevalence of cardiovascular risk factors significantly increased. In-hospital mortality decreased from 4.3% to 3.2% between 2005 and 2015. Interestingly, cardiogenic shock, VF, and AF followed an upward trend. Age (OR = 1.04 [1.03-1.05]), female gender (OR = 1.50 [0.72-0.88]), and cardiovascular risk factors were associated with a higher in-hospital mortality risk in diabetes. Compared to non-diabetes patients, the ones with diabetes were younger and had more comorbidities. Unexpectedly, the adjusted risks of in-hospital mortality (aOR = 0.88 [0.76-0.91]), ventricular fibrillation (aOR = 0.79 [0.71-0.88]) and atrial fibrillation (aOR 0.80 [0.76-0.85]) were lower in patients with diabetes, but not cardiogenic shock (aOR 1.01 [0.80-1.27]). However, the length of stay was higher in patients with diabetes, and so were the total charges per stay. Conclusion: In total, we observed a temporal increase in diabetes prevalence among patients with HF and HCM. However, diabetes was paradoxically associated with lower in-hospital mortality and arrhythmias.

Genomic findings of hypertrophic and dilated cardiomyopathy characterized in a Thai clinical genetics service

Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are the most common referrals in the Inherited Cardiovascular Condition (ICC) Genetics Service. Several issues must be discussed with patients and their families during the genetic consultation session, including the options for genetic testing and cardiovascular surveillance in family members. We developed an ICC registry and performed next-generation-based DNA sequencing for all patients affected by non-syndromic HCM and idiopathic DCM in our joint specialist genetics service. The target gene sequencing panel relied on the Human Phenotype Ontology with 237 genes for HCM (HP:0001639) and 142 genes for DCM (HP:0001644). All subjects were asked to contact their asymptomatic first-degree relatives for genetic counseling regarding their risks and to initiate cardiovascular surveillance and cascade genetic testing. The study was performed from January 1, 2014, to December 31, 2020, and a total of 62 subjects (31-HCM and 31-DCM) were enrolled. The molecular detection frequency was 48.39% (32.26% pathogenic/likely pathogenic, 16.13% variant of uncertain significance or VUS for HCM, and 25.81% (16.13% pathogenic/likely pathogenic, 9.68% VUS) for DCM. The most prevalent gene associated with HCM was MYBPC3. The others identified in this study included ACTN2, MYL2, MYH7, TNNI3, TPM1, and VCL. Among the DCM subjects, variants were detected in two cases with the TTN nonsense variants, while the others were missense and identified in MYH7, DRSP3, MYBPC3, and SCN5A. Following the echocardiogram surveillance and cascade genetic testing in the asymptomatic first-degree relatives, the detection rate of new cases was 8.82% and 6.25% in relatives of HCM and DCM subjects, respectively. Additionally, a new pre-symptomatic relative belonging to an HCM family was identified, although the genomic finding in the affected case was absent. Thus, ICC service is promising for the national healthcare system, aiming to prevent morbidity and mortality in asymptomatic family members.

Symptoms and ECG changes precede sudden cardiac death in hypertrophic cardiomyopathy—A nationwide study among the young in Sweden

Background

Hypertrophic cardiomyopathy (HCM) is a major cause of sudden cardiac death (SCD) in the young. We aimed to characterize detailed family history, symptoms, hospital utilization and ECG changes before SCD.

Methods

We extracted all cases suffering SCD with HCM from the SUDDY cohort, which includes all cases of SCD between 2000–2010 in Sweden among individuals aged 0–35 years along with their controls. We gathered data from mandatory national registries, autopsy reports, medical records, ECGs (including military conscripts), and detailed family history from an interview-based questionnaire (with relatives, post-mortem).

Results

Thirty-eight cases (7 female), mean age 22 years, with HCM were identified. Among these, 71% presented with possible cardiac symptoms (chest pain [26%], syncope [22%], palpitations [37%]), before death; 69% received medical care (vs 21% in controls) within 180 days before death. The majority (68%) died during recreational activity (n = 14) or exercise/competitive sports (n = 12). Fifteen (39%) had a known cardiac disorder prior to death, with HCM being diagnosed pre-mortem in nine cases. 58% presented with abnormal ECG recordings pre-mortem, and 50% had a positive family history (1^st-3^rd generation) for heart disease.

Conclusion

In this comprehensive, nationwide study of SCD due to HCM, 87% (33/38) of cases had one or more abnormality prior to death, including cardiac symptoms, a positive family history, known cardiac disease or ECG abnormalities. They sought medical care prior death, to a larger extent than controls. These findings suggest that cardiac screening should be expanded beyond competitive athletes to aid SCD prevention in the young population with HCM.

Epidemiology of Cardiomyopathy in Taiwanese Population Aged Younger Than 65 Years

BACKGROUND

Few studies have investigated the epidemiology of cardiomyopathy (CMP) in the general population in Taiwan. The aim of this study was to investigate this issue.

METHODS

We identified patients aged < 65 years and diagnosed with CMP between 2001 and 2014 from the National Health Insurance Database of Taiwan 2000-2014. Those with known or presumed causes of CMP were further identified.

RESULTS

We identified 38,868 CMP patients (male/female = 2.13). Half had known or presumed causes of CMP, including coronary artery disease (23.6%), congenital heart disease (1.6%), metabolic disease (8.4%), conduction disturbance/dyssynchrony (2.2%), myocarditis (0.5%), muscular dystrophy (1.42%), Kawasaki disease (0.2%), nutrition problems or alcoholism (2.9%), and unspecified causes (12.4%). The incidence rates of CMP without known causes were 1.13 and 8.70 per 100,000 person-years in pediatric (0-19 years) and adult (20-64 years) populations, respectively. After an initial peak during infancy (9.16 per 100,000 person-years), the incidence declined to a nadir in those aged from 5 to 14 years, and then steadily increased during adulthood (26.51 per 100,000 person-years in those aged 60-64 years). Although mortality was higher in the pediatric (11.4%) than in the adult (1.5%) patients, the proportion of sudden death to all deaths was similar in the pediatric (9.9%) and adult (10.5%) patients.

CONCLUSIONS

This study provides an epidemiological continuum of CMP in a Taiwanese population aged < 65 years. The results revealed an initial peak during infancy, followed by a decline in adolescence and a subsequent steady rise. The prognosis was poorer in the pediatric patients, and poorest in the infants. However, the risk of sudden death was the same in the adult and pediatric patients.

Case report: Double-chambered right ventricle diagnosed in a middle-aged female with hypertrophic cardiomyopathy and atrial flutter: A rare case

Double-chambered right ventricle (DCRV) is a rare congenital heart defect in adults, manifesting with progressive right ventricular outflow tract obstruction. We describe the first case of DCRV coexisting with hypertrophic cardiomyopathy, which is complicated by atrial flutter. A middle-aged woman with recurrent symptomatic atrial flutter who had previously been diagnosed with biventricular hypertrophic cardiomyopathy was admitted to our department. Echocardiography and cardiac magnetic resonance revealed asymmetrical interventricular septal hypertrophy, and abnormal muscle bundles within the right ventricle, generating an obstructive gradient. Genetic testing detected a hypertrophic cardiomyopathy-associated mutation: MYH7, c.4135G &gt; A, p. Ala1379Thr. A diagnosis of DCRV complicated by hypertrophic cardiomyopathy and atrial flutter was made. Surgical intervention was performed, which included radiofrequency ablation, removal of abnormal muscle bundles, and ventricular septal defect repair. Intraoperative transesophageal echocardiography demonstrated the well-corrected right ventricular outflow tract. Free of early postoperative complications, the patient was discharged in sinus rhythm on the 11th day after the surgery. Unfortunately, the patient died from a sudden death 38 days following the surgery. In conclusion, the coexistence of DCRV with hypertrophic cardiomyopathy in patients is an uncommon condition. The present case highlights the importance of diagnostic imaging in the management of this disorder.

Prognostic significance of serum alkaline phosphatase for all-cause mortality in patients with hypertrophic cardiomyopathy: A cohort of the hospitalized population

Higher levels of serum alkaline phosphatase (ALP) as a novel risk factor was recently found associated with mortality in different population, whereas, the relationship remains unknown in hypertrophic cardiomyopathy (HCM) population. In this study, we hypothesized that increased ALP could predict all-cause mortality in the adult HCM population. In this cohort study, retrospective data from 538 HCM patients consecutively recruited in West China Hospital were collected. Patients were divided into two groups by baseline ALP with 80 IU/L as the cutoff. All-cause mortality was set as the endpoint. Subgroup analysis was conducted in patients with normal liver function. In total, 461 adult HCM patients were included. After a median follow-up of 4.7 years, 91 patients died. Alkaline phosphatase was an independent predictor of all-cause mortality since patients in the higher ALP group had an increased risk (adjusted HR 2.0, 95% CI: 1.3-3.3, P < 0.01) compared with those in the lower ALP group. In subgroup analysis, the relationship was consistent with the overall (adjusted HR: 3.0, 95% CI: 1.7-5.3, P < 0.01 for the higher ALP group). In the Chinese cohort study of HCM patients, serum ALP is independently associated with all-cause mortality. Patients with a measured value above 80 IU/L had an increased risk of all-cause mortality and this cutoff might help with risk stratification in HCM population.

Contemporary Diagnosis and Management of Hypertrophic Cardiomyopathy: The Role of Echocardiography and Multimodality Imaging

Hypertrophic cardiomyopathy (HCM) is an underdiagnosed genetic heart disease with an estimated prevalence of 0.2–0.5%. Although the prognosis of HCM is relatively good, with an annual general mortality of ~0.7%, some patients have an increased risk of sudden death, or of developing severe heart failure requiring heart transplantation or left ventricular (LV) assist device therapy. Therefore, earlier diagnosis and proper identification of high-risk patients may reduce disease-related morbidity/mortality by promoting timely treatment. Echocardiography is the primary imaging modality for patients with suspected HCM; it plays central roles in differential diagnosis from other causes of LV hypertrophy and in evaluating morphology, hemodynamic disturbances, LV function, and associated valvular disease. Echocardiography is also an essential tool for the continuous clinical management of patients with confirmed HCM. Other imaging modalities, such as cardiac computed tomography (CT) and cardiac magnetic resonance imaging (MRI), can supplement echocardiography in identifying high-risk as well as milder HCM phenotypes. The role of such multimodality imaging has been steadily expanding along with recent advancements in surgical techniques and minimally invasive procedures, and the emergence of novel pharmacotherapies directly targeting pathogenic molecules such as myosin inhibitors. Here we review essential knowledge surrounding HCM with a specific focus on structural and functional abnormalities assessed by imaging modalities, leading to treatment strategies.

Changing concepts in heart muscle disease: the evolving understanding of hypertrophic cardiomyopathy

Sixty years ago, hypertrophic cardiomyopathy (HCM) was considered a rare lethal disease that affected predominantly young adults and for which there were few treatment options. Today, it is recognised to be a relatively common disorder that presents throughout the life course with a heterogeneous clinical phenotype that can be managed effectively in the majority of individuals. A greater awareness of the condition and less reluctance from healthcare practitioners to make the diagnosis, coupled with improvements in cardiac imaging, including greater use of artificial intelligence and improved yields from screening efforts, have all helped facilitate a more precise and timely diagnosis. This enhanced ability to diagnose HCM early is being paired with innovations in treatment, which means that the majority of patients receiving a contemporary diagnosis of HCM can anticipate a normal life expectancy and expect to maintain a good functional status and quality of life. Indeed, with increasing translation of molecular genetics from bench to bedside associated with a growing number of randomised clinical trials of novel therapies aimed at ameliorating or perhaps even preventing the disease, the next chapter in the story for HCM will provide much excitement and more importantly, offer much anticipated reward for our patients.

Comparison of mortality and cause of death between adults with and without hypertrophic cardiomyopathy

Insufficient evidence is available comparing mortality and cause of death between general hypertrophic cardiomyopathy (HCM) and general non-HCM populations. We aimed to investigate how causes of death and mortality differ in subjects with and without HCM. Using the National Health Insurance Service database from 2009 to 2016, individuals who underwent health check-up(s) with or without a history of HCM were identified. Participants in the HCM group were matched at a 1:1 ratio with those in the non-HCM group using propensity scores calculated from the baseline covariates. Mortality rates and risks were compared between the groups. In total, 14,858 participants (7,429 each in the HCM and non-HCM groups) were followed up over a mean 4.4 ± 2.2 years (mean age, 61.0 years; male proportion, 66.8%). Compared to the non-HCM group, the HCM group showed a higher risk of all-cause and HCM-related mortality and a similar risk for non-cardiovascular mortality (hazard ratio [95% confidence interval] 1.57 [1.38–1.78], 2.71 [1.92–3.83], and 1.04 [0.88–1.23], respectively). The sensitivity analyses consistently showed that the HCM group showed higher risks of all-cause and HCM-related mortality than the non-HCM group. The female participants with HCM were associated with an increasing trend of the risks of all-cause mortality but not HCM-related mortality compared to their male counterparts (p for interaction < 0.001 and 0.185, respectively). In conclusion, compared to the non-HCM population, the general HCM population showed higher risks of both all-cause and HCM-related mortality, but had a similar risk of non-cardiovascular mortality.

Arrhythmic risk stratification in ischemic, non-ischemic and hypertrophic cardiomyopathy: A two-step multifactorial, electrophysiology study inclusive approach

Annual arrhythmic sudden cardiac death ranges from 0.6% to 4% in ischemic cardiomyopathy (ICM), 1% to 2% in non-ischemic cardiomyopathy (NICM), and 1% in hypertrophic cardiomyopathy (HCM). Towards a more effective arrhythmic risk stratification (ARS) we hereby present a two-step ARS with the usage of seven non-invasive risk factors: Late potentials presence (≥ 2/3 positive criteria), premature ventricular contractions (≥ 30/h), non-sustained ventricular tachycardia (≥ 1episode/24 h), abnormal heart rate turbulence (onset ≥ 0% and slope ≤ 2.5 ms) and reduced deceleration capacity (≤ 4.5 ms), abnormal T wave alternans (≥ 65μV), decreased heart rate variability (SDNN < 70ms), and prolonged QT_c interval (> 440 ms in males and > 450 ms in females) which reflect the arrhythmogenic mechanisms for the selection of the intermediate arrhythmic risk patients in the first step. In the second step, these intermediate-risk patients undergo a programmed ventricular stimulation (PVS) for the detection of inducible, truly high-risk ICM and NICM patients, who will benefit from an implantable cardioverter defibrillator. For HCM patients, we also suggest the incorporation of the PVS either for the low HCM Risk-score patients or for the patients with one traditional risk factor in order to improve the inadequate sensitivity of the former and the low specificity of the latter.

Sudden cardiac death in cardiomyopathies: acting upon "acceptable" risk in the personalized medicine era

Patients with cardiomyopathies are confronted with the risk of sudden cardiac death (SCD) throughout their lifetime. Despite the fact that SCD is relatively rare, prognostic stratification is an integral part of physician-patient discussion, with the goal of risk modification and prevention. The current approach is based on a concept of "acceptable risk." However, there are intrinsic problems with an algorithm-based approach to risk management, magnified by the absence of robust evidence underlying clinical decision support tools, which can make high- versus low-risk classifications arbitrary. Strategies aimed at risk reduction range from selecting patients for an implantable cardioverter defibrillator (ICD) to disqualification from competitive sports. These clinical options, especially when implying the use of finite financial resources, are often delivered from the physician's perspective citing decision-making algorithms. When the burden of intervention-related risks or financial costs is deemed higher than an "acceptable risk" of SCD, the patient's perspective may not be appropriately considered. Designating a numeric threshold of "acceptable risk" has ethical implications. One could reasonably ask "acceptable to whom?" In an era when individual choice and autonomy are pillars of the physician-patient relationship, the subjective aspects of perceived risk should be acknowledged and be part of shared decision-making. This is particularly true when the lack of a strong scientific evidence base makes a dichotomous algorithm-driven approach suboptimal for unmitigated translation to clinical practice.

The Role of Cardiovascular Magnetic Resonance Imaging in the Evaluation of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disorder, affecting 1 out of 500 adults globally. It is a widely heterogeneous disorder characterized by a range of phenotypic expressions, and is most often identified by non-invasive imaging that includes echocardiography and cardiovascular magnetic resonance imaging (CMR). Within the last two decades, cardiac magnetic resonance imaging (MRI) has emerged as the defining tool for the characterization and prognostication of cardiomyopathies. With a higher image quality, spatial resolution, and the identification of morphological variants of HCM, CMR has become the gold standard imaging modality in the assessment of HCM. Moreover, it has been crucial in its management, as well as adding prognostic information that clinical history nor other imaging modalities may not provide. This literature review addresses the role and current applications of CMR, its capacity in evaluating HCM, and its limitations.

Prognostic value of regional strain by cardiovascular magnetic resonance feature tracking in hypertrophic cardiomyopathy

BACKGROUND

Few studies have demonstrated the performance of regional strain by cardiovascular magnetic resonance (CMR) feature tracking in hypertrophic cardiomyopathy (HCM) patients, and the prognostic value of segmental strain remains unknown. This study aimed to explore the prognostic implications of strain parameters generated by CMR feature tracking analysis in HCM patients.

METHODS

In total, 104 clinically diagnosed HCM patients and 30 healthy volunteers were enrolled in this study, and all patients underwent a standard CMR examination. Global and regional strain was computed by short axis, 2-, 3-, and 4-chamber view cine MR imaging using specialized software. Cardiac structure, function, and myocardial strain were compared between the control group and HCM patients, and the event and event-free groups. Univariate and multivariate Cox regression analyses were performed to evaluate the correlations between clinical and CMR parameters and poor prognosis.

RESULTS

During the follow-up time, 8 patients reached the primary end points and 14 patients reached secondary end points. Regional radial strain of hypertrophic segments (RRS) and regional circumferential strain of hypertrophic segments (RCS) were worse in HCM patients with primary and secondary end points. In univariate Cox regression analysis of RRS, RCS were associated with primary and secondary end points. Regional radial strain of hypertrophic segments [hazard ratio (HR) 1.64, 95% confidence interval (CI): 1.13-2.38] and RCS (HR 2.35, 95% CI: 1.20-4.59) were independent predictors of primary end points, and RRS (HR 1.71, 95% CI: 1.09-2.66) and RCS (HR 2.63, 95% CI: 1.20-5.75) remained independent predictors of secondary end points in multivariate analysis. Kaplan-Meier survival curves indicated patients with RRS <10.0% and RCS ≥-8.5% had a higher rate of primary end points, and patients with RRS <17.9% and RCS ≥-12.1% experienced a higher rate of secondary end points.

CONCLUSIONS

In HCM patients, RRS and RCS were associated with primary and secondary end points and remained independent predictors in multivariate analysis. Impaired regional strain may potentially predict poor prognosis in HCM patients.

KEYWORDS

Prognosis; hypertrophic cardiomyopathy (HCM); cardiovascular magnetic resonance (CMR); regional strain.

Arrhythmia monitoring for risk stratification in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiomyopathy, presenting significant clinical heterogeneity. Arrhythmia risk stratification and detection are critical components in the evaluation and management of all cases of HCM. The 2020 American Heart Association/American College of Cardiology HCM guidelines provide new recommendations for periodic 24-48-hour ambulatory electrocardiogram monitoring to screen for atrial and ventricular arrhythmias. A strategy of more frequent or prolonged monitoring would lead to earlier arrhythmia recognition and the potential for appropriate treatment. However, whether such a strategy in patients with HCM results in improved outcomes is not yet established. The available evidence, knowledge gaps, and potential merits of such an approach are reviewed. Cardiac implantable electronic devices provide an opportunity for early arrhythmia detection, with the potential to enable early management strategies in order to improve outcomes.

Projecting the Long-term Clinical Value of Mavacamten for the Treatment of Obstructive Hypertrophic Cardiomyopathy in the United States: An Assessment of Net Health Benefit

PURPOSE

The aim of the study was to project the long-term net health benefits of mavacamten for the treatment of symptomatic obstructive hypertrophic cardiomyopathy (HCM) in the United States.

METHODS

A Markov model with 4 mutually exclusive health states (New York Heart Association [NYHA] functional classes I, II, and III/IV and death) was developed to project the life-years (LYs) and quality-adjusted life-years (QALYs) over a lifetime horizon for patients with symptomatic obstructive HCM receiving mavacamten with or without β-blocker (BB) or calcium channel blocker (CCB) monotherapy or placebo with or without BB or CCB monotherapy. The model simulated a patient cohort with a starting age of 59 years and 41% women. Transition probabilities across NYHA functional classes were estimated using data from the Phase III Clinical Study to Evaluate Mavacamten (MYK-461) in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy (EXPLORER-HCM) and the EXPLORER long-term extension (EXPLORER-LTE) cohort from the Long-term Safety Extension Study of Mavacamten in Adults who Have Completed MAVERICK-HCM or EXPLORER-HCM (MAVA-LTE) trial and were extrapolated after week 30. The mortality risks of NYHA functional class I were assumed to be the age- and sex-specific mortality risks of the US general population. The mortality risks for NYHA class II and III/IV were estimated using those for class I in conjunction with the relative mortality risks derived using patients with obstructive HCM from a large real-world registry. Health state utilities for each treatment were estimated from EXPLORER-HCM. Both LYs and QALYs were aggregated over a lifetime for each treatment arm, discounted at 3% annually, and compared between the 2 arms. Sensitivity analyses were conducted to evaluate the robustness of the model findings.

FINDINGS

Over a lifetime, treatment with mavacamten with or without BB or CCB monotherapy was associated with 3.67 incremental LYs compared with placebo with or without BB or CCB monotherapy (13.00 vs 9.33 LYs). Compared with individuals in the placebo group, patients in the mavacamten group were projected to spend 6.17 additional LYs in NYHA functional class I and 0.04 and 2.46 fewer LYs in NYHA functional classes II and III/IV, respectively. With utilities incorporated, mavacamten with or without BB or CCB monotherapy was associated with 4.17 additional QALYs compared with placebo with or without BB or CCB monotherapy (11.74 vs 7.57 QALYs). In the sensitivity analyses, incremental benefits ranged from 1.55 to 6.21 LYs and from 2.48 to 6.19 QALYs across the scenarios.

IMPLICATIONS

This model projected substantial net health benefits associated with mavacamten for symptomatic obstructive HCM owing to improved patient survival and quality of life. The projected QALY gain underscored the likely long-term clinical value of mavacamten in symptomatic obstructive HCM.

Cardiovascular Diseases That Have Emerged From the Darkness

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

Living with hypertrophic cardiomyopathy: a patient's perspective

Hypertrophic cardiomyopathy (HCM) is a complex disease characterized by thickening of the cardiac muscle. Common symptoms include chest pain, shortness of breath, palpitations, fatigue and syncope (fainting), which are often confused for other conditions. Clinical treatment focuses on the relief of symptoms with medical therapies, which provide adequate to more variable symptomatic relief. Patients may experience more severe complications that require surgical intervention, such as implantable cardioverter-defibrillator therapy or septal myectomy. Despite the potential impact on quality of life, the humanistic burden of HCM is not well established. Here, we present four patient testimonials that highlight challenges faced by patients and clinicians in diagnosing HCM and managing symptoms. These testimonials provide valuable information on the spectrum and expression of HCM across generations. Such testimonials can better inform disease diagnosis and monitoring, maximizing quality of life and improving disease outcome.

Lowering the Recommended Maximal Wall Thickness Threshold Improves Diagnostic Sensitivity in Asians With Hypertrophic Cardiomyopathy

Background

Hypertrophic cardiomyopathy (HCM) is defined as left ventricular end-diastolic maximal wall thickness (WT_Max) ≥15.0 mm, without accounting for ethnicity, sex, and body size. It is well-established that Asians have smaller hearts than do Caucasians.

Objectives

This study aims to examine the implications of this single absolute WT_Max threshold on the diagnosis of HCM in Asians.

Methods

The study consisted of 360 healthy volunteers (male: n = 174; age: 50 ± 12 years) and 114 genetically characterized patients with HCM (male: n = 83; age: 52 ± 13 years; genotype-positive, n = 39). All participants underwent cardiovascular magnetic resonance. WT_Max was measured semiautomatically at end-diastole according to the standard 16 myocardial segments.

Results

Healthy male volunteers had increased WT_Max compared with that of female volunteers (8.4 ± 1.2 mm vs 6.6 ± 1.1 mm, respectively; P < 0.001). Conversely, WT_Max was similar between male and female patients with HCM (15.2 ± 3.4 mm vs 14.7 ± 3.0 mm, respectively; P = 0.484) and between those with and without a pathogenic gene variant (P = 0.828). Using the recommended diagnostic threshold of 15.0 mm, 56 patients with HCM had WT_Max <15.0 mm and no healthy volunteers had WT_Max >15.0 mm (specificity of 100% and sensitivity of 51%). Lowering WT_Max thresholds to 10.0 mm in female patients and 12.0 mm in male patients did not affect specificity (100%) but significantly improved sensitivity (84%). Despite lower left ventricular mass, female patients with HCM demonstrated more features of adverse cardiac remodeling than did male patients: increased myocardial fibrosis, higher asymmetric ratio, and disproportionately worse myocardial strain.

Conclusions

The study highlights cautious application of guideline-recommended WT_Max to diagnose HCM in Asians. Lowering WT_Max to account for ethnicity and sex improves diagnostic sensitivity without compromising specificity.

Purkinje triggers of ventricular fibrillation in patients with hypertrophic cardiomyopathy

INTRODUCTION

Ventricular fibrillation (VF) is the main mechanism of sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). The origin of VF and the success of catheter ablation to eliminate recurrent episodes in this population are poorly understood.

METHODS AND RESULTS

From 2010 to 2014, five patients with HCM (age 21 ± 9 years, three female) underwent invasive electrophysiological studies and ablation at our center after resuscitation from recurrent (9 ± 7) episodes of VF. Ventricular premature beats (VPBs), seen to initiate VF in certain cases, were recorded noninvasively before the ablation procedure. Postprocedural computed tomography (CT) was performed to correlate ablation sites with myocardial hypertrophy in three patients. Outcomes were assessed by clinical follow-up and implantable cardioverter-defibrillator interrogations. VPB triggers were localized invasively to the distal left Purkinje conduction system (left posterior fascicle [2], left anterior fascicle [1], and both fascicles [2]). All targeted VF triggers were successfully eliminated by radiofrequency ablation in the left ventricle. Among patients with postablation CT imaging, 93 ± 12% of ablation sites corresponded to hypertrophied segments. Over 50 ± 38 months, four of five patients were free from primary VF without antiarrhythmic drug therapy. One patient who had 13 episodes of VF before ablation had a single recurrence.

CONCLUSION

In our study of patients with HCM and recurrent VF, VF was not initiated from the myocardium but rather from Purkinje arborization. These sources colocalized with the hypertrophic substrate, suggesting electromechanical interaction. Focal ablation at these sites was associated with a marked reduction in VF burden.

Severe right ventricular hypertrophy in hypertrophic cardiomyopathy: Serious symptoms, complex surgical procedures, and poor prognosis in Fuwai Hospital

OBJECTIVE

Severe right ventricular hypertrophy (SRVH) in hypertrophic cardiomyopathy (HCM) is rare. We studied the clinical characteristics and prognosis of 36 patients with HCM and SRVH in a Chinese cohort.

METHODS

Patients with HCM and SRVH were enrolled between 2013 and 2017. The clinical characteristics, treatment therapies, and clinical outcomes of the 36 patients were retrospectively studied and compared with those of 128 patients without SRVH.

RESULTS

Patients in the group with SRVH were younger than those in the group without SRVH (27.58±15.09 years vs 40.34±13.21 years, respectively; p<0.001). Patients with SRVH had more serious clinical symptoms and a higher New York Heart Association functional class than those without SRVH. Most patients in the group with SRVH exhibited diffuse RV hypertrophy, and 13 patients presented with biventricular outflow tract obstruction. Maximal left ventricular (LV) wall thickness (27.29±7.95 mm vs 24.33±5.85 mm, respectively; p=0.027) and LV outflow tract gradient (80.83±24.41 mm Hg vs 42.3±5.7 mm Hg, respectively; p=0.000) were significantly greater in patients with SRVH than in those without SRVH. A total of 30 patients in the group with SRVH underwent surgical correction. During a median follow-up period of 48 months, six patients with SRVH reached primary clinical endpoints (four sudden cardiac deaths, one heart failure-related death, and one heart transplantation), whereas only two deaths occurred in the patients without SRVH.

CONCLUSION

We conclude that patients with HCM and SRVH exhibit serious symptoms and have complex surgical requirements and poor clinical outcomes.

Sudden cardiac death: A comparative review of humans, dogs and cats

Sudden death is one of the most common causes of death in humans in Western countries. Approximately 85% of these cases are of cardiac origin. In dogs and cats, sudden cardiac death (SCD) also commonly occurs, but fewer pathophysiological and prevalence data are available. Both structural, primarily 'electrical' and ischemic heart diseases are known to cause SCD, many of which share similar underlying arrhythmogenic mechanisms between humans and companion animals. As for underlying genetics, numerous mutations on multiple loci have been related to SCD in humans, but only a few mutations associated with dilated cardiomyopathy and SCD have been identified in dogs, e.g. in the phospholamban and titin genes. Information published from human medicine can therefore inform future veterinary studies, but also dogs and cats could act as spontaneous models of SCD in humans. Further research in both fields is therefore warranted to better understand the pathophysiology, genetics, and prevention of SCD.

Translational investigation of electrophysiology in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) patients are at increased risk of ventricular arrhythmias and sudden cardiac death, which can occur even in the absence of structural changes of the heart. HCM mouse models suggest mutations in myofilament components to affect Ca²⁺ homeostasis and thereby favor arrhythmia development. Additionally, some of them show indications of pro-arrhythmic changes in cardiac electrophysiology. In this study, we explored arrhythmia mechanisms in mice carrying a HCM mutation in Mybpc3 (Mybpc3-KI) and tested the translatability of our findings in human engineered heart tissues (EHTs) derived from CRISPR/Cas9-generated homozygous MYBPC3 mutant (MYBPC3hom) in induced pluripotent stem cells (iPSC) and to left ventricular septum samples obtained from HCM patients.

We observed higher arrhythmia susceptibility in contractility measurements of field-stimulated intact cardiomyocytes and ventricular muscle strips as well as in electromyogram recordings of Langendorff-perfused hearts from adult Mybpc3-KI mice than in wild-type (WT) controls. The latter only occurred in homozygous (Hom-KI) but not in heterozygous (Het-KI) mouse hearts. Both Het- and Hom-KI are known to display pro-arrhythmic increased Ca²⁺ myofilament sensitivity as a direct consequence of the mutation. In the electrophysiological characterization of the model, we observed smaller repolarizing K⁺ currents in single cell patch clamp, longer ventricular action potentials in sharp microelectrode recordings and longer ventricular refractory periods in Langendorff-perfused hearts in Hom-KI, but not Het-KI. Interestingly, reduced K⁺ channel subunit transcript levels and prolonged action potentials were already detectable in newborn, pre-hypertrophic Hom-KI mice. Human iPSC-derived MYBPC3hom EHTs, which genetically mimicked the Hom-KI mice, did exhibit lower mutant mRNA and protein levels, lower force, beating frequency and relaxation time, but no significant alteration of the force-Ca²⁺ relation in skinned EHTs. Furthermore, MYBPC3hom EHTs did show higher spontaneous arrhythmic behavior, whereas action potentials measured by sharp microelectrode did not differ to isogenic controls. Action potentials measured in septal myectomy samples did not differ between patients with HCM and patients with aortic stenosis, except for the only sample with a MYBPC3 mutation.

The data demonstrate that increased myofilament Ca²⁺ sensitivity is not sufficient to induce arrhythmias in the Mybpc3-KI mouse model and suggest that reduced K⁺ currents can be a pro-arrhythmic trigger in Hom-KI mice, probably already in early disease stages. However, neither data from EHTs nor from left ventricular samples indicate relevant reduction of K⁺ currents in human HCM. Therefore, our study highlights the species difference between mouse and human and emphasizes the importance of research in human samples and human-like models.

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Sudden cardiac death is threatening hypertrophic cardiomyopathy (HCM) patients.

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Arrhythmia mechanisms are not well understood.

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Mouse HCM models showed relevant reduction in K⁺ currents.

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Human iPSC-EHT model and HCM patient septal myectomies did not display this mechanism.

Prospective follow-up in various subtypes of cardiomyopathies: insights from the ESC EORP Cardiomyopathy Registry

AIMS

The European Society of Cardiology (ESC) European Observational Research Programme (EORP) Cardiomyopathy Registry is a prospective multinational registry of consecutive patients with cardiomyopathies. The objective of this report is to describe the short-term outcomes of adult patients (≥18 years old).

METHODS AND RESULTS

Out of 3208 patients recruited, follow-up data at 1 year were obtained in 2713 patients (84.6%) [1420 with hypertrophic (HCM); 1105 dilated (DCM); 128 arrhythmogenic right ventricular (ARVC); and 60 restrictive (RCM) cardiomyopathies]. Improvement of symptoms (dyspnoea, chest pain, and palpitations) was globally observed over time (P < 0.05 for each). Additional invasive procedures were performed: prophylactic implantation of implantable cardioverter-defibrillator (ICD) (5.2%), pacemaker (1.2%), heart transplant (1.1%), ablation for atrial or ventricular arrhythmia (0.5% and 0.1%). Patients with atrial fibrillation increased from 28.7% to 32.2% of the cohort. Ventricular arrhythmias (VF/ventricular tachycardias) in ICD carriers (primary prevention) at 1 year were more frequent in ARVC, then in DCM, HCM, and RCM (10.3%, 8.2%, 7.5%, and 0%, respectively). Major cardiovascular events (MACE) occurred in 29.3% of RCM, 10.5% of DCM, 5.3% of HCM, and 3.9% of ARVC (P < 0.001). MACE were more frequent in index patients compared to relatives (10.8% vs. 4.4%, P < 0.001), more frequent in East Europe centres (13.1%) and least common in South Europe (5.3%) (P < 0.001). Subtype of cardiomyopathy, geographical region, and proband were predictors of MACE on multivariable analysis.

CONCLUSIONS

Despite symptomatic improvement, patients with cardiomyopathies remain prone to major clinical events in the short term. Outcomes were different not only according to cardiomyopathy subtypes but also in relatives vs. index patients, and according to European regions.

Left intraventricular pressure gradient in hypertrophic cardiomyopathy patients receiving implantable cardioverter-defibrillators for primary prevention

Background

Conventional risk factors for sudden cardiac death (SCD) justify primary prevention through implantable cardioverter-defibrillator (ICD) implantation in hypertrophic cardiomyopathy (HCM) patients. However, the positive predictive values for these conventional SCD risk factors are low. Left ventricular outflow tract obstruction (LVOTO) and midventricular obstruction (MVO) are potential risk modifiers for SCD. The aims of this study were to evaluate whether an elevated intraventricular pressure gradient (IVPG), including LVOTO or MVO, is a potential risk modifier for SCD and ventricular arrhythmias requiring ICD interventions in addition to the conventional risk factors among HCM patients receiving ICDs for primary prevention.

Methods

We retrospectively studied 60 HCM patients who received ICDs for primary prevention. An elevated IVPG was defined as a peak instantaneous gradient ≥ 30 mmHg at rest, as detected by continuous-wave Doppler echocardiography. The main outcome was a composite of SCD and appropriate ICD interventions, which were defined as an antitachycardia pacing or shock therapy for ventricular tachycardia or fibrillation. The Cox proportional hazards model was used to assess the relationships between risk factors and the occurrence of SCD and appropriate ICD interventions.

Results

Thirty patients met the criteria of elevated IVPG (50%). During the median follow-up period of 66 months, 2 patients experienced SCD, and 10 patients received appropriate ICD interventions. Kaplan–Meier curves showed that the incidence of the main outcome was higher in patients with an IVPG ≥ 30 mmHg than in those without an IVPG ≥ 30 mmHg (log-rank P = 0.03). There were no differences in the main outcome between patients with LVOTO and patients with MVO. The combination of nonsustained ventricular tachycardia (NSVT) and IVPG ≥ 30 mmHg was found to significantly increase the risk of the main outcome (HR 6.31, 95% CI 1.36–29.25, P = 0.02). Five patients experienced ICD implant-related complications.

Conclusions

Our findings showed that a baseline IVPG ≥ 30 mmHg was associated with an increased risk of experiencing SCD or appropriate ICD interventions among HCM patients who received ICDs for primary prevention. Combined with NSVT, which is a conventional risk factor, a baseline IVPG ≥ 30 mmHg may be a potential modifier of SCD risk in HCM patients.

Towards an Enhanced Tool for Quantifying the Degree of LV Hyper-Trabeculation

Left ventricular non-compaction (LVNC) is defined by an increase of trabeculations in left ventricular (LV) endomyocardium. Although LVNC can be in isolation, an increase in hypertrabeculation often accompanies genetic cardiomyopathies. Current methods for quantification of LV trabeculae have limitations. Several improvements are proposed and implemented to enhance a software tool to quantify the trabeculae degree in the LV myocardium in an accurate and automatic way for a population of patients with genetic cardiomyopathies (QLVTHCI). The software tool is developed and evaluated for a population of 59 patients (470 end-diastole cardiac magnetic resonance images). This tool produces volumes of the compact sector and the trabecular area, the proportion between these volumes, and the left ventricular and trabeculated masses. Substantial enhancements are obtained over the manual process performed by cardiologists, so saving important diagnosis time. The parallelization of the detection of the external layer is proposed to ensure real-time processing of a patient, obtaining speed-ups from 7.5 to 1500 with regard to QLVTHCI and the manual process used traditionally by cardiologists. Comparing the method proposed with the fractal proposal to differentiate LVNC and non-LVNC patients among 27 subjects with previously diagnosed cardiomyopathies, QLVTHCI presents a full diagnostic accuracy, while the fractal criteria achieve 78%. Moreover, QLTVHCI can be installed and integrated in hospitals on request, whereas the high cost of the license of the fractal method per year of this tool has prevented reproducibility by other medical centers.

Long-Term Survival of Patients With Left Ventricular Noncompaction

Background

The prognosis of left ventricular noncompaction (LVNC) remains elusive despite its recognition as a clinical entity for >30 years. We sought to identify clinical and imaging characteristics and risk factors for mortality in patients with LVNC.

Methods and Results

339 adults with LVNC seen between 2000 and 2016 were identified. LVNC was defined as end‐systolic noncompacted to compacted myocardial ratio >2 (Jenni criteria) and end‐diastolic trough of trabeculation‐to‐epicardium (X):peak of trabeculation‐to‐epicardium (Y) ratio <0.5 (Chin criteria) by echocardiography; and end‐diastolic noncompacted:compacted ratio >2.3 (Petersen criteria) by magnetic resonance imaging. Median age was 47.4 years, and 46% of patients were female. Left ventricular ejection fraction <50% was present in 57% of patients and isolated apical noncompaction in 48%. During a median follow‐up of 6.3 years, 59 patients died. On multivariable Cox regression analysis, age (hazard ratio [HR] 1.04; 95% CI, 1.02–1.06), left ventricular ejection fraction <50% (HR, 2.37; 95% CI, 1.17–4.80), and noncompaction extending from the apex to the mid or basal segments (HR, 2.11; 95% CI, 1.21–3.68) were associated with all‐cause mortality. Compared with the expected survival for age‐ and sex‐matched US population, patients with LVNC had reduced overall survival (P<0.001). However, patients with LVNC with preserved left ventricular ejection fraction and patients with isolated apical noncompaction had similar survival to the general population.

Conclusions

Overall survival is reduced in patients with LVNC compared with the expected survival of age‐ and sex‐matched US population. However, survival rate in those with preserved left ventricular ejection fraction and isolated apical noncompaction was comparable with that of the general population.

Mortality Among Referral Patients With Hypertrophic Cardiomyopathy vs the General European Population

Importance

It is unclear whether hypertrophic cardiomyopathy (HCM) conveys excess mortality when compared with the general population.

Objective

To compare the survival of patients with HCM with that of the general European population.

Design, Setting, and Participants

Retrospective cohort study of 4893 consecutive adult patients with HCM presenting at 7 European referral centers between 1980 and 2013. The data were analyzed between April 2018 and August 2019.

Main Outcomes and Measures

Survival was compared using standardized mortality ratios (SMRs) calculated with data from Eurostat, stratified by study period, country, sex, and age, and using a composite end point in the HCM cohort of all-cause mortality, aborted sudden cardiac death, and heart transplant.

Results

Of 4893 patients with HCM, 3126 (63.9%) were male, and the mean (SD) age at presentation was 49.2 (16.4) years. During a median follow-up of 6.2 years (interquartile range, 3.1-9.8 years), 721 patients (14.7%) reached the composite end point. Compared with the general population, patients with HCM had excess mortality throughout the age spectrum (SMR, 2.0, 95% CI, 1.48-2.63). Excess mortality was highest among patients presenting prior to the year 2000 but persisted in the cohort presenting between 2006 and 2013 (SMR, 1.84; 95% CI, 1.55-2.18). Women had higher excess mortality than men (SMR, 2.66; 95% CI, 2.38-2.97; vs SMR, 1.68; 95% CI, 1.52-1.85; P < .001).

Conclusions and Relevance

Among patients referred to European specialty centers, HCM was associated with significant excess mortality through the life course. Although there have been improvements in survival with time, potentially reflecting improved treatments for HCM, these findings highlight the need for more research into the causes of excess mortality among patients with HCM and for better risk stratification.

Assessing the relationship between systemic immune-inflammation index and mortality in patients with hypertrophic cardiomyopathy

BACKGROUND

This study investigates the predictive value of the systemic immune-inflammation index (SII), which was calculated as platelet × neutrophil/lymphocyte ratio, for all-cause mortality in patients with hypertrophic cardiomyopathy (HCM).

METHODS

A total of 360 HCM patients were enrolled. They were divided into three groups based on the tertiles of baseline SII. The association between SII and all-cause mortality was analyzed.

RESULTS

There were 53 HCM patients who died during a mean follow-up time of 4.8 years (min: 6 days and max: 10.8 years), and the mortality rate was 3.0 per 100 person years. The cumulative mortality rate was significantly different among the three tertiles of SII (P = 0.004), and the mortality rate in tertile 3 was much higher than that in the first two tertiles. In reference to tertile 1, the fully adjusted hazard ratios of all-cause mortality were 1.02 for the tertile 2 (95% confidence interval [CI]: 0.45-2.31, P = 0.966) and 2.31 for tertile 3 (95% CI: 1.10-4.87, P = 0.027). No significant interactions between SII and other variables were observed during subgroup analysis. The discriminative power was better for mid-term outcome than that for short-term or long-term outcomes. Sensitivity analyses including patients with normal platelet and white blood cell count have revealed similar results.

CONCLUSION

SII was a significant risk factor for all-cause mortality in HCM patients. However, the discriminative power was poor to moderate. It could be used in combination with other risk factors in mortality risk stratification in HCM.

QRS-T angle in patients with Hypertrophic Cardiomyopathy - A comparison with Cardiac Magnetic Resonance Imaging

Objective: We sought to investigate the possible association of a wide QRS-T angle on the surface EKG and myocardial fibrosis on contrast-enhanced cardiovascular magnetic (CMR) imaging in patients with hypertrophic cardiomyopathy (HCM). Background: Risk stratification in HCM patients is challenging. Late gadolinium enhancement (LGE) visualizes myocardial fibrosis with unique spatial resolution and is a strong and independent prognosticator in these patients. The QRS-T angle from the surface EKG is a promising prognostic marker in various cardiac pathologies. Methods: 70 patients with HCM obtained a standardized digital 12-lead EKG for the calculation of the QRS-T angle and underwent comprehensive CMR imaging for visualization of fibrosis by LGE. Patients were divided into groups according to the absence or presence of fibrosis on CMR. Results: 43 of 70 patients with HCM showed LGE on CMR following contrast administration. HCM patients with LGE (fibrosis) had wider QRS-T angles as compared to the patient group without LGE (100±54 vs. 46±31; <0.001). A QRS-T angle of 90 degrees or more was a strong predictor (OR 32.84, CI 4.08-264.47; p <0.001) of HCM with LGE. Conclusion: There is a strong association of a wide QRS-T angle and myocardial fibrosis in patients with HCM.

Risk stratification using late gadolinium enhancement on cardiac magnetic resonance imaging in patients with hypertrophic cardiomyopathy: A systematic review and meta-analysis

Background The role of late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (c-MRI) for predicting outcomes of patients with hypertrophic cardiomyopathy (HCM) has been debated. Methods We searched PubMed and Embase and various published bibliographies for prospective studies published in English between January 1990 and February 2019. Two investigators screened 2646 abstracts and full-text articles for inclusion and relevant outcomes. We then performed a systematic review and meta-analysis to calculate pooled odds ratios for LGE on c-MRI and a pooled sensitivity and specificity analysis. Results Our systematic review included 8 prospective studies and 3808 patients. LGE positivity was associated with higher odds of the endpoint of sudden cardiac death (SCD;OR 1.69, 95%CI 1.03-2.78), aborted SCD or appropriate implantable cardioverter- defibrillator (ICD) discharge (OR 3.27 [1.75-6.10]), SCD or aborted SCD or appropriate ICD discharge (OR 2.32 [1.56-3.43]), and all-cause mortality (OR 2.10 [CI 1.00-4.41]). The pooled sensitivity and specificity of positive LGE on c-MRI for SCD were 65% and 42%, respectively; for aborted SCD or appropriate ICD discharge, 79% and 39%; for SCD or aborted SCD or appropriate ICD discharge, 74% and 39%; and for all-cause mortality, 78% and 39%. Conclusion In patients with HCM, LGE on c-MRI is a strong predictor of arrhythmic outcomes including SCD, aborted SCD, and appropriate ICD therapy. These data support the routine use of LGE on c-MRI as a marker of SCD risk in this population.

Hypertrophic Cardiomyopathy in Pregnancy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiac condition and highly heterogeneous. Echocardiography and genetic and clinical screening have led to detection in women of childbearing age. Maternal and fetal outcomes among women with HCM are favorable. Genetic counseling is recommended. Prepregnancy clinical evaluation and risk assessment are paramount in ensuring optimal outcomes. Most women carry moderate risk of morbidity, have clinical evaluations and echocardiography each trimester, and deliver vaginally. Those who are symptomatic or have significant left ventricular outflow obstruction or recurrent arrhythmias prior to pregnancy are at higher risk and should be monitored at least monthly.