Penetrance of Dilated Cardiomyopathy in Genotype-Positive Relatives

BACKGROUND

Disease penetrance in genotype-positive (G+) relatives of families with dilated cardiomyopathy (DCM) and the characteristics associated with DCM onset in these individuals are unknown.

OBJECTIVES

This study sought to determine the penetrance of new DCM diagnosis in G+ relatives and to identify factors associated with DCM development.

METHODS

The authors evaluated 779 G+ patients (age 35.8 ± 17.3 years; 459 [59%] females; 367 [47%] with variants in TTN) without DCM followed at 25 Spanish centers.

RESULTS

After a median follow-up of 37.1 months (Q1-Q3: 16.3-63.8 months), 85 individuals (10.9%) developed DCM (incidence rate of 2.9 per 100 person-years; 95% CI: 2.3-3.5 per 100 person-years). DCM penetrance and age at DCM onset was different according to underlying gene group (log-rank P = 0.015 and P <0.01, respectively). In a multivariable model excluding CMR parameters, independent predictors of DCM development were: older age (HR per 1-year increase: 1.02; 95% CI: 1.0-1.04), an abnormal electrocardiogram (HR: 2.13; 95% CI: 1.38-3.29); presence of variants in motor sarcomeric genes (HR: 1.92; 95% CI: 1.05-3.50); lower left ventricular ejection fraction (HR per 1% increase: 0.86; 95% CI: 0.82-0.90) and larger left ventricular end-diastolic diameter (HR per 1-mm increase: 1.10; 95% CI: 1.06-1.13). Multivariable analysis in individuals with cardiac magnetic resonance and late gadolinium enhancement assessment (n = 360, 45%) identified late gadolinium enhancement as an additional independent predictor of DCM development (HR: 2.52; 95% CI: 1.43-4.45).

CONCLUSIONS

Following a first negative screening, approximately 11% of G+ relatives developed DCM during a median follow-up of 3 years. Older age, an abnormal electrocardiogram, lower left ventricular ejection fraction, increased left ventricular end-diastolic diameter, motor sarcomeric genetic variants, and late gadolinium enhancement are associated with a higher risk of developing DCM.

Intermediate-effect size p.Arg637Gln in FHOD3 increases risk of HCM and is associated with an aggressive phenotype in homozygous carriers

Formin homology 2 domain-containing 3 (FHOD3) gene has emerged as one of the main non-sarcomeric genes associated with hypertrophic cardiomyopathy (HCM), but no cases of biallelic variants associated with disease have been described to date. From 2014 until 2021, FHOD3 was evaluated in our center by next-generation sequencing in 22 806 consecutive unrelated probands. The p.Arg637Gln variant in FHOD3 was enriched in our HCM cohort (284 of 9668 probands; 2.94%) compared with internal controls (64 of 11 480; 0.59%) and gnomAD controls (373 of 64 409; 0.58%), with ORs of 5.40 (95% CI: 4.11 to 7.09) and 5.19 (95% CI: 4.44 to 6.07). The variant affects a highly conserved residue localised in a supercoiled alpha helix considered a clustering site for HCM variants, and in heterozygosis can act as a predisposing factor (intermediate-effect variant) for HCM, with an estimated penetrance of around 1%. Additionally, seven homozygous carriers of p.Arg637Gln in FHOD3 were identified. All but one (unaffected) showed an early presentation and a severe HCM phenotype. All this information suggest that p.Arg637Gln variant in FHOD3 is a low-penetrant variant, with an intermediate effect, that contributes to the development of HCM in simple heterozygosis, being associated with a more severe phenotype in homozygous carriers.

Efficacy and Safety of Aficamten in Symptomatic Nonobstructive Hypertrophic Cardiomyopathy: Results From the REDWOOD-HCM Trial, Cohort 4

BACKGROUND

This open-label phase 2 trial evaluated the safety and efficacy of aficamten in patients with nonobstructive hypertrophic cardiomyopathy (nHCM).

METHODS

Patients with symptomatic nHCM (left ventricular outflow tract obstruction gradient ≤ 30 mmHg, left ventricular ejection fraction [LVEF] ≥ 60%, N-terminal pro-B-type natriuretic peptide [NT-proBNP] > 300 pg/mL) received aficamten 5-15 mg once daily (doses adjusted according to echocardiographic LVEF) for 10 weeks.

RESULTS

We enrolled 41 patients (mean ± SD age 56 ± 16 years; 59% female). At Week 10, 22 (55%) patients experienced an improvement of ≥ 1 New York Heart Association class; 11 (29%) became asymptomatic. Clinically relevant improvements in Kansas City Cardiomyopathy Questionnaire Clinical Summary Scores occurred in 22 (55%) patients. Symptom relief was paralleled by reductions in NT-proBNP levels (56%; P < 0.001) and high-sensitivity cardiac troponin I (22%; P < 0.005). Modest reductions in LVEF (mean ± SD) of -5.4% ± 10 to 64.6% ± 9.1 were observed. Three (8%) patients had asymptomatic reduction in LVEF < 50% (range: 41%-48%), all returning to normal after 2 weeks of washout. One patient with prior history of aborted sudden cardiac death experienced a fatal arrhythmia during the study.

CONCLUSIONS

Aficamten administration for symptomatic nHCM was generally safe and was associated with improvements in heart failure symptoms and cardiac biomarkers.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04219826.

Clinical and Genotype Characteristics and Symptom Migration in Patients With Mixed Phenotype Transthyretin Amyloidosis from the Transthyretin Amyloidosis Outcomes Survey

INTRODUCTION

Transthyretin amyloidosis (ATTR amyloidosis) is primarily associated with a cardiac or neurologic phenotype, but a mixed phenotype is increasingly described.

METHODS

This study describes the mixed phenotype cohort in the Transthyretin Amyloidosis Outcomes Survey (THAOS). THAOS is an ongoing, longitudinal, observational survey of patients with ATTR amyloidosis, including both hereditary (ATTRv) and wild-type disease, and asymptomatic carriers of pathogenic transthyretin variants. Baseline characteristics of patients with a mixed phenotype (at enrollment or reclassified during follow-up) are described (data cutoff: January 4, 2022).

RESULTS

Approximately one-third of symptomatic patients (n = 1185/3542; 33.5%) were classified at enrollment or follow-up as mixed phenotype (median age, 66.5 years). Of those, 344 (29.0%) were reclassified to mixed phenotype within a median 1-2 years of follow-up. Most patients with mixed phenotype had ATTRv amyloidosis (75.7%). The most frequent genotypes were V30M (38.9%) and wild type (24.3%).

CONCLUSIONS

These THAOS data represent the largest analysis of a real-world mixed phenotype ATTR amyloidosis population to date and suggest that a mixed phenotype may be more prevalent than previously thought. Patients may also migrate from a primarily neurologic or cardiologic presentation to a mixed phenotype over time. These data reinforce the need for multidisciplinary evaluation at initial assessment and follow-up of all patients with ATTR amyloidosis.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00628745.

Impact of vutrisiran on exploratory cardiac parameters in hereditary transthyretin-mediated amyloidosis with polyneuropathy

AIMS

HELIOS-A was a Phase 3, open-label study of vutrisiran, an RNA interference therapeutic, in patients with hereditary transthyretin (ATTRv) amyloidosis with polyneuropathy. This analysis evaluated vutrisiran's impact on exploratory cardiac endpoints in HELIOS-A patients.

METHODS AND RESULTS

Patients were randomized 3:1 to subcutaneous vutrisiran 25 mg every 3 months or intravenous patisiran 0.3 mg/kg every 3 weeks (reference group) for 18 months. Exploratory cardiac endpoints included change from baseline in N-terminal prohormone of brain-type natriuretic peptide (NT-proBNP) and echocardiographic parameters versus external placebo (APOLLO study). The modified intent-to-treat (mITT) population comprised randomized patients receiving any study drug (n = 122). A cardiac subpopulation with evidence of cardiac amyloid involvement (n = 40) was prespecified. 99mTc scintigraphy exploratory assessments in a planned vutrisiran-treated cohort at select sites were compared with baseline. At Month 18, vutrisiran demonstrated beneficial effects on NT-proBNP versus external placebo in the mITT and cardiac subpopulations (adjusted geometric mean fold change ratio [95% confidence interval] 0.480 [0.383-0.600], p = 9.606 × 10-10 and 0.491 [0.337-0.716], p = 0.0004, respectively). Benefits or trends towards benefit in echocardiographic parameters versus external placebo were observed for both populations. In 99mTc scintigraphy assessments, 32/47 (68.1%) and 31/48 (64.6%) patients exhibited reduced normalized left ventricular total uptake and heart-to-contralateral lung ratio, respectively. Perugini grade was reduced or unchanged versus baseline in 55/57 (96.5%) evaluable patients. No increase in cardiac adverse events was observed with vutrisiran versus external placebo.

CONCLUSIONS

Vutrisiran demonstrated evidence of potential benefit on cardiac manifestations in patients with ATTRv amyloidosis with polyneuropathy, with an acceptable safety profile.

Efficacy and Safety of Acoramidis in Transthyretin Amyloid Cardiomyopathy

BACKGROUND

Transthyretin amyloid cardiomyopathy is characterized by the deposition of misfolded monomeric transthyretin (TTR) in the heart. Acoramidis is a high-affinity TTR stabilizer that acts to inhibit dissociation of tetrameric TTR and leads to more than 90% stabilization across the dosing interval as measured ex vivo.

METHODS

In this phase 3, double-blind trial, we randomly assigned patients with transthyretin amyloid cardiomyopathy in a 2:1 ratio to receive acoramidis hydrochloride at a dose of 800 mg twice daily or matching placebo for 30 months. Efficacy was assessed in the patients who had an estimated glomerular filtration rate of at least 30 ml per minute per 1.73 m2 of body-surface area. The four-step primary hierarchical analysis included death from any cause, cardiovascular-related hospitalization, the change from baseline in the N-terminal pro-B-type natriuretic peptide (NT-proBNP) level, and the change from baseline in the 6-minute walk distance. We used the Finkelstein-Schoenfeld method to compare all potential pairs of patients within strata to generate a P value. Key secondary outcomes were death from any cause, the 6-minute walk distance, the score on the Kansas City Cardiomyopathy Questionnaire-Overall Summary, and the serum TTR level.

RESULTS

A total of 632 patients underwent randomization. The primary analysis favored acoramidis over placebo (P<0.001); the corresponding win ratio was 1.8 (95% confidence interval [CI], 1.4 to 2.2), with 63.7% of pairwise comparisons favoring acoramidis and 35.9% favoring placebo. Together, death from any cause and cardiovascular-related hospitalization contributed more than half the wins and losses to the win ratio (58% of all pairwise comparisons); NT-proBNP pairwise comparisons yielded the highest ratio of wins to losses (23.3% vs. 7.0%). The overall incidence of adverse events was similar in the acoramidis group and the placebo group (98.1% and 97.6%, respectively); serious adverse events were reported in 54.6% and 64.9% of the patients.

CONCLUSIONS

In patients with transthyretin amyloid cardiomyopathy, the receipt of acoramidis resulted in a significantly better four-step primary hierarchical outcome containing components of mortality, morbidity, and function than placebo. Adverse events were similar in the two groups. (Funded by BridgeBio Pharma; ATTRibute-CM ClinicalTrials.gov number, NCT03860935.).

Feasibility and safety of left bundle branch area pacing in cardiac amyloidosis. A single center experience

BACKGROUND

Conventional right ventricle (RV) pacemaker stimulation has been associated with worse clinical outcomes in patients with cardiac amyloidosis (CA). Left bundle branch area pacing (LABPP) has been suggested as a promising alternative. We sought to assess the safety, feasibility, and outcomes of LABPP in patients with CA.

METHODS

We retrospectively analyzed echocardiography and pacing parameters and clinical outcomes in 23 consecutive patients with CA and LBBAP implanted from June 2020 to October 2022.

RESULTS

LBBAP was successfully performed in 22 over 23 patients (19 male, 78.6 ± 11.7 years, 20 ATTR, mean LVEF 45.5 ± 16.2%). After the procedure, 9 patients showed Qr pattern and 11 a qR pattern in V1 on ECG. Average procedure time was 67 ± 28 min. After 7.7 ± 5.2 months follow-up, no procedure-related complications had occurred. Although, a significant reduction in QRS width (p = .001) was achieved, we did not observe significant changes in LVEF and Nt ProBNP at 6 months of follow-up. Pacing parameters were stable during follow-up: LBB capture threshold and R wave amplitude were 1.0 ±  0.5 V and 10.6 ± 6.0 mV versus 0.8 ±  0.1 V, p = .21 and 10.6 ± 5.1 mV (p = .985) at follow up.

CONCLUSION

LBBAP is safe and feasible pacing technique for patients with CA. LBBAP is associated with significant narrowing of QRSd without worsening in LVEF and Nt-proBNP.

Exercise Capacity in Patients With Obstructive Hypertrophic Cardiomyopathy: SEQUOIA-HCM Baseline Characteristics and Study Design

Patients with obstructive hypertrophic cardiomyopathy (oHCM) have increased risk of arrhythmia, stroke, heart failure, and sudden death. Contemporary management of oHCM has decreased annual hospitalization and mortality rates, yet patients have worsening health-related quality of life due to impaired exercise capacity and persistent residual symptoms. Here we consider the design of clinical trials evaluating potential oHCM therapies in the context of SEQUOIA-HCM (Safety, Efficacy, and Quantitative Understanding of Obstruction Impact of Aficamten in HCM). This large, phase 3 trial is now fully enrolled (N = 282). Baseline characteristics reflect an ethnically diverse population with characteristics typical of patients encountered clinically with substantial functional and symptom burden. The study will assess the effect of aficamten vs placebo, in addition to standard-of-care medications, on functional capacity and symptoms over 24 weeks. Future clinical trials could model the approach in SEQUOIA-HCM to evaluate the effect of potential therapies on the burden of oHCM. (Safety, Efficacy, and Quantitative Understanding of Obstruction Impact of Aficamten in HCM [SEQUOIA-HCM]; NCT05186818).

Mavacamten Treatment for Symptomatic Obstructive Hypertrophic Cardiomyopathy: Interim Results From the MAVA-LTE Study, EXPLORER-LTE Cohort

BACKGROUND

Data assessing the long-term safety and efficacy of mavacamten treatment for symptomatic obstructive hypertrophic cardiomyopathy are needed.

OBJECTIVES

The authors sought to evaluate interim results from the EXPLORER-Long Term Extension (LTE) cohort of MAVA-LTE (A Long-Term Safety Extension Study of Mavacamten in Adults Who Have Completed EXPLORER-HCM; NCT03723655).

METHODS

After mavacamten or placebo withdrawal at the end of the parent EXPLORER-HCM (Clinical Study to Evaluate Mavacamten [MYK-461] in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy; NCT03470545), patients could enroll in MAVA-LTE. Patients received mavacamten 5 mg once daily; adjustments were made based on site-read echocardiograms.

RESULTS

Between April 9, 2019, and March 5, 2021, 231 of 244 eligible patients (94.7%) enrolled in MAVA-LTE (mean age: 60 years; 39% female). At data cutoff (August 31, 2021) 217 (93.9%) remained on treatment (median time in study: 62.3 weeks; range: 0.3-123.9 weeks). At 48 weeks, patients showed improvements in left ventricular outflow tract (LVOT) gradients (mean change ± SD from baseline: resting: -35.6 ± 32.6 mm Hg; Valsalva: -45.3 ± 35.9 mm Hg), N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels (median: -480 ng/L; Q1-Q3: -1,104 to -179 ng/L), and NYHA functional class (67.5% improved by ≥1 class). LVOT gradients and NT-proBNP reductions were sustained through 84 weeks in patients who reached this timepoint. Over 315 patient-years of exposure, 8 patients experienced an adverse event of cardiac failure, and 21 patients had an adverse event of atrial fibrillation, including 11 with no prior history of atrial fibrillation. Twelve patients (5.2%) developed transient reductions in site-read echocardiogram left ventricular ejection fraction of <50%, resulting in temporary treatment interruption; all recovered. Ten patients discontinued treatment due to treatment-emergent adverse events.

CONCLUSIONS

Mavacamten treatment showed clinically important and durable improvements in LVOT gradients, NT-proBNP levels, and NYHA functional class, consistent with EXPLORER-HCM. Mavacamten treatment was well tolerated over a median 62-week follow-up.

Effect of Tafamidis on Cardiac Function in Patients With Transthyretin Amyloid Cardiomyopathy: A Post Hoc Analysis of the ATTR-ACT Randomized Clinical Trial

Importance

Tafamidis has been shown to improve survival in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) compared with placebo. However, its effect on cardiac function has not been fully characterized.

Objective

To examine the effect of tafamidis on cardiac function in patients with ATTR-CM.

Design, Setting, and Participants

This was an exploratory, post hoc analysis of the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT), a multicenter, international, double-blind, placebo-controlled phase 3 randomized clinical trial conducted from December 2013 to February 2018. The ATTR-ACT included 48 sites in 13 counties and enrolled patients aged 18 to 90 years with ATTR-CM. Data were analyzed from July 2018 to September 2023.

Intervention

Patients were randomized to tafamidis meglumine, 80 mg or 20 mg, or placebo for 30 months.

Main Outcomes and Measures

Patients were categorized based on left ventricular (LV) ejection fraction at enrollment as having heart failure with preserved ejection fraction (≥50%), mildly reduced ejection fraction (41% to 49%), or reduced ejection fraction (≤40%). Changes from baseline to month 30 in LV ejection fraction, LV stroke volume, LV global longitudinal strain, and the ratio of early mitral inflow velocity to septal and lateral early diastolic mitral annular velocity (E/e') were compared in patients receiving tafamidis, 80 mg, vs placebo.

Results

A total of 441 patients were randomized in ATTR-ACT, and 436 patients had available echocardiographic data. Of 436 included patients, 393 (90.1%) were male, and the mean (SD) age was 74 (7) years. A total of 220 (50.5%), 119 (27.3%), and 97 (22.2%) had heart failure with preserved, mildly reduced, and reduced LV ejection fraction, respectively. Over 30 months, there was less pronounced worsening in 4 of the echocardiographic measures in patients receiving tafamidis, 80 mg (n = 176), vs placebo (n = 177) (least squares mean difference: LV stroke volume, 7.02 mL; 95% CI, 2.55-11.49; P = .002; LV global longitudinal strain, -1.02%; 95% CI, -1.73 to -0.31; P = .005; septal E/e', -3.11; 95% CI, -5.50 to -0.72; P = .01; lateral E/e', -2.35; 95% CI, -4.01 to -0.69; P = .006).

Conclusions and Relevance

Compared with placebo, tafamidis, 80 mg, attenuated the decline of LV systolic and diastolic function over 30 months in patients with ATTR-CM. Approximately half of patients had mildly reduced or reduced LV ejection fraction at enrollment, suggesting that ATTR-CM should be considered as a possible diagnosis in patients with heart failure regardless of underlying LV ejection fraction.

Trial Registration

ClinicalTrials.gov Identifier: NCT01994889.

Tafamidis Efficacy Among Octogenarian Patients in the Phase 3 ATTR-ACT and Ongoing Long-Term Extension Study

BACKGROUND

Tafamidis was approved to treat patients with transthyretin amyloid cardiomyopathy (ATTR-CM) on the basis of findings from the phase 3 Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT).

OBJECTIVES

This study was a post hoc analysis exploring tafamidis efficacy in octogenarian patients.

METHODS

Analysis of patients aged <80 and ≥80 years in ATTR-ACT and its ongoing open-label long-term extension (LTE) study, where all patients receive tafamidis.

RESULTS

After 30 months in ATTR-ACT, least squares (LS) mean change from baseline in 6-minute walk test (6MWT) distance, N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration, and Kansas City Cardiomyopathy Questionnaire Overall Summary (KCCQ-OS) score were smaller (all P < 0.05) in patients aged ≥80 years treated with tafamidis (n = 51) vs placebo (n = 37). At the LTE study interim analysis, patients aged ≥80 years treated continuously with tafamidis had a smaller decline in KCCQ-OS score (P < 0.05) and trended toward longer median survival (45 vs 27 months; all-cause mortality HR: 0.6828 [95% CI: 0.4048-1.1517]; P = 0.1526) than those initially treated with placebo in ATTR-ACT. Similar efficacy was observed in patients aged <80 years in ATTR-ACT, including smaller LS mean change from baseline in 6MWT distance, NT-proBNP concentration, and KCCQ-OS score, and lower rate of cardiovascular-related hospitalizations with tafamidis (n = 125) vs placebo (n = 140). In the LTE study, patients aged <80 years treated continuously with tafamidis had a longer median survival (80 vs 41 months; HR = 0.4513 [95% CI: 0.3176-0.6413]; P < 0.0001) and a smaller decline in KCCQ-OS score than those initially treated with placebo.

CONCLUSIONS

The findings demonstrate tafamidis efficacy for patients with ATTR-CM both in those aged <80 and those aged ≥80 years. (Tafamidis in Transthyretin Cardiomyopathy Clinical Trial [ATTR-ACT]; NCT01994889/Long-term Safety of Tafamidis in Subjects With Transthyretin Cardiomyopathy; NCT02791230).

Titin domains with reduced core hydrophobicity cause dilated cardiomyopathy

The underlying genetic defect in most cases of dilated cardiomyopathy (DCM), a common inherited heart disease, remains unknown. Intriguingly, many patients carry single missense variants of uncertain pathogenicity targeting the giant protein titin, a fundamental sarcomere component. To explore the deleterious potential of these variants, we first solved the wild-type and mutant crystal structures of I21, the titin domain targeted by pathogenic variant p.C3575S. Although both structures are remarkably similar, the reduced hydrophobicity of deeply buried position 3575 strongly destabilizes the mutant domain, a scenario supported by molecular dynamics simulations and by biochemical assays that show no disulfide involving C3575. Prompted by these observations, we have found that thousands of similar hydrophobicity-reducing variants associate specifically with DCM. Hence, our results imply that titin domain destabilization causes DCM, a conceptual framework that not only informs pathogenicity assessment of gene variants but also points to therapeutic strategies counterbalancing protein destabilization.

Emery-Dreifuss muscular dystrophy Type 1 is associated with a high risk of malignant ventricular arrhythmias and end-stage heart failure

BACKGROUND AND AIMS

Emery-Dreifuss muscular dystrophy (EDMD) is caused by variants in EMD (EDMD1) and LMNA (EDMD2). Cardiac conduction defects and atrial arrhythmia are common to both, but LMNA variants also cause end-stage heart failure (ESHF) and malignant ventricular arrhythmia (MVA). This study aimed to better characterize the cardiac complications of EMD variants.

METHODS

Consecutively referred EMD variant-carriers were retrospectively recruited from 12 international cardiomyopathy units. MVA and ESHF incidences in male and female variant-carriers were determined. Male EMD variant-carriers with a cardiac phenotype at baseline (EMDCARDIAC) were compared with consecutively recruited male LMNA variant-carriers with a cardiac phenotype at baseline (LMNACARDIAC).

RESULTS

Longitudinal follow-up data were available for 38 male and 21 female EMD variant-carriers [mean (SD) ages 33.4 (13.3) and 43.3 (16.8) years, respectively]. Nine (23.7%) males developed MVA and five (13.2%) developed ESHF during a median (inter-quartile range) follow-up of 65.0 (24.3-109.5) months. No female EMD variant-carrier had MVA or ESHF, but nine (42.8%) developed a cardiac phenotype at a median (inter-quartile range) age of 58.6 (53.2-60.4) years. Incidence rates for MVA were similar for EMDCARDIAC and LMNACARDIAC (4.8 and 6.6 per 100 person-years, respectively; log-rank P = .49). Incidence rates for ESHF were 2.4 and 5.9 per 100 person-years for EMDCARDIAC and LMNACARDIAC, respectively (log-rank P = .09).

CONCLUSIONS

Male EMD variant-carriers have a risk of progressive heart failure and ventricular arrhythmias similar to that of male LMNA variant-carriers. Early implantable cardioverter defibrillator implantation and heart failure drug therapy should be considered in male EMD variant-carriers with cardiac disease.

Late gadolinium enhancement distribution patterns in non-ischaemic dilated cardiomyopathy: genotype-phenotype correlation

AIMS

Late gadolinium enhancement (LGE) is frequently found in patients with dilated cardiomyopathy (DCM); there is little information about its frequency and distribution pattern according to the underlying genetic substrate. We sought to describe LGE patterns according to genotypes and to analyse the risk of major ventricular arrhythmias (MVA) according to patterns.

METHODS AND RESULTS

Cardiac magnetic resonance findings and LGE distribution according to genetics were performed in a cohort of 600 DCM patients followed at 20 Spanish centres. After exclusion of individuals with multiple causative gene variants or with variants in infrequent DCM-causing genes, 577 patients (34% females, mean age 53.5 years, left ventricular ejection fraction 36.9 ± 13.9%) conformed to the final cohort. A causative genetic variant was identified in 219 (38%) patients, and 147 (25.5%) had LGE. Significant differences were found comparing LGE patterns between genes (P < 0.001). LGE was absent or rare in patients with variants in TNNT2, RBM20, and MYH7 (0, 5, and 20%, respectively). Patients with variants in DMD, DSP, and FLNC showed a predominance of LGE subepicardial patterns (50, 41, and 18%, respectively), whereas patients with variants in TTN, BAG3, LMNA, and MYBPC3 showed unspecific LGE patterns. The genetic yield differed according to LGE patterns. Patients with subepicardial, lineal midwall, transmural, and right ventricular insertion points or with combinations of LGE patterns showed an increased risk of MVA compared with patients without LGE.

CONCLUSION

LGE patterns in DCM have a specific distribution according to the affected gene. Certain LGE patterns are associated with an increased risk of MVA and with an increased yield of genetic testing.

A 15-year consolidated overview of data in over 6000 patients from the Transthyretin Amyloidosis Outcomes Survey (THAOS)

BACKGROUND

Transthyretin amyloidosis (ATTR amyloidosis) is a progressive, multisystemic, life-threatening disease resulting from the deposition of variant or wild-type (ATTRwt amyloidosis) transthyretin amyloid fibrils in various tissues and organs.

METHODS

Established in 2007, the Transthyretin Amyloidosis Outcomes Survey (THAOS) is the largest ongoing, global, longitudinal, observational study of patients with ATTR amyloidosis, including both hereditary and wild-type disease, and asymptomatic carriers of pathogenic TTR mutations. This analysis describes the baseline characteristics of symptomatic patients and asymptomatic gene carriers enrolled in THAOS since its inception in 2007 (data cutoff: August 1, 2022), providing a consolidated overview of 15-year data from the THAOS registry.

RESULTS

This analysis included 4428 symptomatic patients and 1707 asymptomatic gene carriers. The majority of symptomatic patients were male (70.8%) with a mean (standard deviation [SD]) age at symptom onset of 56.6 (17.9) years. Compared with the 14-year analysis, V30M remained the most prevalent genotype in Europe (62.2%), South America (78.6%), and Japan (74.2%) and ATTRwt remained most common in North America (56.2%). Relative to the 14-year analysis, there was an increase of mixed phenotype (from 16.6 to 24.5%) and a reduction of predominantly cardiac phenotype (from 40.7 to 31.9%). The proportion of patients with predominantly neurologic phenotype remained stable (from 40.1 to 38.7%). Asymptomatic gene carriers were 58.5% female with a mean age at enrollment of 41.9 years (SD 15.5).

CONCLUSIONS

This overview of > 6000 patients enrolled over 15 years in THAOS represents the largest registry analysis of ATTR amyloidosis to date and continues to emphasize the genotypic and phenotypic heterogeneity of the disease. Nearly a quarter of the symptomatic population within THAOS was mixed phenotype, underscoring the need for multidisciplinary management of ATTR amyloidosis.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00628745.

Improved long-term survival with tafamidis treatment in patients with transthyretin amyloid cardiomyopathy and severe heart failure symptoms

AIM

The value of disease-modifying therapies (such as tafamidis) in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) and severe heart failure symptoms has been debated. This study assessed long-term all-cause survival in patients with New York Heart Association (NYHA) class III symptoms in the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT) long-term extension (LTE) study.

METHODS AND RESULTS

At the baseline of ATTR-ACT, 55/176 (31.3%) patients receiving tafamidis 80 mg and 63/177 (35.6%) receiving placebo had NYHA class III symptoms. After 30 months of treatment, patients could join an ongoing LTE study to receive open-label tafamidis. In an interim analysis of the LTE study (August 2021), all-cause mortality was lower among patients with NYHA class III symptoms who received continuous tafamidis in ATTR-ACT and the LTE study (hazard ratio 0.64; 95% confidence interval 0.41-0.99; median follow-up: 60 months), as compared with those who received placebo in ATTR-ACT and tafamidis in the LTE study (median follow-up: 56 months). Similar findings were observed in patients with NYHA class I/II symptoms at baseline (0.50; 0.35-0.73; tafamidis 80 mg n = 121; placebo n = 114; median follow-up of 61 and 60 months, respectively).

CONCLUSION

We observed reduced all-cause mortality with continuous tafamidis treatment compared with delayed tafamidis treatment (placebo then tafamidis) in patients with NYHA class III symptoms at baseline over a median follow-up of ∼5 years. These findings demonstrate the value of tafamidis treatment in patients with ATTR-CM and severe heart failure symptoms, and emphasize the importance of early treatment.

CLINICAL TRIAL REGISTRATIONS

ClinicalTrials.gov NCT01994889 and NCT02791230.

World Heart Federation Consensus on Transthyretin Amyloidosis Cardiomyopathy (ATTR-CM)

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a progressive and fatal condition that requires early diagnosis, management, and specific treatment. The availability of new disease-modifying therapies has made successful treatment a reality. Transthyretin amyloid cardiomyopathy can be either age-related (wild-type form) or caused by mutations in the TTR gene (genetic, hereditary forms). It is a systemic disease, and while the genetic forms may exhibit a variety of symptoms, a predominant cardiac phenotype is often present. This document aims to provide an overview of ATTR-CM amyloidosis focusing on cardiac involvement, which is the most critical factor for prognosis. It will discuss the available tools for early diagnosis and patient management, given that specific treatments are more effective in the early stages of the disease, and will highlight the importance of a multidisciplinary approach and of specialized amyloidosis centres. To accomplish these goals, the World Heart Federation assembled a panel of 18 expert clinicians specialized in TTR amyloidosis from 13 countries, along with a representative from the Amyloidosis Alliance, a patient advocacy group. This document is based on a review of published literature, expert opinions, registries data, patients' perspectives, treatment options, and ongoing developments, as well as the progress made possible via the existence of centres of excellence. From the patients' perspective, increasing disease awareness is crucial to achieving an early and accurate diagnosis. Patients also seek to receive care at specialized amyloidosis centres and be fully informed about their treatment and prognosis.

International Consensus on Differential Diagnosis and Management of Patients With Danon Disease: JACC State-of-the-Art Review

Danon disease is a rare X-linked autophagic vacuolar cardioskeletal myopathy associated with severe heart failure that can be accompanied with extracardiac neurologic, skeletal, and ophthalmologic manifestations. It is caused by loss of function variants in the LAMP2 gene and is among the most severe and penetrant of the genetic cardiomyopathies. Most patients with Danon disease will experience symptomatic heart failure. Male individuals generally present earlier than women and die of either heart failure or arrhythmia or receive a heart transplant by the third decade of life. Herein, the authors review the differential diagnosis of Danon disease, diagnostic criteria, natural history, management recommendations, and recent advances in treatment of this increasingly recognized and extremely morbid cardiomyopathy.

Risks of Ventricular Arrhythmia and Heart Failure in Carriers of RBM20 Variants

BACKGROUND

Variants in RBM20 are reported in 2% to 6% of familial cases of dilated cardiomyopathy and may be associated with fatal ventricular arrhythmia and rapid heart failure progression. We sought to determine the risk of adverse events in RBM20 variant carriers and the impact of sex on outcomes.

METHODS

Consecutive probands and relatives carrying RBM20 variants were retrospectively recruited from 12 cardiomyopathy units. The primary end point was a composite of malignant ventricular arrhythmia (MVA) and end-stage heart failure (ESHF). MVA and ESHF end points were also analyzed separately and men and women compared. Left ventricular ejection fraction (LVEF) contemporary to MVA was examined. RBM20 variant carriers with left ventricular systolic dysfunction (RBM20LVSD) were compared with variant-elusive patients with idiopathic left ventricular systolic dysfunction.

RESULTS

Longitudinal follow-up data were available for 143 RBM20 variant carriers (71 men; median age, 35.5 years); 7 of 143 had an MVA event at baseline. Thirty of 136 without baseline MVA (22.0%) reached the primary end point, and 16 of 136 (11.8%) had new MVA with no significant difference between men and women (log-rank P=0.07 and P=0.98, respectively). Twenty of 143 (14.0%) developed ESHF (17 men and 3 women; log-rank P<0.001). Four of 10 variant carriers with available LVEF contemporary to MVA had an LVEF >35%. At 5 years, 15 of 67 (22.4%) RBM20LVSD versus 7 of 197 (3.6%) patients with idiopathic left ventricular systolic dysfunction had reached the primary end point (log-rank P<0.001). RBM20 variant carriage conferred a 6.0-fold increase in risk of the primary end point.

CONCLUSIONS

RBM20 variants are associated with a high risk of MVA and ESHF compared with idiopathic left ventricular systolic dysfunction. The risk of MVA in male and female RBM20 variant carriers is similar, but male sex is strongly associated with ESHF.

Case report: Alternative approach for management of refractory volume overload in heart failure: usefulness of venous leg compression

Background

Management of patients with refractory congestion, is one of the most important challenges in the field of heart failure (HF). Diuretic therapy remains the most widely used therapy to achieve euvolemia. However, some patients experience fluid overload despite the use of high-dose diuretics and new strategies to overcome diuretic resistance are needed.

Case Summary

We report an 85 years-old male patient admitted for decompensated HF with persistent tissue fluid overload (peripheral edema) for more than two weeks despite high dose of intravenous furosemide with the combination of other diuretics. At this point, we performed leg venous compression using elastic bandages for three days. After 72 h, edema disappeared, and additional weight loss was achieved (1 kg/day). No side effects were observed and the patient was discharged home euvolemic.

Conclusion

Venous leg compression may be an alternative therapy in patients with persistent tissue fluid overload resistant to diuretics.

Phase 1 Trial of Antibody NI006 for Depletion of Cardiac Transthyretin Amyloid

BACKGROUND

Transthyretin amyloid (ATTR) cardiomyopathy is a progressive and fatal disease caused by misfolded transthyretin. Despite advances in slowing disease progression, there is no available treatment that depletes ATTR from the heart for the amelioration of cardiac dysfunction. NI006 is a recombinant human anti-ATTR antibody that was developed for the removal of ATTR by phagocytic immune cells.

METHODS

In this phase 1, double-blind trial, we randomly assigned (in a 2:1 ratio) 40 patients with wild-type or variant ATTR cardiomyopathy and chronic heart failure to receive intravenous infusions of either NI006 or placebo every 4 weeks for 4 months. Patients were sequentially enrolled in six cohorts that received ascending doses (ranging from 0.3 to 60 mg per kilogram of body weight). After four infusions, patients were enrolled in an open-label extension phase in which they received eight infusions of NI006 with stepwise increases in the dose. The safety and pharmacokinetic profiles of NI006 were assessed, and cardiac imaging studies were performed.

RESULTS

The use of NI006 was associated with no apparent drug-related serious adverse events. The pharmacokinetic profile of NI006 was consistent with that of an IgG antibody, and no antidrug antibodies were detected. At doses of at least 10 mg per kilogram, cardiac tracer uptake on scintigraphy and extracellular volume on cardiac magnetic resonance imaging, both of which are imaging-based surrogate markers of cardiac amyloid load, appeared to be reduced over a period of 12 months. The median N-terminal pro-B-type natriuretic peptide and troponin T levels also seemed to be reduced.

CONCLUSIONS

In this phase 1 trial of the recombinant human antibody NI006 for the treatment of patients with ATTR cardiomyopathy and heart failure, the use of NI006 was associated with no apparent drug-related serious adverse events. (Funded by Neurimmune; NI006-101 ClinicalTrials.gov number, NCT04360434.).

AL Amyloidosis and Multiple Myeloma: A Complex Scenario in Which Cardiac Involvement Remains the Key Prognostic Factor

Monoclonal gammopathies (MGs) are a wide range of diseases that may evolve or progress over time. Comorbidity plays a critical role in this setting. The co-occurrence of two MGs is not a rare event. The evidence on the association of systemic light chain (AL) amyloidosis and multiple myeloma (MM) is scarce and controversial. Herein we aim to address this topic in a large series of patients of a referral center. All consecutive AL amyloidosis patients treated at our center from January 2005 to April 2023 were prospectively enrolled in a clinical and epidemiological registry. 141 patients diagnosed with AL amyloidosis were included, of which 7 (5%) had localized whereas 134 presented with systemic disease. The heart was the most frequently affected organ (90.3%). 25 patients (18.7%) fulfilled the IMWG diagnostic criteria of MM (AL/MM). Time-dependent association between AL and MM showed that the synchronous pattern is more frequent than the appearance of a second primary malignancy. The diagnostic delay was six months (m). Patients with AL/MM had a poorer median overall survival (OS) than AL-only patients (35.5 m, CI 95% 0-88.9, vs. 52.6 m, CI 95% 16.7-88.5), but this difference was not statistically significant. The prognosis in AL is dominated by the heart involvement, which is massive in this series. In our Cox regression model, only three prognostic variables remain as independent prognostic factors: age, N-terminal pro-brain natriuretic peptide (≥8500 ng/L), and undergoing an autologous stem cell transplant, whereas left ventricular ejection fraction shows a marginal effect. More and large studies focusing on the AL/MM association are needed to uncover the characteristics and prognostic impact of this association.

Phase 2 Study of Aficamten in Patients With Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

Left ventricular outflow tract (LVOT) obstruction is a major determinant of heart failure symptoms in obstructive hypertrophic cardiomyopathy (oHCM). Aficamten, a next-in-class cardiac myosin inhibitor, may lower gradients and improve symptoms in these patients.

OBJECTIVES

This study aims to evaluate the safety and efficacy of aficamten in patients with oHCM.

METHODS

Patients with oHCM and LVOT gradients ≥30 mm Hg at rest or ≥50 mm Hg with Valsalva were randomized 2:1 to receive aficamten (n = 28) or placebo (n = 13) in 2 dose-finding cohorts. Doses were titrated based on gradients and ejection fraction (EF). Safety and changes in gradient, EF, New York Heart Association functional class, and cardiac biomarkers were assessed over a 10-week treatment period and after a 2-week washout.

RESULTS

From baseline to 10 weeks, aficamten reduced gradients at rest (mean difference: -40 ± 27 mm Hg, and -43 ± 37 mm Hg in Cohorts 1 and 2, P = 0.0003 and P = 0.0004 vs placebo, respectively) and with Valsalva (-36 ± 27 mm Hg and -53 ± 44 mm Hg, P = 0.001 and <0.0001 vs placebo, respectively). There were modest reductions in EF (-6% ± 7.5% and -12% ± 5.9%, P = 0.007 and P < 0.0001 vs placebo, respectively). Symptomatic improvement in ≥1 New York Heart Association functional class was observed in 31% on placebo, and 43% and 64% on aficamten in Cohorts 1 and 2, respectively (nonsignificant). With aficamten, N-terminal pro-B-type natriuretic peptide was reduced (62% relative to placebo, P = 0.0002). There were no treatment interruptions and adverse events were similar between treatment arms.

CONCLUSIONS

Aficamten resulted in substantial reductions in LVOT gradients with most patients experiencing improvement in biomarkers and symptoms. These results highlight the potential of sarcomere-targeted therapy for treatment of oHCM.

Changing paradigm in the treatment of amyloidosis: From disease-modifying drugs to anti-fibril therapy

Cardiac amyloidosis is a rare, debilitating, and usually fatal disease increasingly recognized in clinical practice despite patients presenting with non-specific symptoms of cardiomyopathy. The current standard of care (SoC) focuses on preventing further amyloid formation and deposition, either with anti-plasma cell dyscrasia (anti-PCD) therapies in light-chain (AL) amyloidosis or stabilizers of transthyretin (TTR) in transthyretin amyloidosis (ATTR). The SoC is supplemented by therapies to treat the complications arising from organ dysfunction; for example, heart failure, arrhythmia, and proteinuria. Advancements in treatments have improved patient survival, especially for those whose disease is detected and for whom treatment is initiated at an early stage. However, there still are many unmet medical needs, particularly for patients with severe disease for whom morbidity and mortality remain high. There currently are no approved treatments to reverse amyloid infiltration and deplete the amyloid fibrils already deposited in organs, which can continue to cause progressive dysfunction. Anti-fibril therapies aimed at removing the deposited fibrils are being investigated for safety and efficacy in improving outcomes for patients with severe disease. However, there is no clinical evidence yet that removing deposited amyloid fibrils will improve organ function, thereby improving quality of life or extending life. Nevertheless, anti-fibril therapies are actively being investigated in clinical trials to evaluate their ability to complement and synergize with current SoC.

Frequency of hereditary transthyretin amyloidosis among elderly patients with transthyretin cardiomyopathy

AIMS

Transthyretin amyloid cardiomyopathy (ATTR-CM) is increasingly recognized as a cause of heart failure in the elderly. Although wild-type transthyretin amyloidosis is the most frequent form of ATTR-CM found in the elderly, hereditary transthyretin amyloidosis (ATTRv) can also occur. We sought to determine the prevalence of ATTRv among elderly ATTR-CM patients, identify predictors of ATTRv and evaluate the clinical consequences of positive genetic testing in this population.

METHODS AND RESULTS

Prevalence of ATTRv in elderly ATTR-CM patients (≥70 years) was assessed in a cohort of 300 consecutive ATTR-CM patients (median age 78 years at diagnosis, 82% ≥70 years, 16% female, 99% Caucasian). ATTRv was diagnosed in 35 (12%; 95% confidence interval [CI] 3.1-8.8) and 13 (5.3%; 95% CI 5.6-26.7) patients in the overall cohort and in those ≥70 years, respectively. Prevalence of ATTRv among elderly female patients with ATTR-CM was 13% (95% CI 2.1-23.5). Univariate analysis identified female sex (odds ratio [OR] 3.66; 95% CI 1.13-11.85; p = 0.03), black ancestry (OR 46.31; 95% CI 3.52-Inf; p = 0.005), eye symptoms (OR 6.64; 95% CI 1.20-36.73; p = 0.03) and polyneuropathy (OR 10.05; 95% CI 3.09-32.64; p < 0.001) as the only factors associated with ATTRv in this population. Diagnosis of ATTRv in elderly ATTR-CM patients allowed initiation of transthyretin-specific drug treatment in 5 individuals, genetic screening in 33 relatives from 13 families, and identification of 9 ATTRv asymptomatic carriers.

CONCLUSIONS

Hereditary transthyretin amyloidosis is present in a substantial number of ATTR-CM patients aged ≥70 years. Identification of ATTRv in elderly patients with ATTR-CM has clinical meaningful therapeutic and diagnostic implications. These results support routine genetic testing in patients with ATTR-CM regardless of age.

Phenotype and clinical outcomes of Glu89Lys hereditary transthyretin amyloidosis: a new endemic variant in Spain

BACKGROUND

The p.Glu109Lys variant (Glu89Lys) is a rare cause of hereditary transthyretin amyloidosis (ATTRv) for which clinical spectrum remains unresolved. We sought to describe the clinical characteristics and outcomes of ATTR Glu89Lys amyloidosis and assess a potential founder effect in Spain.

METHODS

Patients with the p.Glu109Lys ATTRv variant from 14 families were recruited at 7 centres. Demographics, complementary tests and clinical course were analysed. Haplotype analysis was performed in 7 unrelated individuals.

RESULTS

Thirty-eight individuals (13 probands, mean age 40.4 ± 13.1 years) were studied. After median follow-up of 5.1 years (IQR 1.7-9.6), 7 patients died and 7 required heart transplantation (median age at transplantation 50.5 years). Onset of cardiac and neurological manifestations occurred at a mean age of 48.4 and 46.8 years, respectively. Median survival from birth was 61.6 years and no individual survived beyond 65 years. Patients treated with disease-modifying therapies exhibited better prognosis (p < 0.001). Haplotype analysis revealed a common origin from an ancestor who lived ∼500 years ago in southeast Spain.

CONCLUSIONS

Glu89Lys ATTRv is a TTR variant with a founder effect in Spain. It is associated with near complete penetrance, early onset and mixed cardiac and neurologic phenotype. Patients have poor prognosis, particularly if not treated with disease-modifying therapies.

Non-invasive assessment of HFpEF in mouse models: current gaps and future directions

BACKGROUND

Heart failure (HF) with preserved ejection fraction (HFpEF) prevalence is increasing, and large clinical trials have failed to reduce mortality. A major reason for this outcome is the failure to translate results from basic research to the clinics. Evaluation of HFpEF in mouse models requires assessing three major key features defining this complex syndrome: the presence of a preserved left ventricular ejection fraction (LVEF), diastolic dysfunction, and the development of HF. In addition, HFpEF is associated with multiple comorbidities such as systemic arterial hypertension, chronic obstructive pulmonary disease, sleep apnea, diabetes, and obesity; thus, non-cardiac disorders assessment is crucial for a complete phenotype characterization. Non-invasive procedures present unquestionable advantages to maintain animal welfare and enable longitudinal analyses. However, unequivocally determining the presence of HFpEF using these methods remains challenging.

MAIN TEXT

Transthoracic echocardiography (TTE) represents an invaluable tool in HFpEF diagnosis, allowing evaluation of LVEF, diastolic dysfunction, and lung congestion in mice. Since conventional parameters used to evaluate an abnormal diastole like E/A ratio, isovolumic relaxation time, and E/e' may pose limitations in mice, including advanced TTE techniques to characterize cardiac motion, including an assessment under stress, will improve diagnosis. Patients with HFpEF also show electrical cardiac remodelling and therefore electrocardiography may add valuable information in mouse models to assess chronotropic incompetence and sinoatrial node dysfunction, which are major contributors to exercise intolerance. To complete the non-invasive diagnosis of HF, low aerobic exercise capacity and fatigue using exercise tests, impaired oxygen exchange using metabolic cages, and determination of blood biomarkers can be determined. Finally, since HFpEF patients commonly present non-cardiac pathological conditions, acquisition of systemic and pulmonary arterial pressures, blood glucose levels, and performing glucose tolerance and insulin resistance tests are required for a complete phenotyping.

CONCLUSION

Identification of reliable models of HFpEF in mice by using proper diagnosis tools is necessary to translate basic research results to the clinics. Determining the presence of several HFpEF indicators and a higher number of abnormal parameters will lead to more reliable evidence of HFpEF.

Natural History of MYH7-Related Dilated Cardiomyopathy

BACKGROUND

Variants in myosin heavy chain 7 (MYH7) are responsible for disease in 1% to 5% of patients with dilated cardiomyopathy (DCM); however, the clinical characteristics and natural history of MYH7-related DCM are poorly described.

OBJECTIVES

We sought to determine the phenotype and prognosis of MYH7-related DCM. We also evaluated the influence of variant location on phenotypic expression.

METHODS

We studied clinical data from 147 individuals with DCM-causing MYH7 variants (47.6% female; 35.6 ± 19.2 years) recruited from 29 international centers.

RESULTS

At initial evaluation, 106 (72.1%) patients had DCM (left ventricular ejection fraction: 34.5% ± 11.7%). Median follow-up was 4.5 years (IQR: 1.7-8.0 years), and 23.7% of carriers who were initially phenotype-negative developed DCM. Phenotypic expression by 40 and 60 years was 46% and 88%, respectively, with 18 patients (16%) first diagnosed at <18 years of age. Thirty-six percent of patients with DCM met imaging criteria for LV noncompaction. During follow-up, 28% showed left ventricular reverse remodeling. Incidence of adverse cardiac events among patients with DCM at 5 years was 11.6%, with 5 (4.6%) deaths caused by end-stage heart failure (ESHF) and 5 patients (4.6%) requiring heart transplantation. The major ventricular arrhythmia rate was low (1.0% and 2.1% at 5 years in patients with DCM and in those with LVEF of ≤35%, respectively). ESHF and major ventricular arrhythmia were significantly lower compared with LMNA-related DCM and similar to DCM caused by TTN truncating variants.

CONCLUSIONS

MYH7-related DCM is characterized by early age of onset, high phenotypic expression, low left ventricular reverse remodeling, and frequent progression to ESHF. Heart failure complications predominate over ventricular arrhythmias, which are rare.

Genetic Architecture of Acute Myocarditis and the Overlap With Inherited Cardiomyopathy

BACKGROUND

Acute myocarditis is an inflammatory condition that may herald the onset of dilated cardiomyopathy (DCM) or arrhythmogenic cardiomyopathy (ACM). We investigated the frequency and clinical consequences of DCM and ACM genetic variants in a population-based cohort of patients with acute myocarditis.

METHODS

This was a population-based cohort of 336 consecutive patients with acute myocarditis enrolled in London and Maastricht. All participants underwent targeted DNA sequencing for well-characterized cardiomyopathy-associated genes with comparison to healthy controls (n=1053) sequenced on the same platform. Case ascertainment in England was assessed against national hospital admission data. The primary outcome was all-cause mortality.

RESULTS

Variants that would be considered pathogenic if found in a patient with DCM or ACM were identified in 8% of myocarditis cases compared with <1% of healthy controls (P=0.0097). In the London cohort (n=230; median age, 33 years; 84% men), patients were representative of national myocarditis admissions (median age, 32 years; 71% men; 66% case ascertainment), and there was enrichment of rare truncating variants (tv) in ACM-associated genes (3.1% of cases versus 0.4% of controls; odds ratio, 8.2; P=0.001). This was driven predominantly by DSP-tv in patients with normal LV ejection fraction and ventricular arrhythmia. In Maastricht (n=106; median age, 54 years; 61% men), there was enrichment of rare truncating variants in DCM-associated genes, particularly TTN-tv, found in 7% (all with left ventricular ejection fraction <50%) compared with 1% in controls (odds ratio, 3.6; P=0.0116). Across both cohorts over a median of 5.0 years (interquartile range, 3.9-7.8 years), all-cause mortality was 5.4%. Two-thirds of deaths were cardiovascular, attributable to worsening heart failure (92%) or sudden cardiac death (8%). The 5-year mortality risk was 3.3% in genotype-negative patients versus 11.1% for genotype-positive patients (Padjusted=0.08).

CONCLUSIONS

We identified DCM- or ACM-associated genetic variants in 8% of patients with acute myocarditis. This was dominated by the identification of DSP-tv in those with normal left ventricular ejection fraction and TTN-tv in those with reduced left ventricular ejection fraction. Despite differences between cohorts, these variants have clinical implications for treatment, risk stratification, and family screening. Genetic counseling and testing should be considered in patients with acute myocarditis to help reassure the majority while improving the management of those with an underlying genetic variant.

Risk stratification in Arrhythmogenic Right Ventricular Cardiomyopathy: the impact of genotype on the 2019 ARVC risk calculator

Introduction

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is associated with sudden cardiac death (SCD). The 2019 ARVC risk model has been proposed as a method to quantify arrhythmic risk, but the impact of genotype its performance has not been addressed.

Purpose

To study arrhythmic outcomes in patients with ARVC and the performance of the 2019 ARVC risk model in predefined genetic subgroups.

Methods

This is an international, retrospective observational cohort study on consecutively evaluated patients with ARVC recruited from 17 centres in 7 countries. Inclusion criteria were: (i) a definite diagnosis of ARVC according to the 2010 Task Force Criteria; (ii) no history of sustained ventricular arrhythmia (VA) prior to first assessment at the participating centre; (iii) a follow up period of ≥1 month; (iv) age of diagnosis ≥14 years. Sustained ventricular arrhythmia (sustained ventricular tachycardia, appropriate implantable cardioverter defibrillator intervention, aborted SCD, or SCD) comprised the primary outcome (VA). Discriminative ability was assessed by Uno's concordance index (c-statistic) and calibration with the calibration plot slope. Fine-Gray regression was used to model the impact of clinical predictors on the arrhythmic outcome, in the context of competing risks (heart transplantation and non-arrhythmic death). The cumulative probability and 95% confidence intervals (95% CI) for the occurrence of an outcome were estimated using the Aalen-Johansen estimate in order to take into account competing risks.

Results

The study cohort comprised 554 ARVC patients. During a median follow-up of 6.0 [3.1,12.5] years, 100 patients (18%) experienced VA (Figure). Risk estimates for VA using the 2019 ARVC risk model showed good discriminative ability (c-statistic 0.75 (95% CI 0.70–0.81)) but with overestimation of risk (slope 0.46 (95% CI 0.33–0.63)). The ARVC risk model was compared in 4 gene groups: PKP2 (n=118, 21%); DSP (n=79, 14%); other desmosomal (n=59, 11%); and gene elusive (n=160, 29%). Discrimination and calibration were highest for PKP2 [c-statistic 0.83 (95% CI 0.75–0.91); calibration slope 0.67 (95% CI 0.40–1.04)] and lowest for the gene elusive group [c-statistic 0.65 (95% CI 0.57–0.74); calibration slope 0.26 (95% CI 0.06–0.49)]. Univariable analyses revealed variable performance of individual clinical risk markers in the different gene groups (see heatmap of hazard ratios and statistical significance in Figure). For example, RV dimensions and systolic function are significant risk markers in PKP2 but not in DSP patients and the opposite is true of LV systolic function (Figure).

Conclusion

The 2019 ARVC risk model performs reasonably well in gene positive ARVC, (particularly for PKP2) but is more limited in gene elusive patients. Genotype specific risk factors should be considered in ARVC patients.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation

Atrial fibrillation as a prognostic factor for all-cause mortality in patients with transthyretin amyloid cardiomyopathy

Introduction

Atrial fibrillation (afib) and flutter (aflutter) are among the most common manifestations of transthyretin amyloid cardiomyopathy (ATTR-CM) [1–3]. Studies have suggested that afib does not influence mortality [3–6]. Tafamidis was approved for the treatment of ATTR-CM based on the landmark, placebo-controlled, Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT), where all-cause mortality was a primary efficacy outcome [7].

Purpose

Evaluate whether afib/aflutter was prognostic for all-cause mortality in ATTR-ACT.

Methods

ATTR-ACT was a multinational, Phase 3, randomized study of patients with ATTR-CM receiving tafamidis meglumine (80 or 20 mg) or placebo over 30 months. This analysis describes the characteristics of patients with and without current/historical afib/aflutter at the baseline of ATTR-ACT. Current/historical afib/aflutter was then evaluated as an independent prognostic factor for all-cause mortality using Cox proportional hazards modelling.

Results

The 314/441 (71%) patients in ATTR-ACT with current/historical afib/aflutter were older, more commonly male, and White than those without (Table 1). A higher proportion of patients with current/historical afib/aflutter were NYHA class III and had a wild-type genotype than those without. Median 6MWT distance and the proportion of patients with preserved left ventricular ejection fraction (≥50%) were lower, GLS was less negative, and NT-proBNP and BUN were higher among those with current/historical afib/aflutter vs those without.

In ATTR-ACT, treatment, genotype, and NYHA class were included in the pre-specified Cox proportional hazards model assessing all-cause mortality. Once current/historical afib/aflutter was added to this model, all variables were found to be significant independent predictors of all-cause mortality (P&lt;0.05; Table 2). The risk of mortality was 45% higher (hazard ratio = 0.55 [95% CI: 0.37, 0.82]) among patients with current/historical afib/aflutter than in those without. In an expanded stepwise model selection analysis including 23 baseline demographic and clinical covariates, current/historical afib/aflutter was not a significant independent predictor. This model showed BUN and NT-proBNP concentrations, 6MWT distance, genotype, treatment, and GLS to be significant independent prognostic factors for all-cause mortality (P&lt;0.01; Table 2).

Conclusions

Patients in ATTR-ACT with ATTR-CM and current/historical afib/aflutter were older, more likely to be male, have a wild-type genotype, and more advanced heart failure than those without. A Cox model including treatment, genotype, and NYHA class identified current/historical afib/aflutter as a significant independent predictor of all-cause mortality. In an expanded stepwise selection model current/historical afib/aflutter remained important but was less prognostic compared to other covariates. Overall, these results demonstrate the importance of afib/aflutter in patients with ATTR-CM.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): This study was sponsored by Pfizer.

Therapeutic potential of wild type TMEM43 overexpression in a mouse model of arrhythmogenic cardiomyopathy type 5

Background and purpose

Arrhythmogenic cardiomyopathy type 5 (ACM5) is the most severe subtype of arrhythmogenic cardiomyopathy, caused by a point mutation in TMEM43 (p.S358L). Pathologically, the disease is characterised by dilation of the cardiac chambers and fibro-fatty replacement of the myocardium, which results in heart failure and sudden cardiac death. The function of TMEM43 and the molecular mechanism underlying ACM5 are very poorly understood, precluding the development of effective therapeutic options.

We have previously observed the interaction between the wild-type (WT) and pS358L forms of TMEM43, suggesting that WT-TMEM43 could quench the detrimental effects of the mutant protein by forming a heterodimer. Therefore, we propose that the overexpression of WT-TMEM43 could be beneficial for ACM5 progression.

Methods and results

Using our transgenic mouse models overexpressing either WT- or pS358L-TMEM43, we have generated a double transgenic mouse overexpressing both forms of the protein. The functional effects were analysed by echocardiography and electrocardiography at 5, 16 and 24 weeks of age. The lifespan of double transgenic (DT) mice increased by 10 weeks compared to mice overexpressing the mutant TMEM43 (p&lt;0.0001). Echocardiography results show an improved systolic function of both ventricles, as observed by an increased left ventricular ejection fraction (LVEF, p&lt;0.001) and tricuspid annular plane systolic excursion (TAPSE, p&lt;0.01), which is already evident at 16 weeks of age. This is accompanied by an improvement in cardiac conduction, with a reduced p wave duration (p&lt;0.001) and QRS duration (p&lt;0.001) and increased QRS amplitude (p&lt;0.0001) in DT mice compared to the mutant mice. In addition, histological analysis of heart samples shows a reduced fibrotic content in the myocardium of DT mice at 24 weeks of age (p&lt;0.0001). Furthermore, the delayed raise in serum cardiac troponin I levels suggests cardiomyocyte necrosis is also delayed in the therapeutic mouse model.

Conclusion

Overall, this data provides evidence that an overexpression of WT-TMEM43 delays the onset of ACM5 phenotype and could potentially be a novel therapeutic approach for ACM5.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Spanish Ministry of Science and Innovation

Natural history of MYH7-related dilated cardiomyopathy

Background

Variants in MYH7 are responsible for disease in 1–5% of patients with dilated cardiomyopathy (DCM); however, the clinical characteristics and natural history of MYH7-related DCM are poorly described.

Objectives

We sought to determine the phenotype and prognosis of MYH7-related DCM. We also evaluated the influence of variant location on phenotypic expression.

Methods

We studied clinical data from 147 individuals with DCM-causing MYH7 variants (47.6% females, 35.6±19.2 years) recruited from 29 international centers.

Results

At initial evaluation, 106 patients (72.1%) had DCM (LVEF 34.5±11.7%). Median follow-up was 4.5 years (interquartile range: 1.7–8.0). 23.7% carriers who were initially phenotype-negative developed DCM. Disease penetrance by 40 and 60 years was 46% and 88%, respectively, with 18 patients (16%) first diagnosed at &lt;18 years. Thirty-six percent of patients with DCM met imaging criteria for LV non-compaction. During follow-up, 28% showed left ventricular reverse remodeling (LVRR). Overall incidence of end-stage heart failure (heart transplantation or heart failure related death) was 11.6% at 5 years. Overall major ventricular arrhythmia rate was low (1.0% at 5 years) even among patients with LVEF ≤35% (2.1% at 5 years). LV non-compaction was more prevalent in patients with variants in head domain (S1) (44.2%) compared with other domains (P&lt;0.001). No differences among domain groups were found regarding LVRR, major ventricular arrhythmias or end-stage heart failure.

Conclusions

MYH7-related DCM is characterized by early age of onset, high penetrance, low rate of LVRR, and frequent progression to ESHF. Heart failure complications predominate over ventricular arrhythmias, even among patients with severe systolic disfunction.

Funding Acknowledgement

Type of funding sources: None.

Influence of sex on cardiovascular outcomes in RBM20 variant carriers

Background

Variants in the RBM20 gene cause dilated cardiomyopathy and may be associated with a poor prognosis.

Objectives

To determine disease penetrance, the risk of adverse events and the influence of sex on outcomes in RBM20 variant carriers.

Methods

Consecutive probands and relatives carrying pathogenic or likely pathogenic RBM20 variants were retrospectively recruited from 12 cardiomyopathy units. The primary endpoint was a composite of malignant ventricular arrhythmia (MVA) and end-stage heart failure (ESHF). MVA and ESHF endpoints were also analysed separately and males and females compared.

Results

Longitudinal follow-up data were available for 163 RBM20 variant carriers (82 male, median age 36.5 years, median follow-up 77.6 months). 10/163 had an MVA event at baseline. 30/153 without baseline MVA (19.6%) reached the primary endpoint with a trend towards worse outcomes in males (p=0.08). 16/153 (10.5%) had new MVA with no difference between males and females (p=0.92). 20/163 (12.2%) developed ESHF (17 males and 3 females; p&lt;0.001).

By the end of follow-up, 114 patients (70%) had either left ventricular systolic dysfunction (LVSD) or had experienced MVA. 22 patients received a first diagnosis of LVSD during follow-up. Disease penetrance in individuals over 40 years of age was 78.5% by last evaluation.

Eleven patients that reached the MVA endpoint had a left ventricular ejection fraction (LVEF) available within 6 months of the event. Median [IQR] contemporary LVEF was 30% [23.75, 40%]. 5/11 patients had a contemporary LVEF &gt;35%. 1/11 had a contemporary LVEF &gt;45% (a female, 1st degree relative presenting with sustained ventricular tachycardia and an LVEF of 65%).

Conclusions

RBM20 variants are highly penetrant. The risk of MVA in male and female RBM20 variant carriers is similar but male sex is strongly associated with ESHF. MVA events occur in patients with LVEF &gt;35%.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation Clinical Research Training Fellowship

Clinical Risk Score to Predict Pathogenic Genotypes in Patients With Dilated Cardiomyopathy

BACKGROUND

Although genotyping allows family screening and influences risk-stratification in patients with nonischemic dilated cardiomyopathy (DCM) or isolated left ventricular systolic dysfunction (LVSD), its result is negative in a significant number of patients, limiting its widespread adoption.

OBJECTIVES

This study sought to develop and externally validate a score that predicts the probability for a positive genetic test result (G+) in DCM/LVSD.

METHODS

Clinical, electrocardiogram, and echocardiographic variables were collected in 1,015 genotyped patients from Spain with DCM/LVSD. Multivariable logistic regression analysis was used to identify variables independently predicting G+, which were summed to create the Madrid Genotype Score. The external validation sample comprised 1,097 genotyped patients from the Maastricht and Trieste registries.

RESULTS

A G+ result was found in 377 (37%) and 289 (26%) patients from the derivation and validation cohorts, respectively. Independent predictors of a G+ result in the derivation cohort were: family history of DCM (OR: 2.29; 95% CI: 1.73-3.04; P < 0.001), low electrocardiogram voltage in peripheral leads (OR: 3.61; 95% CI: 2.38-5.49; P < 0.001), skeletal myopathy (OR: 3.42; 95% CI: 1.60-7.31; P = 0.001), absence of hypertension (OR: 2.28; 95% CI: 1.67-3.13; P < 0.001), and absence of left bundle branch block (OR: 3.58; 95% CI: 2.57-5.01; P < 0.001). A score containing these factors predicted a G+ result, ranging from 3% when all predictors were absent to 79% when ≥4 predictors were present. Internal validation provided a C-statistic of 0.74 (95% CI: 0.71-0.77) and a calibration slope of 0.94 (95% CI: 0.80-1.10). The C-statistic in the external validation cohort was 0.74 (95% CI: 0.71-0.78).

CONCLUSIONS

The Madrid Genotype Score is an accurate tool to predict a G+ result in DCM/LVSD.

Importance of genotype for risk stratification in arrhythmogenic right ventricular cardiomyopathy using the 2019 ARVC risk calculator

AIMS

To study the impact of genotype on the performance of the 2019 risk model for arrhythmogenic right ventricular cardiomyopathy (ARVC).

METHODS AND RESULTS

The study cohort comprised 554 patients with a definite diagnosis of ARVC and no history of sustained ventricular arrhythmia (VA). During a median follow-up of 6.0 (3.1,12.5) years, 100 patients (18%) experienced the primary VA outcome (sustained ventricular tachycardia, appropriate implantable cardioverter defibrillator intervention, aborted sudden cardiac arrest, or sudden cardiac death) corresponding to an annual event rate of 2.6% [95% confidence interval (CI) 1.9-3.3]. Risk estimates for VA using the 2019 ARVC risk model showed reasonable discriminative ability but with overestimation of risk. The ARVC risk model was compared in four gene groups: PKP2 (n = 118, 21%); desmoplakin (DSP) (n = 79, 14%); other desmosomal (n = 59, 11%); and gene elusive (n = 160, 29%). Discrimination and calibration were highest for PKP2 and lowest for the gene-elusive group. Univariable analyses revealed the variable performance of individual clinical risk markers in the different gene groups, e.g. right ventricular dimensions and systolic function are significant risk markers in PKP2 but not in DSP patients and the opposite is true for left ventricular systolic function.

CONCLUSION

The 2019 ARVC risk model performs reasonably well in gene-positive ARVC (particularly for PKP2) but is more limited in gene-elusive patients. Genotype should be included in future risk models for ARVC.

Sex Differences in Wild-Type Transthyretin Amyloidosis: An Analysis from the Transthyretin Amyloidosis Outcomes Survey (THAOS)

Introduction

Wild-type transthyretin amyloidosis (ATTRwt amyloidosis) is a progressive disease resulting from the accumulation of wild-type transthyretin (TTR) amyloid fibrils, and is diagnosed primarily in males. This analysis examined sex differences in patients with ATTRwt amyloidosis from the Transthyretin Amyloidosis Outcomes Survey (THAOS).

Methods

THAOS is an ongoing, global, longitudinal, observational survey of patients with transthyretin amyloidosis, including both inherited and wild-type disease, and asymptomatic carriers of TTR mutations. THAOS data were analyzed to identify potential differences in demographic and clinical characteristics between males and females with ATTRwt amyloidosis (data cutoff: August 1, 2021).

Results

Of 1386 patients with ATTRwt amyloidosis, 84 (6%) were female and 1302 (94%) were male. Females had a higher median age at enrollment (80 vs. 78 years; p = 0.002) and symptom onset (75 vs. 73 years; p = 0.045) than males. Mean left ventricular (LV) ejection fraction was higher (53% vs. 48%; p = 0.001) and mean LV diastolic diameter lower (42 vs. 46 mm; p < 0.001) in females versus males, but sex was not identified as a predictor of LV mean wall thickness adjusted for height (beta coefficient − 0.22; p = 0.460) or a predominantly cardiac phenotype (odds ratio 1.60; p = 0.191). Modified polyneuropathy disability scores differed between groups (p < 0.001), with a larger proportion of scores ≥ IIIa among females (23% vs. 7%).

Conclusions

Females with ATTRwt amyloidosis in THAOS tended to present at a later age and showed signs of less severe cardiac impairment and more severe walking impairment.

Trial Registration

ClinicalTrials.gov: NCT00628745.

Role of Early Assesment of Diuresis and Natriuresis in Detecting In-Hospital Diuretic Resistance in Acute Heart Failure

Background and Purpose: European Guidelines recommend early evaluation of diuresis and natriuresis after the first administration of diuretic to identify patients with insufficient diuretic response during acute heart failure. The aim of this work is to evaluate the prevalence and characteristics of patients with insufficient diuretic response according to this new algorithm.

Methods: Prospective observational single centre study of consecutive patients with acute heart failure and congestive signs. Clinical evaluation, echocardiography and blood tests were performed. Diuretic naïve patients received 40 mg of intravenous furosemide. Patients on an oupatient diuretic regimen received 2 times the ambulatory dose. The diuresis volume was assessed 6 h after the first loop diuretic administration, and a spot urinary sample was taken after 2 h. Insufficient diuretic response was defined as natriuresis <70 mEq/L or diuresis volume <600 ml.

Results: From January 2020 to December 2021, 73 patients were included (59% males, median age 76 years). Of these, 21 patients (28.8%, 95%CI 18.4; 39.2) had an insufficient diuretic response. Diuresis volume was <600 ml in 13 patients (18.1%), and 12 patients (16.4%) had urinary sodium <70 mEq/L. These patients had lower systolic blood pressure, worse glomerular filtration rate, and higher aldosterone levels. Ambulatory furosemide dose was also higher. These patients required more frequently thiazides and inotropes during admission.

Conclusion: The diagnostic algorithm based on diuresis and natriuresis was able to detect up to 29% of patients with insufficient diuretic response, who showed some characteristics of more advanced disease.

Relationship Between Maximal Left Ventricular Wall Thickness and Sudden Cardiac Death in Childhood Onset Hypertrophic Cardiomyopathy

BACKGROUND

Maximal left ventricular wall thickness (MLVWT) is a risk factor for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). In adults, the severity of left ventricular hypertrophy has a nonlinear relationship with SCD, but it is not known whether the same complex relationship is seen in childhood. The aim of this study was to describe the relationship between left ventricular hypertrophy and SCD risk in a large international pediatric HCM cohort.

METHODS

The study cohort comprised 1075 children (mean age, 10.2 years [±4.4]) diagnosed with HCM (1-16 years) from the International Paediatric Hypertrophic Cardiomyopathy Consortium. Anonymized, noninvasive clinical data were collected from baseline evaluation and follow-up, and 5-year estimated SCD risk was calculated (HCM Risk-Kids).

RESULTS

MLVWT Z score was <10 in 598 (58.1%), ≥10 to <20 in 334 (31.1%), and ≥20 in 143 (13.3%). Higher MLVWT Z scores were associated with heart failure symptoms, unexplained syncope, left ventricular outflow tract obstruction, left atrial dilatation, and nonsustained ventricular tachycardia. One hundred twenty-two patients (71.3%) with MLVWT Z score ≥20 had coexisting risk factors for SCD. Over a median follow-up of 4.9 years (interquartile range, 2.3-9.3), 115 (10.7%) had an SCD event. Freedom from SCD event at 5 years for those with MLVWT Z scores <10, ≥10 to <20, and ≥20 was 95.6%, 87.4%, and 86.0, respectively. The estimated SCD risk at 5 years had a nonlinear, inverted U-shaped relationship with MLVWT Z score, peaking at Z score +23. The presence of coexisting risk factors had a summative effect on risk.

CONCLUSIONS

In children with HCM, an inverted U-shaped relationship exists between left ventricular hypertrophy and estimated SCD risk. The presence of additional risk factors has a summative effect on risk. While MLVWT is important for risk stratification, it should not be used either as a binary variable or in isolation to guide implantable cardioverter defibrillator implantation decisions in children with HCM.