Effect of Gender and Genetic Mutations on Outcomes in Patients With Hypertrophic Cardiomyopathy

Survival analysis and gender differences in hypertrophic cardiomyopathy proband patients referred for genetic testing

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is believed to have low overall mortality rate, that could be influenced by gender, particularly among probands. We aimed to evaluate the survival rates and possible gender differences in a homogeneous cohort of HCM proband patients, referred for genetic testing, from the same geographical area, without differences in medical care access nor clinical referral pathways.

METHODS

we compared the mortality rates of a cohort of consecutive HCM probands referred for genetic testing (2000-2022), from a Spanish region (xxx1) with a centralized genetic testing pathway, with its control reference population by Ederer II method. Gender differences were analyzed.

RESULTS

Among the 649 HCM probands included in this study, there were significantly more men than women (61.3% vs 38.7, p < 0.05), with an earlier diagnosis (53.5 vs 61.1 years old, p < 0.05). Clinical evolution or arrhythmogenic HCM profile did no show no significant gender differences. Mean follow up was 9,8 years ±6,6 SD (9,9 ± 7 vs 9,6 ± 6,1, p = 0.59). No statistically significant differences in observed mortality, expected survival and excess mortality were found in the general HCM proband cohort. However, we found a significant excess mortality in female probands with HCM. No additional differences in analysis by genetic status were identified.

CONCLUSION

Expected survival in our HCM probands did not differ from its reference population. However, despite no gender differences in phenotype severity were identified, proband HCM women did present a diagnosis delay and worse mortality outcomes.

Meta-Analysis of Penetrance and Systematic Review on Transition to Disease in Genetic Hypertrophic Cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is characterized by unexplained left ventricular hypertrophy and is classically caused by pathogenic or likely pathogenic variants (P/LP) in genes encoding sarcomere proteins. Not all subclinical variant carriers will manifest clinically overt disease because penetrance (proportion of sarcomere or sarcomere-related P/LP variant carriers who develop disease) is variable, age dependent, and not reliably predicted.

METHODS

A systematic search of the literature was performed. We used random-effects generalized linear mixed model meta-analyses to contrast the cross-sectional prevalence and penetrance of sarcomere or sarcomere-related genes in 2 different contexts: clinically-based studies on patients and families with HCM versus population or community-based studies. Longitudinal family/clinical studies were additionally analyzed to investigate the rate of phenotypic conversion from subclinical to overt HCM during follow-up.

RESULTS

In total, 455 full-text manuscripts and articles were assessed. In family/clinical studies, the prevalence of sarcomere variants in patients diagnosed with HCM was 34%. The penetrance across all genes in nonproband relatives carrying P/LP variants identified during cascade screening was 57% (95% CI, 52%-63%), and the mean age at HCM diagnosis was 38 years (95% CI, 36%-40%). Penetrance varied from ≈32% for MYL3 (myosin light chain 3) to ≈55% for MYBPC3 (myosin-binding protein C3), ≈60% for TNNT2 (troponin T2) and TNNI3 (troponin I3), and ≈65% for MYH7 (myosin heavy chain 7). Population-based genetic studies demonstrate that P/LP sarcomere variants are present in the background population but at a low prevalence of <1%. The penetrance of HCM in incidentally identified P/LP variant carriers was also substantially lower at ≈11%, ranging from 0% in Atherosclerosis Risk in Communities to 18% in UK Biobank. In longitudinal family studies, the pooled phenotypic conversion across all genes was 15% over an average of ≈8 years of follow-up, starting from a mean of ≈16 years of age. However, short-term gene-specific phenotypic conversion varied between ≈12% for MYBPC3 and ≈23% for MYH7.

CONCLUSIONS

The penetrance of P/LP variants is highly variable and influenced by currently undefined and context-dependent genetic and environmental factors. Additional longitudinal studies are needed to improve our understanding of true lifetime penetrance in families and in the community and to identify drivers of the transition from subclinical to overt HCM.

A systematic review and meta-analysis of sex differences in clinical outcomes of hypertrophic cardiomyopathy

Background

Hypertrophic cardiomyopathy (HCM) is recognized as the most prevalent form of genetic cardiomyopathy, and recent investigations have shed light on the existence of sex disparities in terms of clinical presentation, disease progression, and outcomes.

Objectives

This study aimed to systematically review the literature and perform a meta-analysis to comprehensively compare the clinical outcomes between female and male patients with HCM.

Methods

A thorough search was conducted in databases including PubMed, Embase, Cochrane Library, and Web of Science, encompassing literature from inception until June 2023. The primary endpoints examined were: (1) all-cause mortality; (2) an arrhythmic endpoint comprising sudden cardiac death (SCD), sustained ventricular tachycardia, ventricular fibrillation, or aborted SCD; and (3) a composite endpoint incorporating either (1) or (2), in addition to hospitalization for heart failure or cardiac transplantation. Pooled estimates were derived using a random-effects meta-analysis model.

Results

The analysis encompassed a total of 29 observational studies, involving 44,677 patients diagnosed with HCM, of which 16,807 were female. Baseline characteristics revealed that the female group exhibited an advanced age [55.66 ± 0.04 years vs. 50.38 ± 0.03 years, pooled mean difference (MD) = 0.31, 95% CI: 0.22-0.40, p = 0.000, I2 = 88.89%], a higher proportion of New York Heart Association class III/IV patients [pooled odds ratio (OR) = 1.94, 95% CI: 1.55-2.43, p = 0.000, I2 = 85.92%], and a greater prevalence of left ventricular outflow tract gradient greater than or equal to 30 mmHg (pooled OR = 1.48, 95% CI: 1.27-1.73, p = 0.000, I2 = 68.88%) compared to the male group. The female group were more likely to have a positive genetic test (pooled OR = 1.27, 95% CI: 1.08-1.48, p = 0.000, I2 = 42.74%) and to carry the myosin heavy chain beta 7 mutation (pooled OR = 1.26, 95% CI: 1.04-1.54, p = 0.020, I2 = 0.00%) compared to the male group. Female sex exhibited a significant association with increased risks of all-cause mortality (pooled OR = 1.62, 95% CI: 1.38-1.89, p = 0.000, I2 = 72.78%) and the composite endpoint (pooled OR = 1.47, 95% CI: 1.20-1.79, p = 0.000, I2 = 84.96%), while no substantial difference was observed in the arrhythmic endpoint (pooled OR = 1.08, 95% CI: 0.87-1.34, p = 0.490, I2 = 55.48%).

Conclusions

The present findings suggest that female patients with HCM tend to experience poorer clinical outcomes. It is imperative to critically reevaluate disease definitions and enhance awareness to mitigate delays in the diagnosis and treatment of HCM in women, thereby fostering equitable healthcare practices.

Systematic Review Registration

https://www.crd.york.ac.uk/, PROSPERO (CRD42023431881).

Age and Sex Differences in the Genetics of Cardiomyopathy

Cardiomyopathy has variable penetrance. We analyzed age and sex-related genetic differences in 1,397 cardiomyopathy patients (Ontario, UK) with whole genome sequencing. Pediatric cases (n = 471) harbored more deleterious protein-coding variants in Tier 1 cardiomyopathy genes compared to adults (n = 926) (34.6% vs 25.9% respectively, p = 0.0015), with variant enrichment in constrained coding regions. Pediatric patients had a higher burden of sarcomere and lower burden of channelopathy gene variants compared to adults. Specifically, pediatric patients had more MYH7 and MYL3 variants in hypertrophic cardiomyopathy, and fewer TTN truncating variants in dilated cardiomyopathy. MYH7 variants clustered in the myosin head and neck domains in children. OBSCN was a top mutated gene in adults, enriched for protein-truncating variants. In dilated cardiomyopathy, female patients had a higher burden of z-disc gene variants compared to males. Genetic differences may explain age and sex-related variability in cardiomyopathy penetrance. Genotype-guided predictions of age of onset can inform pre-test genetic counseling. Pediatric cardiomyopathy patients were more likely to be genotype-positive than adults with a higher burden of variants in MYH7, MYL3, TNNT2, VCL. Adults had a higher burden of OBSCN and TTN variants. Females with dilated cardiomyopathy (DCM) had a higher burden of z-disc gene variants compared to males.

Mitochondrial dysfunction in human hypertrophic cardiomyopathy is linked to cardiomyocyte architecture disruption and corrected by improving NADH-driven mitochondrial respiration

AIMS

Genetic hypertrophic cardiomyopathy (HCM) is caused by mutations in sarcomere protein-encoding genes (i.e. genotype-positive HCM). In an increasing number of patients, HCM occurs in the absence of a mutation (i.e. genotype-negative HCM). Mitochondrial dysfunction is thought to be a key driver of pathological remodelling in HCM. Reports of mitochondrial respiratory function and specific disease-modifying treatment options in patients with HCM are scarce.

METHODS AND RESULTS

Respirometry was performed on septal myectomy tissue from patients with HCM (n = 59) to evaluate oxidative phosphorylation and fatty acid oxidation. Mitochondrial dysfunction was most notably reflected by impaired NADH-linked respiration. In genotype-negative patients, but not genotype-positive patients, NADH-linked respiration was markedly depressed in patients with an indexed septal thickness ≥10 compared with <10. Mitochondrial dysfunction was not explained by reduced abundance or fragmentation of mitochondria, as evaluated by transmission electron microscopy. Rather, improper organization of mitochondria relative to myofibrils (expressed as a percentage of disorganized mitochondria) was strongly associated with mitochondrial dysfunction. Pre-incubation with the cardiolipin-stabilizing drug elamipretide and raising mitochondrial NAD+ levels both boosted NADH-linked respiration.

CONCLUSION

Mitochondrial dysfunction is explained by cardiomyocyte architecture disruption and is linked to septal hypertrophy in genotype-negative HCM. Despite severe myocardial remodelling mitochondria were responsive to treatments aimed at restoring respiratory function, eliciting the mitochondria as a drug target to prevent and ameliorate cardiac disease in HCM. Mitochondria-targeting therapy may particularly benefit genotype-negative patients with HCM, given the tight link between mitochondrial impairment and septal thickening in this subpopulation.

Ischaemic events in hypertrophic cardiomyopathy patients with and without atrial fibrillation: a systematic review and meta-analysis

Hypertrophic cardiomyopathy predisposes to acute cerebrovascular events including ischaemic stroke, transient ischaemic attack and systemic thromboembolism. Atrial fibrillation confers even higher risk. We aim to report the incidence of these complications and to investigate the impact of atrial fibrillation on the ischaemic risk in patients with hypertrophic cardiomyopathy. A literature search was performed on PubMed, Scopus, Embase/Ovid and Cochrane library from inception to 20th March 2021. We compared the incidence of ischaemic strokes, transient ischaemic attack, non-specified thromboembolism events and systemic thromboembolism in hypertrophic cardiomyopathy patients with or without atrial fibrillation. Non-specified thromboembolism events in our paper referred to thromboembolic events whereby types were not specified in the studies. Meta-analysis was performed using StataSE 16 software, and heterogeneity was assessed using I² test. A total of 713 studies were identified. Thirty-five articles with 42,570 patients were included. The pooled incidence of stroke/ transient ischaemic attack was 7.45% (95% confidence interval [CI] 5.80-9.52, p < 0.001) across 24 studies with a total of 37,643 hypertrophic cardiomyopathy patients. Atrial fibrillation significantly increased the risk of total stroke/ transient ischaemic attack (Risk Ratio 3.26, 95% CI 1.75-6.08, p < 0.001, I² = 76.0). The incidence of stroke/ transient ischaemic attack was 9.30% (95% CI 6.64-12.87, p = 0.316) in the apical hypertrophic cardiomyopathy subgroup. Concomitant atrial fibrillation in hypertrophic cardiomyopathy increases the risk of thromboembolic events including ischaemic stroke and transient ischaemic attack. The apical subgroup shows a similar risk of acute cerebrovascular events as the overall hypertrophic cardiomyopathy population.

Prognostic significance of left atrial strain in sarcomere gene variant carriers without hypertrophic cardiomyopathy

Background

Genetic testing of relatives of hypertrophic cardiomyopathy (HCM) patients has led to a large group of genotype‐positive, phenotype‐negative (G+/Ph−) subjects. Prediction of progression to overt HCM in these subjects is challenging. While left atrial (LA) strain is reduced in HCM patients it is currently unknown whether this parameter can be used to predict HCM phenotype progression.

Methods

This study includes 91 G+/Ph− subjects and 115 controls. Standard echocardiographic parameters as well as left ventricular global longitudinal strain (LV GLS) and LA reservoir strain (LASr) were assessed for each patient. Logistic and Cox proportional hazard regression analyses were used to investigate predictors of G+/Ph− status and HCM during follow‐up.

Results

Independent predictors of G+ status included pathological Q waves (OR 1.60 [1.15–2.23], p < .01), maximal wall thickness (MWT: OR 1.10 [1.07–1.14], p < .001), mitral inflow E wave (OR 1.06 [1.02–1.10, p = .001), A wave (OR 1.06 [1.03–1.10], p < .001), LV GLS (OR .96 [.94–.98], p < .001), and LASr (OR .99 [.97–.99], p = .03). In univariable Cox regression analysis, male sex (HR 2.78 [1.06–7.29], p = .04), MWT (HR 1.72 [1.14–2.57], p = .009) and posterior wall thickness (HR 1.65 [1.17–2.30], p = .004) predicted HCM during a median follow‐up of 5.9 [3.2–8.6] years, whereas LASr did not (HR .95 [.89–1.02], p = .14). There were no significant predictors of HCM after multivariable adjustment.

Conclusion

LASr is significantly impaired in G+/Ph− subjects and is an independent predictor of G+/Ph− status, but did not predict HCM development during follow‐up.

Gender disparities in alcohol septal ablation for hypertrophic obstructive cardiomyopathy

OBJECTIVE

Alcohol septal ablation (ASA) improves symptoms in hypertrophic obstructive cardiomyopathy (HOCM). We conducted a large retrospective analysis investigating gender effects on outcome after ASA.

METHODS AND RESULTS

1367 ASAs between 2002 and 2020 were analysed. Women (47.2%) were older (66.0 years (IQR 55.0-74.0) vs 54.0 years (IQR 45.0-62.0); p<0.0001) with more severe symptoms. The interventricular septal diameter (IVSD) was higher in men (21.0 mm (IQR 19.0-24.0) vs 20.0 mm (IQR 18.0-23.0); p<0.0001) but the IVSD indexed to body surface area was higher in women (10.9 mm/m² (IQR 9.7-12.7) vs 10.2 mm/m² (IQR 9.0-11.7); p<0.0001). Women had lower exercise-induced left ventricular outflow tract gradients (LVOTG) 1-4 days after ASA (55.0 mm Hg (IQR 30.0-109.0) vs 71.0 mm Hg (IQR 37.0-115.0); p=0.0006). There was a trend for lower resting LVOTG 1-4 days after ASA (20.0 mm Hg (IQR 12.0-37.5) vs 22.0 mm Hg (IQR 13.0-40.0); p=0.0062) and lower exercise-induced LVOTG after 6 months in women (34.0 mm Hg (IQR 21.0-70.0) vs 43.5 mm Hg (IQR 25.0-74.8); p=0.0072), but this was not statistically significant after Bonferroni correction. More women developed atrioventricular (AV) block (20.3% vs 13.3%; p=0.0005) and required a pacemaker (17.4% vs 10.4%; p=0.0002) but not a cardioverter defibrillator (9.0% vs 11.6% in men; p=n .s.). However, in multivariable regression models, there was no evidence that sex independently influenced LVOTG and the occurrence of AV block.

CONCLUSION

Female patients with HOCM were older and had more advanced disease at the time of ASA. Women had superior short-term haemodynamic response to ASA but more often developed AV block after ASA. These results are important to consider for sex-specific counselling before ASA.

Contemporary family screening in hypertrophic cardiomyopathy: the role of cardiovascular magnetic resonance

Aims

Genetic testing in relatives of hypertrophic cardiomyopathy (HCM) patients leads to early identification of pathogenic DNA variant carriers (G+), before the onset of left ventricular hypertrophy. Routine phenotyping consists of electrocardiography (ECG) and transthoracic echocardiography (TTE). Cardiovascular magnetic resonance (CMR) has become valuable in the work-up of HCM. In this study, we investigated the value of CMR in phenotyping of G+ family members.

Methods and results

This study included 91 G+ subjects who underwent ECG, TTE and CMR, with a maximal wall thickness (MWT) <15 mm on TTE. The relative performance of TTE and CMR regarding wall thickness measurements and HCM diagnoses was assessed. HCM was defined as MWT of ≥13 mm. Logistic regression was performed to assess whether ECG and TTE parameters can predict CMR results. Most subjects (75%) had an MWT <13 mm on TTE, of which 23 (34%) were diagnosed with HCM based on CMR. MWT differences (range 1–10 mm) were often caused by an anterobasal hook-shaped thickening of the myocardium not visible on TTE. Two of 23 (9%) subjects with HCM on TTE were reclassified as no HCM on CMR. Normal ECG and TTE results almost excluded reclassifications by CMR. The prevalence of other HCM-related abnormalities on CMR was low.

Conclusion

CMR reclassified 27% of subjects. Subjects with normal ECG/TTE results were reclassified in a low number of cases, justifying screening with ECG and TTE in G+ relatives. In subjects with abnormal ECGs and/or poor TTE image quality, CMR is indicated.

Diagnostic validity and clinical utility of genetic testing for hypertrophic cardiomyopathy: a systematic review and meta-analysis

Objective

This study summarises the diagnostic validity and clinical utility of genetic testing for patients with hypertrophic cardiomyopathy (HCM) and their at-risk relatives.

Methods

A systematic search was performed in PubMed (MEDLINE), Embase, CINAHL and Cochrane Central Library databases from inception through 2 March 2020. Subgroup and sensitivity analyses were prespecified for individual sarcomere genes, presence/absence of pathogenic variants, paediatric and adult cohorts, family history, inclusion of probands, and variant classification method. Study quality was assessed using the Newcastle-Ottawa tool.

Results

A total of 132 articles met inclusion criteria. The detection rate based on pathogenic and likely pathogenic variants was significantly higher in paediatric cohorts compared with adults (56% vs 42%; p=0.01) and in adults with a family history compared with sporadic cases (59% vs 33%; p=0.005). When studies applied current, improved, variant interpretation standards, the adult detection rate significantly decreased from 42% to 33% (p=0.0001) because less variants met criteria to be considered pathogenic. The mean difference in age-of-onset in adults was significantly earlier for genotype-positive versus genotype-negative cohorts (8.3 years; p<0.0001), MYH7 versus MYBPC3 cohorts (8.2 years; p<0.0001) and individuals with multiple versus single variants (7.0 years; p<0.0002). Overall, disease penetrance in adult cohorts was 62%, but differed significantly depending on if probands were included or excluded (73% vs 55%; p=0.003).

Conclusions

This systematic review and meta-analysis is the first, to our knowledge, to collectively quantify historical understandings of detection rate, genotype-phenotype associations and disease penetrance for HCM, while providing the answers to important routine clinical questions and highlighting key areas for future study.

Sex differences in clinical outcomes for obstructive hypertrophic cardiomyopathy in the USA: a retrospective observational study of administrative claims data

OBJECTIVES

To evaluate sex differences in demographic and clinical characteristics, treatments and outcomes for patients with diagnosed obstructive hypertrophic cardiomyopathy (oHCM) in the USA.

SETTING

Retrospective observational study of administrative claims data from MarketScan Commercial Claims and Encounters Database from IBM Watson Health.

PARTICIPANTS

Of the 28 million covered employees and family members in MarketScan, 9306 patients with oHCM were included in this analysis.

MAIN OUTCOME MEASURES

oHCM-related outcomes included heart failure, atrial fibrillation, ventricular tachycardia/ fibrillation, sudden cardiac death, septal myectomy, alcohol septal ablation (ASA) and heart transplant.

RESULTS

Among 9306 patients with oHCM, the majority were male (60.5%, p<0.001) and women were of comparable age to men (50±15 vs 49±15 years, p<0.001). Women were less likely to be prescribed beta blockers (42.7% vs 45.2%, p=0.017) and undergo an implantable cardioverter-defibrillator (1.7% vs 2.6%, p=0.005). Septal reduction therapy was performed slightly more frequently in women (ASA: 0.08% vs 0.05%, p=0.600; SM: 0.35% vs 0.18%, p=0.096), although not statistically significant. Women were less likely to have atrial fibrillation (6.7% vs 9.9%, p<0.001).

CONCLUSION

Women were less likely to be prescribed beta blockers, ACE inhibitors, anticoagulants, undergo implantable cardioverter-defibrillator and have ventricular tachycardia/fibrillation. Men were more likely to have atrial fibrillation. Future research using large, clinical real-world data are warranted to understand the root cause of these potential treatment disparities in women with oHCM.

Gender-Related Differences in Hypertrophic Cardiomyopathy: A Systematic Review and Meta-Analysis

Background

Gender-related differences in phenotypic expression and outcomes have been established in many cardiac conditions; however, the impact of gender in hypertrophic cardiomyopathy (HCM) remains unclear. We conducted a systematic review and meta-analysis to assess the differences in clinical outcomes between female and male HCM patients.

Methods

We searched MEDLINE and EMBASE from inception to October 2020. Included were cohort studies that compared outcomes of interest including all-cause mortality, HCM-related mortality, and worsening heart failure (HF) or HF hospitalization between male and female. Data from each study were combined using the random effects model to calculate pooled odds ratio (OR) with 95% confidence interval (CI).

Results

Eleven retrospective cohort studies with a total of 9,427 patients (3,719 females) were included. Female gender was significantly associated with an increased risk of all-cause mortality (pooled OR = 1.63, 95% CI: 1.26-2.10, p ≤ 0.001), HCM-related mortality (pooled OR = 1.47, 95% CI: 1.08-2.01, p = 0.015), and worsening HF or HF hospitalization (pooled OR = 2.05, 95% CI: 1.76-2.39, p ≤ 0.001).

Conclusions

Female gender was associated with a worse prognosis in HCM. These findings suggest the need for improved care in women including early identification of disease and more possible aggressive management. Moreover, gender-based strategy may benefit in HCM patients.

Sex Differences in Time-Dependent Changes in B-Type Natriuretic Peptide in Hypertrophic Cardiomyopathy

Background: Female sex is reported to be associated with poor prognosis in hypertrophic cardiomyopathy (HCM). The plasma B-type natriuretic peptide (BNP) concentration is a prognostic predictor in HCM. However, the effect of sex on BNP concentrations remains unclear among HCM patients.

Methods and Results: Patient records in the Clinical Personal Records of HCM national database of the Japanese Ministry of Health, Labour and Welfare from 2009 to 2014 were analyzed. Of 3,570 HCM patients, 611 in whom BNP concentrations were assessed at both baseline and the 2-year follow-up were included in this analysis. The mean age was 60.4 years and 254 (41.6%) patients were female. Median (interquartile range) BNP concentrations were higher in females than males at both baseline (320.3 [159.0–583.1] vs. 182.8 [86.1–363.9] pg/mL; P<0.001) and the 2-year follow-up (299.2 [147.0–535.3] vs. 161.0 [76.2–310.0] pg/mL; P<0.001). Female sex was associated with higher natural log-transformed BNP at the 2-year follow-up regardless of clinical characteristics, including echocardiographic findings and BNP concentrations at baseline (coefficient 0.31; 95% confidence interval 0.13–0.48; P<0.001). Cubic spline analysis showed that, among patients with high BNP concentrations at baseline, females had higher BNP concentrations at the 2-year follow-up than males.

Conclusions: In HCM, female sex was associated with higher BNP concentrations than male sex, independent of clinical characteristics, including BNP concentrations at baseline.

Novel Morphological Features on CMR for the Prediction of Pathogenic Sarcomere Gene Variants in Subjects Without Hypertrophic Cardiomyopathy

Background: Carriers of pathogenic DNA variants (G+) causing hypertrophic cardiomyopathy (HCM) can be identified by genetic testing. Several abnormalities have been brought forth as pre-clinical expressions of HCM, some of which can be identified by cardiovascular magnetic resonance (CMR). In this study, we assessed morphological differences between G+/left ventricular hypertrophy-negative (LVH-) subjects and healthy controls and examined whether CMR-derived variables are useful for the prediction of sarcomere gene variants.

Methods: We studied 57 G+ subjects with a maximal wall thickness (MWT) < 13 mm, and compared them to 40 healthy controls matched for age and sex on a group level. Subjects underwent CMR including morphological, volumetric and function assessment. Logistic regression analysis was performed for the determination of predictive CMR characteristics, by which a scoring system for G+ status was constructed.

Results: G+/LVH- subjects were subject to alterations in the myocardial architecture, resulting in a thinner posterior wall thickness (PWT), higher interventricular septal wall/PWT ratio and MWT/PWT ratio. Prominent hook-shaped configurations of the anterobasal segment were only observed in this group. A model consisting of the anterobasal hook, multiple myocardial crypts, right ventricular/left ventricular ratio, MWT/PWT ratio, and MWT/left ventricular mass ratio predicted G+ status with an area under the curve of 0.92 [0.87–0.97]. A score of ≥3 was present only in G+ subjects, identifying 56% of the G+/LVH- population.

Conclusion: A score system incorporating CMR-derived variables correctly identified 56% of G+ subjects. Our results provide further insights into the wide phenotypic spectrum of G+/LVH- subjects and demonstrate the utility of several novel morphological features. If genetic testing for some reason cannot be performed, CMR and our purposed score system can be used to detect possible G+ carriers and to aid planning of the control intervals.

Sex-Related Differences in Protein Expression in Sarcomere Mutation-Positive Hypertrophic Cardiomyopathy

Background: Sex-differences in clinical presentation contribute to the phenotypic heterogeneity of hypertrophic cardiomyopathy (HCM) patients. While disease prevalence is higher in men, women present with more severe diastolic dysfunction and worse survival. Until today, little is known about the cellular differences underlying sex-differences in clinical presentation.

Methods: To define sex-differences at the protein level, we performed a proteomic analysis in cardiac tissue obtained during myectomy surgery to relieve left ventricular outflow tract obstruction of age-matched female and male HCM patients harboring a sarcomere mutation (n = 13 in both groups). Furthermore, these samples were compared to 8 non-failing controls. Women presented with more severe diastolic dysfunction.

Results: Out of 2099 quantified proteins, direct comparison of male, and female HCM samples revealed only 46 significantly differentially expressed proteins. Increased levels of tubulin and heat shock proteins were observed in female compared to male HCM patients. Western blot analyses confirmed higher levels of tubulin in female HCM samples. In addition, proteins involved in carbohydrate metabolism were significantly lower in female compared to male samples. Furthermore, we found lower levels of translational proteins specifically in male HCM samples. The disease-specificity of these changes were confirmed by a second analysis in which we compared female and male samples separately to non-failing control samples. Transcription factor analysis showed that sex hormone-dependent transcription factors may contribute to differential protein expression, but do not explain the majority of protein changes observed between male and female HCM samples.

Conclusion: In conclusion, based on our proteomics analyses we propose that increased levels of tubulin partly underlie more severe diastolic dysfunction in women compared to men. Since heat shock proteins have cardioprotective effects, elevated levels of heat shock proteins in females may contribute to later disease onset in woman, while reduced protein turnover in men may lead to the accumulation of damaged proteins which in turn affects proper cellular function.

Shared genetic pathways contribute to risk of hypertrophic and dilated cardiomyopathies with opposite directions of effect

The heart muscle diseases hypertrophic (HCM) and dilated (DCM) cardiomyopathies are leading causes of sudden death and heart failure in young, otherwise healthy, individuals. We conducted genome-wide association studies and multi-trait analyses in HCM (1,733 cases), DCM (5,521 cases) and nine left ventricular (LV) traits (19,260 UK Biobank participants with structurally normal hearts). We identified 16 loci associated with HCM, 13 with DCM and 23 with LV traits. We show strong genetic correlations between LV traits and cardiomyopathies, with opposing effects in HCM and DCM. Two-sample Mendelian randomization supports a causal association linking increased LV contractility with HCM risk. A polygenic risk score explains a significant portion of phenotypic variability in carriers of HCM-causing rare variants. Our findings thus provide evidence that polygenic risk score may account for variability in Mendelian diseases. More broadly, we provide insights into how genetic pathways may lead to distinct disorders through opposing genetic effects.

Targeting the population for gene therapy with MYBPC3

Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited myocardial disease characterized by unexplained left ventricular hypertrophy, diastolic dysfunction and myocardial disarray. Clinical heterogeneity is wide, ranging from asymptomatic individuals to heart failure, arrhythmias and sudden death. HCM is often caused by mutations in genes encoding components of the sarcomere. Among them, MYBPC3, encoding cardiac myosin-myosin binding protein C is the most frequently mutated gene. Three quarter of pathogenic or likely pathogenic mutations in MYBPC3 are truncating and the resulting protein was not detected in HCM myectomy samples. The overall prognosis of the patients is excellent if managed with contemporary therapy, but still remains a significant disease-related health burden, and carriers with double heterozygous, compound heterozygous and homozygous mutations often display a more severe clinical phenotype than single heterozygotes. We propose these individuals as a good target population for MYBPC3 gene therapy.

Impact of sex on timing and clinical outcome of septal myectomy for obstructive hypertrophic cardiomyopathy

BACKGROUND

Sex disparities are common in hypertrophic cardiomyopathy (HCM). Previous research has shown that at time of myectomy, women are older, have greater impairment of diastolic function and more advanced cardiac remodeling. The clinical impact of these differences is unknown.

METHOD

This study included 162 HCM patients (61% men) who underwent septal myectomy. Time to treatment was calculated in relation to symptom onset and diagnosis. Pre- and post-operative echocardiographic data were collected. Sex differences were assessed at baseline and in time-to-event survival analyses for the composite endpoint of all-cause mortality, cardiac transplantation, re-intervention and aborted sudden cardiac death.

RESULTS

Women were generally older at time of myectomy (57 vs. 49 years, p < 0.01), with similar time to treatment as measured from symptom onset (2.3 [1.3-6.0] vs. 2.8 [1.1-5.3] years, p > 0.05), but a shorter time since diagnosis compared to men (2.6 [1.2-7.0] vs. 4.3 [2.4-8.3] years, p = 0.02). Mean wall thickness and left atrial diameter were the same for men and women, but were higher in women when correcting for body surface area (absolute: 20 vs. 19 mm, 48 vs 46 mm, p ≥ 0.05; corrected: 9.7 vs. 11.2 mm/m², 23.4 vs. 26.3 mm/m², p < 0.01). After 5.9 [3.0-9.1] years, 15% of men and 8% of women had reached the composite endpoint (p > 0.05).

CONCLUSION

In conclusion, although women present later in life and seem to have more advanced disease on echocardiography, time until myectomy was similar and clinical outcomes after myectomy are favourable for both men and women.

Left-ventricular outflow tract acceleration time is associated with symptoms in patients with obstructive hypertrophic cardiomyopathy

Aims

Not all obstructive hypertrophic cardiomyopathy (HCM) patients are symptomatic. The relation between obstructive HCM and symptoms is not well understood. The hypothesis of this study is that left-ventricular outflow tract (LVOT) acceleration time (AT) is associated with symptoms.

Methods

We included 187 patients (61% men, mean age 55 ± 14 years) with obstructive HCM, defined as a maximal wall thickness ≥ 15 mm and a resting or provoked LVOT peak gradient ≥ 30 mmHg. Peak velocity (PV), left-ventricular (LV) ejection time (ET), and AT (the time between LVOT flow onset and the moment of PV) were measured on continuous-wave (CW) Doppler tracings. Logistic and Cox proportional hazard regression analyses were used to evaluate the relation between symptoms [New York Heart Association (NYHA) class ≥ II] and echocardiographic measurements, including AT. Reproducibility was assessed using the intraclass correlation coefficient (ICC).

Results

Symptomatic patients were more often female and had higher mean AT values. Logistic regression demonstrated a significant association between AT and symptomatic status (odds ratio 1.31 per 10 ms, p < 0.01) after adjustment for sex, negative inotropes, PV, LVOT diameter, and diastolic dysfunction. AT was independently associated with symptoms and septal reduction during follow-up (hazard ratio 1.09 per 10 ms, p < 0.05). The ICC was 0.98 with a mean difference of 0.28 ± 8.4 ms.

Conclusion

In obstructive HCM patients, increased AT is significantly related to symptoms after adjustment for sex, negative inotropes, PV, LVOT diameter, and diastolic dysfunction, and is associated with the symptomatic status during follow-up. AT represents an easily measured echocardiographic variable with excellent inter-reader reproducibility.

Electronic supplementary material

The online version of this article (10.1007/s40477-020-00513-3) contains supplementary material, which is available to authorized users.

Sex-specific cardiac remodeling in early and advanced stages of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most frequent genetic cardiac disease with a prevalence of 1:500 to 1:200. While most patients show obstructive HCM and a relatively stable clinical phenotype (stage II), a small group of patients progresses to end-stage HCM (stage IV) within a relatively brief period. Previous research has shown sex-differences in stage II HCM with more diastolic dysfunction in female than in male patients. Moreover, female patients more often show progression to heart failure. Here we investigated if differences in functional and structural properties of the heart may underlie sex-differences in disease progression from stage II to stage IV HCM. Cardiac tissue from stage II and IV patients was obtained during myectomy (n = 54) and heart transplantation (n = 10), respectively. Isometric force was measured in membrane-permeabilized cardiomyocytes to define active and passive myofilament force development. Titin isoform composition was assessed using gel electrophoresis, and the amount of fibrosis and capillary density were determined with histology. In accordance with disease stage-dependent adverse cardiac remodeling end-stage patients showed a thinner interventricular septal wall and larger left ventricular and atrial diameters compared to stage II patients. Cardiomyocyte contractile properties and fibrosis were comparable between stage II and IV, while capillary density was significantly lower in stage IV compared to stage II. Women showed more adverse cellular remodeling compared to men at stage II, evident from more compliant titin, more fibrosis and lower capillary density. However, the disease stage-dependent reduction in capillary density was largest in men. In conclusion, the more severe cellular remodeling in female compared to male stage II patients suggests a more advanced disease stage at the time of myectomy in women. Changes in cardiomyocyte contractile properties do not explain the progression of stage II to stage IV, while reduced capillary density may underlie disease progression to end-stage heart failure.

Impact of Sex on Clinical Course and Survival in the Contemporary Treatment Era for Hypertrophic Cardiomyopathy

Background

The relation of sex to clinical presentation and course in hypertrophic cardiomyopathy (HCM) remains incompletely resolved. We assessed differences in clinical outcomes between men and women within our large HCM cohort.

Methods and Results

Of 2123 consecutive patients, a minority (38%) were women who were diagnosed with HCM at older ages or referred for subspecialty evaluation later than men (50±19 versus 44±16 and 55±18 versus 49±16; P<0.001). Women more commonly developed advanced New York Heart Association class III/IV symptoms (53% versus 35% in men; P<0.001), predominantly secondary to outflow obstruction. While end‐stage heart failure with systolic dysfunction (ejection fraction <50%) was similar in men (5% versus 4% in women; P=0.33), women were 3‐fold more likely to develop heart failure with preserved systolic function (7.5% versus 2.6%; P=0.002). Sudden death events terminated by defibrillator therapy were similar in women (0.9%/year) versus men (1.0%/year; hazard ratio, 0.92; 95% CI, 0.6–1.5; P=0.73). HCM mortality was uncommon, with identical rates in both sexes (0.3%/year; hazard ratio, 1.5; 95% CI, 0.7–3.4;, P=0.25). Age‐adjusted all‐cause mortality also did not differ between women and men (1.7% versus 1.3%/year; hazard ratio, 1.32; 95% CI, 0.92–1.91; P=0.13).

Conclusions

Survival was not less favorable in women with HCM. Contemporary treatments including surgical myectomy to reverse heart failure and defibrillators to prevent sudden death, were effective in both sexes contributing to low mortality. However, despite more frequent outflow obstruction, women with HCM are underrecognized and referred to centers later than men, often with more advanced heart failure. Greater awareness of HCM in women should lead to earlier diagnosis and treatment, with implications for improved quality of life.

Exploring the Continuum of Hypertrophic Cardiomyopathy-From DNA to Clinical Expression

The concepts underlying hypertrophic cardiomyopathy (HCM) pathogenesis have evolved greatly over the last 60 years since the pioneering work of the British pathologist Donald Teare, presenting the autopsy findings of “asymmetric hypertrophy of the heart in young adults”. Advances in human genome analysis and cardiac imaging techniques have enriched our understanding of the complex architecture of the malady and shaped the way we perceive the illness continuum. Presently, HCM is acknowledged as “a disease of the sarcomere”, where the relationship between genotype and phenotype is not straightforward but subject to various genetic and nongenetic influences. The focus of this review is to discuss key aspects related to molecular mechanisms and imaging aspects that have prompted genotype–phenotype correlations, which will hopefully empower patient-tailored health interventions.