Characterization and natural history of patients with LMNA-related dilated cardiomyopathy in the phase 3 REALM-DCM trial.

AIMS: LMNA-related dilated cardiomyopathy (DCM) is a rare disease with an incompletely defined phenotype. The phase 3 REALM-DCM trial evaluated a potential disease-modifying therapy for LMNA-related DCM but was terminated due to futility without safety concern. This study utilized pooled data from REALM-DCM to descriptively characterize the phenotype and progression of LMNA-related DCM in a contemporary cohort of patients using common heart failure (HF) measures. METHODS: REALM-DCM enrolled patients with stable LMNA-related DCM, an implanted cardioverter defibrillator or cardiac resynchronization therapy defibrillator, and New York Heart Association (NYHA) Class II/III HF symptoms. RESULTS: Between 2018 and 2022, 77 patients took part in REALM-DCM. The median patient age was 53 years (range: 23-72), and 57% were male. Overall, 88% of patients had a pathogenic or likely pathogenic LMNA variant, and 12% had a variant of uncertain significance with a concordant phenotype. Among patients with confirmed sequencing, 55% had a missense variant. Atrial fibrillation was present in 60% of patients; 79% of all patients had NYHA Class II and 21% had NYHA Class III HF symptoms at baseline. Median (range) left ventricular ejection fraction (LVEF), 6 min walk test (6MWT) distance, Kansas City Cardiomyopathy Questionnaire Overall Summary (KCCQ-OS) score and N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration at baseline were 42% (23-62), 403 m (173-481), 67 (18-97) and 866 pg/mL (57-5248), respectively. LVEF, 6MWT distance and KCCQ-OS score were numerically lower in patients who had NYHA Class III versus II symptoms at baseline (LVEF: 38% vs. 43%; 6MWT distance: 326 vs. 413 m; and KCCQ-OS score: 43 vs. 70), whereas NT-proBNP concentration was higher (1216 vs. 799 pg/mL). Median follow-up was 73 weeks (range: 0.4-218; 73 in NYHA Class II and 75 in NYHA Class III). Patients displayed variable change from baseline in 6MWT, KCCQ-OS and NT-proBNP values during follow-up. Overall, 25% of patients experienced ventricular tachycardia, and 8% had ventricular fibrillation. Ten (13%) patients met the composite endpoint of worsening HF (adjudicated HF-related hospitalization or urgent care visit) or all-cause death; six had NYHA Class II and four had NYHA Class III at baseline. All-cause mortality occurred in 6 (8%) patients; three had NYHA Class II and three had NYHA Class III symptoms at baseline. CONCLUSIONS: Findings confirm the significant morbidity and mortality associated with LMNA-related DCM despite the standard of care management. Typical measures of HF, including 6MWT distance, KCCQ-OS score and NT-proBNP concentration, were variable but correlated with NYHA class. An unmet treatment need remains among patients with LMNA-related DCM. NCT03439514.

Safety and efficacy of aficamten in patients with non-obstructive hypertrophic cardiomyopathy: A 36-week analysis from FOREST-HCM.

AIMS: The aim of this study was to report safety and efficacy of aficamten in patients with non-obstructive hypertrophic cardiomyopathy (nHCM) over 36 weeks in the ongoing FOREST-HCM trial. METHODS AND RESULTS: Patients were started on aficamten 5 mg daily, with doses adjusted in 5-mg increments (5-20 mg) at ≥2-week intervals according to site-read left ventricular ejection fraction (LVEF). Aficamten dose was increased if LVEF ≥55%, maintained if LVEF 50-54%, decreased if LVEF 40-<50%, and temporarily interrupted if LVEF <40%. Safety and efficacy were assessed over 36 weeks. Overall, 34 patients were enrolled (mean age 57.2 ± 15.3 years, 62% female, 41% in New York Heart Association [NYHA] class III). Over 36 weeks, 82.3% achieved 15-20 mg daily dose and there was a modest reduction in LVEF by -4.3% ± 5.2 from 70% ± 6.1 (p < 0.0001). At Week 36, NYHA class improved by ≥1 class in 27 (79.4%) patients. Mean Kansas City Cardiomyopathy Questionnaire clinical summary score improved by 13.8 ± 12.5 points relative to baseline. Median (interquartile range) levels of N-terminal pro-B-type natriuretic peptide were significantly improved from baseline (-665.5 pg/ml [-1244.0, -232.0]; p < 0.0001), while high-sensitivity cardiac troponin I was unchanged (-2.7 ng/L [-11.3, 1.6]; p = 0.25). There were no drug discontinuations due to adverse events. LVEF <50% occurred in 2 (5.9%) patients, one following pulmonary vein isolation and one associated with atrial fibrillation. CONCLUSIONS: Over 36 weeks, aficamten appeared safe and effective in the studied patients with nHCM.

Antithrombotic properties of Tafamidis: An additional protective effect for transthyretin amyloid cardiomyopathy patients.

INTRODUCTION: Tafamidis is a molecular chaperone that stabilizes the transthyretin (TTR) homo-tetramer, preventing its dissociation and consequent deposition as amyloid fibrils in organ tissues. Tafamidis reduces mortality and the incidence of hospitalization for cardiovascular causes in patients with TTR amyloid (ATTR) cardiomyopathy. As ATTR cardiomyopathy is associated with a high risk of thromboembolic complications, we hypothesized that tafamidis may have a direct ancillary anti-thrombotic effect. METHODS: Primary human aortic endothelial cells (HAECs) were treated with tafamidis at clinically relevant concentrations and with plasma of patients, before and after the initiation of treatment with tafamidis. The expression of TF was induced by incubation with Tumor Necrosis Factor α (TNFα). Intracellular expression of tissue factor (TF) was measured by western blot. TF activity was measured by a colorimetric assay. Gene expressions of TF were measured by quantitative polymerase chain reaction. RESULTS: Treatment with tafamidis dose-dependently reduced the expression and activity of TNFα-induced TF. This effect was confirmed in cells treated with patients' plasma. Signal Transducer and Activator of Transcription 3 (STAT3) phosphorylation was significantly inhibited by tafamidis. Incubation of HAECs with tafamidis and the STAT3 activator colivelin partially rescued the expression of TF. CONCLUSIONS: Treatment with tafamidis lowers the thrombotic potential in human primary endothelial cells by reducing TF expression and activity. This previously unknown off-target effect may provide a novel mechanistic explanation for the lower number of thromboembolic complications in ATTR cardiomyopathy patients treated with tafamidis.

REALM-DCM: A Phase 3, Multinational, Randomized, Placebo-Controlled Trial of ARRY-371797 in Patients With Symptomatic LMNA-Related Dilated Cardiomyopathy.

BACKGROUND: LMNA (lamin A/C)-related dilated cardiomyopathy is a rare genetic cause of heart failure. In a phase 2 trial and long-term extension, the selective p38α MAPK (mitogen-activated protein kinase) inhibitor, ARRY-371797 (PF-07265803), was associated with an improved 6-minute walk test at 12 weeks, which was preserved over 144 weeks. METHODS: REALM-DCM (NCT03439514) was a phase 3, randomized, double-blind, placebo-controlled trial in patients with symptomatic LMNA-related dilated cardiomyopathy. Patients with confirmed LMNA variants, New York Heart Association class II/III symptoms, left ventricular ejection fraction ≤50%, implanted cardioverter-defibrillator, and reduced 6-minute walk test distance were randomized to ARRY-371797 400 mg twice daily or placebo. The primary outcome was a change from baseline at week 24 in the 6-minute walk test distance using stratified Hodges-Lehmann estimation and the van Elteren test. Secondary outcomes using similar methodology included change from baseline at week 24 in the Kansas City Cardiomyopathy Questionnaire-physical limitation and total symptom scores, and NT-proBNP (N-terminal pro-B-type natriuretic peptide) concentration. Time to a composite outcome of worsening heart failure or all-cause mortality and overall survival were evaluated using Kaplan-Meier and Cox proportional hazards analyses. RESULTS: REALM-DCM was terminated after a planned interim analysis suggested futility. Between April 2018 and October 2022, 77 patients (aged 23-72 years) received ARRY-371797 (n=40) or placebo (n=37). No significant differences (P>0.05) between groups were observed in the change from baseline at week 24 for all outcomes: 6-minute walk test distance (median difference, 4.9 m [95% CI, -24.2 to 34.1]; P=0.82); Kansas City Cardiomyopathy Questionnaire-physical limitation score (2.4 [95% CI, -6.4 to 11.2]; P=0.54); Kansas City Cardiomyopathy Questionnaire-total symptom score (5.3 [95% CI, -4.3 to 14.9]; P=0.48); and NT-proBNP concentration (-339.4 pg/mL [95% CI, -1131.6 to 452.7]; P=0.17). The composite outcome of worsening heart failure or all-cause mortality (hazard ratio, 0.43 [95% CI, 0.11-1.74]; P=0.23) and overall survival (hazard ratio, 1.19 [95% CI, 0.23-6.02]; P=0.84) were similar between groups. No new safety findings were observed. CONCLUSIONS: Findings from REALM-DCM demonstrated futility without safety concerns. An unmet treatment need remains among patients with LMNA-related dilated cardiomyopathy. REGISTRATION: URL: https://classic.clinicaltrials.gov; Unique Identifiers: NCT03439514, NCT02057341, and NCT02351856.

Distal Ventricular Pacing for Drug-Refractory Mid-Cavity Obstructive Hypertrophic Cardiomyopathy: A Randomized, Placebo-Controlled Trial of Personalized Pacing.

BACKGROUND: Patients with refractory, symptomatic left ventricular (LV) mid-cavity obstructive (LVMCO) hypertrophic cardiomyopathy have few therapeutic options. Right ventricular pacing is associated with modest hemodynamic and symptomatic improvement, and LV pacing pilot data suggest therapeutic potential. We hypothesized that site-specific pacing would reduce LVMCO gradients and improve symptoms. METHODS: Patients with symptomatic-drug-refractory LVMCO were recruited for a randomized, blinded trial of personalized prescription of pacing (PPoP). Multiple LV and apical right ventricular pacing sites were assessed during an invasive hemodynamic study of multisite pacing. Patient-specific pacing-site and atrioventricular delays, defining PPoP, were selected on the basis of LVMCO gradient reduction and acceptable pacing parameters. Patients were randomized to 6 months of active PPoP or backup pacing in a crossover design. The primary outcome examined invasive gradient change with best-site pacing. Secondary outcomes assessed quality of life and exercise following randomization to PPoP. RESULTS: A total of 17 patients were recruited; 16 of whom met primary end points. Baseline New York Heart Association was 3±0.6, despite optimal medical therapy. Hemodynamic effects were assessed during pacing at the right ventricular apex and at a mean of 8 LV sites. The gradients in all 16 patients fell with pacing, with maximum gradient reduction achieved via LV pacing in 14 (88%) patients and right ventricular apex in 2. The mean baseline gradient of 80±29 mm Hg fell to 31±21 mm Hg with best-site pacing, a 60% reduction (P<0.0001). One cardiac vein perforation occurred in 1 case, and 15 subjects entered crossover; 2 withdrawals occurred during crossover. Of the 13 completing crossover, 9 (69%) chose active pacing in PPoP configuration as preferred setting. PPoP was associated with improved 6-minute walking test performance (328.5±99.9 versus 285.8±105.5 m; P=0.018); other outcome measures also indicated benefit with PPoP. CONCLUSIONS: In a randomized placebo-controlled trial, PPoP reduces obstruction and improves exercise performance in severely symptomatic patients with LVMCO. REGISTRATION: URL: https://clinicaltrials.gov/study; Unique Identifier: NCT03450252.

Genetics of hypertrophic cardiomyopathy: established and emerging implications for clinical practice.

Pathogenic variation in genes encoding proteins of the cardiac sarcomere is responsible for 30%-40% of cases of hypertrophic cardiomyopathy. The main clinical utility of genetic testing is to provide diagnostic confirmation and facilitation of family screening. It also assists in the detection of aetiologies, which require distinct monitoring and treatment approaches. Other clinical applications, including the use of genetic information to inform risk prediction models, have been limited by the challenge of establishing robust genotype-phenotype correlations with actionable consequences, but new data on the interaction between rare and common genetic variation, as well as the emergence of therapies targeting disease-specific pathogenic mechanisms, herald a new era for genetic testing in routine practice.

Novel Multiplexed Plasma Biomarker Panel Has Diagnostic and Prognostic Potential in Children With Hypertrophic Cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is defined clinically by pathological left ventricular hypertrophy. We have previously developed a plasma proteomics biomarker panel that correlates with clinical markers of disease severity and sudden cardiac death risk in adult patients with HCM. The aim of this study was to investigate the utility of adult biomarkers and perform new discoveries in proteomics for childhood-onset HCM. METHODS: Fifty-nine protein biomarkers were identified from an exploratory plasma proteomics screen in children with HCM and augmented into our existing multiplexed targeted liquid chromatography-tandem/mass spectrometry-based assay. The association of these biomarkers with clinical phenotypes and outcomes was prospectively tested in plasma collected from 148 children with HCM and 50 healthy controls. Machine learning techniques were used to develop novel pediatric plasma proteomic biomarker panels. RESULTS: Four previously identified adult HCM markers (aldolase fructose-bisphosphate A, complement C3a, talin-1, and thrombospondin 1) and 3 new markers (glycogen phosphorylase B, lipoprotein a and profilin 1) were elevated in pediatric HCM. Using supervised machine learning applied to training (n=137) and validation cohorts (n=61), this 7-biomarker panel differentiated HCM from healthy controls with an area under the curve of 1.0 in the training data set (sensitivity 100% [95% CI, 95-100]; specificity 100% [95% CI, 96-100]) and 0.82 in the validation data set (sensitivity 75% [95% CI, 59-86]; specificity 88% [95% CI, 75-94]). Reduced circulating levels of 4 other peptides (apolipoprotein L1, complement 5b, immunoglobulin heavy constant epsilon, and serum amyloid A4) found in children with high sudden cardiac death risk provided complete separation from the low and intermediate risk groups and predicted mortality and adverse arrhythmic outcomes (hazard ratio, 2.04 [95% CI, 1.0-4.2]; P=0.044). CONCLUSIONS: In children, a 7-biomarker proteomics panel can distinguish HCM from controls with high sensitivity and specificity, and another 4-biomarker panel identifies those at high risk of adverse arrhythmic outcomes, including sudden cardiac death.

Phenotype and Clinical Outcomes in Desmin-Related Arrhythmogenic Cardiomyopathy.

BACKGROUND: Desmin (DES) pathogenic variants cause a small proportion of arrhythmogenic cardiomyopathy (ACM). Outcomes data on DES-related ACM are scarce. OBJECTIVES: This study sought to provide information on the clinical phenotype and outcomes of patients with ACM caused by pathogenic variants of the DES gene in a multicenter cohort. METHODS: We collected phenotypic and outcomes data from 16 families with DES-related ACM from 10 European centers. We assessed in vitro DES aggregates. Major cardiac events were compared to historical controls with lamin A/C truncating variant (LMNA-tv) and filament C truncating variant (FLNC-tv) ACM. RESULTS: Of 82 patients (54% males, median age: 36 years), 11 experienced sudden cardiac death (SCD) (n = 7) or heart failure death (HFd)/heart transplantation (HTx) (n = 4) before clinical evaluation. Among 68 survivors, 59 (86%) presented signs of cardiomyopathy, with left ventricular (LV) dominant (50%) or biventricular (34%) disease. Mean LV ejection fraction was 51% ± 13%; 36 of 53 had late gadolinium enhancement (ring-like pattern in 49%). During a median of 6.73 years (Q1-Q3: 3.55-9.52 years), the composite endpoint (sustained ventricular tachycardia, aborted SCD, implantable cardioverter-defibrillator therapy, SCD, HFd, and HTx) was achieved in 15 additional patients with HFd/HTx (n = 5) and SCD/aborted SCD/implantable cardioverter-defibrillator therapy/sustained ventricular tachycardia (n = 10). Male sex (P = 0.004), nonsustained ventricular tachycardia (P = 0.017) and LV ejection fraction ≤50% (P = 0.012) were associated with the composite endpoint. Males with DES variants had similar outcomes to historical FLNC-tv and LMNA-tv controls. However, females showed better outcomes than those with LMNA-tv. In vitro experiments showed the characteristic finding of DES aggregates in 7 of 12 variants. CONCLUSIONS: DES ACM is associated with poor outcomes which can be predicted with potentially successful treatments, underscoring the importance of familial evaluation and genetic studies to identify at risk individuals.

Incidence and risk factors for development of left ventricular hypertrophy in Fabry disease.

BACKGROUND: Left ventricular hypertrophy (LVH) is the principal cardiac manifestation of Fabry disease (FD). This study aimed to determine the incidence and predictors of LVH development in a contemporary cohort of patients with FD and no LVH at baseline evaluation. METHODS: Consecutively referred adult (aged ≥16 years) patients with FD were enrolled into an observational cohort study. Patients were prospectively followed in a specialist cardiomyopathy centre and the primary endpoint was the first detection of LVH (left ventricular mass index (LVMi) ≥115 g/m2 in men and ≥95 g/m2 in women). RESULTS: From a cohort of 393 patients, 214 (aged 35.8±13.8 years; 61 (29%) males) had no LVH at first evaluation. During a median follow-up of 9.4 years (IQR 4.7-12.7), 55 patients (24.6%) developed LVH. The estimated incidence of LVH was 11.3% (95% CI 6.5% to 16.1%) at 5 years, 29.1% (95% CI 21.5% to 36.7%) at 10 years and 45.0% (95% CI 33.8% to 62.4%) at 15 years of follow-up. On multivariable analysis, independent predictors for LVH development were age (HR 1.04 (95% CI 1.02 to 1.06) per 1-year increase, p<0.001), male sex (HR 2.90 (95% CI 1.66 to 5.09), p<0.001) and an abnormal ECG (HR 3.10 (95% CI 1.72 to 5.57), p<0.001). The annual rate of change in LVMi was +2.77 (IQR 1.45-4.62) g/m2/year in males and +1.38 (IQR 0.09-2.85) g/m2/year in females (p<0.001). CONCLUSIONS: Approximately one-quarter of patients with FD developed LVH during follow-up. Age, male sex and ECG abnormalities were associated with a higher risk of developing LVH in patients with FD.

Endomyocardial biopsy: safety and prognostic utility in paediatric and adult myocarditis in the European Society of Cardiology EURObservational Research Programme Cardiomyopathy and Myocarditis Long-Term Registry.

BACKGROUND AND AIMS: Contemporary multicentre data on clinical and diagnostic spectrum and outcome in myocarditis are limited. Study aims were to describe baseline features, 1-year follow-up, and baseline predictors of outcome in clinically suspected or biopsy-proven myocarditis (2013 European Society of Cardiology criteria) in adult and paediatric patients from the EURObservational Research Programme Cardiomyopathy and Myocarditis Long-Term Registry. METHODS: Five hundred eighty-one (68.0% male) patients, 493 adults, median age 38 (27-52) years, and 88 children, aged 8 (3-13) years, were divided into 3 groups: Group 1 (n = 233), clinically suspected myocarditis with abnormal cardiac magnetic resonance; Group 2 (n = 222), biopsy-proven myocarditis; and Group 3 (n = 126) clinically suspected myocarditis with normal or inconclusive or no cardiac magnetic resonance. Baseline features were analysed overall, in adults vs. children, and among groups. One-year outcome events included death/heart transplantation, ventricular assist device (VAD) or implantable cardioverter defibrillator (ICD) implantation, and hospitalization for cardiac causes. RESULTS: Endomyocardial biopsy, mainly right ventricular, had a similarly low complication rate in children and adults (4.7% vs. 4.9%, P = NS), with no procedure-related death. A classical myocarditis pattern on cardiac magnetic resonance was found in 31.3% of children and in 57.9% of adults with biopsy-proven myocarditis (P < .001). At 1-year follow-up, 11/410 patients (2.7%) died, 7 (1.7%) received a heart transplant, 3 underwent VAD (0.7%), and 16 (3.9%) underwent ICD implantation. Independent predictors at diagnosis of death or heart transplantation or hospitalization or VAD implantation or ICD implantation at 1-year follow-up were lower left ventricular ejection fraction and the need for immunosuppressants for new myocarditis diagnosis refractory to non-aetiology-driven therapy. CONCLUSIONS: Endomyocardial biopsy was safe, and cardiac magnetic resonance using Lake Louise criteria was less sensitive, particularly in children. Virus-negative lymphocytic myocarditis was predominant both in children and adults, and use of immunosuppressive treatments was low. Lower left ventricular ejection fraction and the need for immunosuppressants at diagnosis were independent predictors of unfavourable outcome events at 1 year.

Prevalence of Pathogenic Variants in Cardiomyopathy-Associated Genes in Acute Myocarditis: A Systematic Review and Meta-Analysis.

BACKGROUND: Acute myocarditis is an inflammatory condition that may precede the development of dilated or arrhythmogenic cardiomyopathy. OBJECTIVES: The aim of this study was to investigate the reported prevalence of pathogenic or likely pathogenic (P/LP) variants in cardiomyopathy-associated genes in patients with acute myocarditis. METHODS: For this systematic review and meta-analysis, the PubMed and Embase databases were searched on March 4, 2023. Observational studies evaluating the prevalence of P/LP variants in cardiomyopathy-associated genes in patients with acute myocarditis were included. Studies were stratified into adult and pediatric age groups and for the following scenarios: 1) complicated myocarditis (ie, presenting with acute heart failure, reduced left ventricular ejection fraction, or life-threatening ventricular arrhythmias); and 2) uncomplicated myocarditis. The study was registered with the International Prospective Register of Systematic Reviews (CRD42023408668) and followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. RESULTS: Of 732 studies identified, 8 met the inclusion criteria, providing data for 586 patients with acute myocarditis. A total of 89 P/LP variants in cardiomyopathy-associated genes were reported in 85 patients. For uncomplicated myocarditis, the pooled prevalence was 4.2% (95% CI: 1.8%-7.4%; I2 = 1.4%), whereas for complicated myocarditis, the pooled prevalence was 21.9% (95% CI: 14.3%-30.5%; I2 = 38.8%) and 44.5% (95% CI: 22.7%-67.4%; I2 = 52.8%) in adults and children, respectively. P/LP variants in desmosomal genes were predominant in uncomplicated myocarditis (64%), whereas sarcomeric gene variants were more prevalent in complicated myocarditis (58% in adults and 71% in children). CONCLUSIONS: Genetic variants are present in a large proportion of patients with acute myocarditis. The prevalence of genetic variants and the genes involved vary according to age and clinical presentation.

The Diagnostic and Therapeutic Implications of Phenocopies and Mimics of Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is a common myocardial disease defined by increased left ventricular wall thickness unexplained by loading conditions. HCM frequently is caused by pathogenic variants in sarcomeric protein genes, but several other syndromic, metabolic, infiltrative, and neuromuscular diseases can result in HCM phenocopies. This review summarizes the current understanding of these HCM mimics, highlighting their importance across the life course. The central role of a comprehensive, multiparametric diagnostic approach and the potential of precision medicine in tailoring treatment strategies are emphasized.

Prevalence of transthyretin cardiac amyloidosis in patients with high-degree AV block.

OBJECTIVE: Transthyretin amyloid cardiomyopathy (ATTR-CM) is an infiltrative cardiac disorder caused by deposition of wild type or mutated transthyretin. As ATTR-CM is associated with conduction disease, we sought to determine its prevalence in patients with idiopathic high-degree atrioventricular (AV) block requiring permanent pacemaker (PPM) implantation. METHODS: Consecutive patients aged 70-85 years undergoing PPM implantation for idiopathic high-degree AV block between November 2019 and November 2021 were offered a 3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) scan. Demographics, comorbidities, electrocardiographic and imaging data from the time of device implantation were retrospectively collected. RESULTS: 39 patients (79.5% male, mean (SD) age at device implantation 76.2 (2.9) years) had a DPD scan. 3/39 (7.7%, all male) had a result consistent with ATTR-CM (Perugini grade 2 or 3). Mean (SD) maximum wall thickness of those with a positive DPD scan was 19.0 mm (3.6 mm) vs 11.4 mm (2.7 mm) in those with a negative scan (p=0.06). All patients diagnosed with ATTR-CM had spinal canal stenosis and two had carpal tunnel syndrome. CONCLUSIONS: ATTR-CM should be considered in older patients requiring permanent pacing for high-degree AV block, particularly in the presence of left ventricular hypertrophy, carpal tunnel syndrome or spinal canal stenosis.

Cardiomyopathies in children and adolescents: aetiology, management, and outcomes in the European Society of Cardiology EURObservational Research Programme Cardiomyopathy and Myocarditis Registry.

BACKGROUND AND AIMS: Childhood-onset cardiomyopathies are rare and poorly characterized. This study examined the baseline characteristics and 1-year follow-up of children with cardiomyopathy in the first European Cardiomyopathy Registry. METHODS: Prospective data were collected on individuals aged 1-<18 years enrolled in the European Society of Cardiology EURObservational Research Programme Cardiomyopathy and Myocarditis long-term registry (June 2014-December 2016). RESULTS: A total of 633 individuals aged ≤18 years with hypertrophic [HCM; n = 388 (61.3%)], dilated [DCM; n = 206 (32.5%)], restrictive [RCM; n = 28 (4.4%)], and arrhythmogenic right ventricular cardiomyopathy [ARVC; n = 11 (1.7%)] were enrolled by 23 referral centres in 14 countries. Median age at diagnosis was 4.0 [interquartile range (IQR) 0-10] years, and there was a male predominance [n = 372 (58.8%)] across all subtypes, with the exception of DCM diagnosed <10 years of age; 621 (98.1%) patients were receiving cardiac medication and 80 (12.6%) had an implantable cardioverter-defibrillator. A total of 253 patients (253/535, 47.3%) had familial disease. Genetic testing was performed in 414 (67.8%) patients with a pathogenic or likely pathogenic variant reported in 250 (60.4%). Rare disease phenocopies were reported in 177 patients (28.0%) and were most frequent in patients under 10 years [142 (30.9%) vs. 35 (19.6%); P = .003]. Over a median follow-up of 12.5 months (IQR 11.3-15.3 months), 18 patients (3.3%) died [HCM n = 9 (2.6%), DCM n = 5 (3.0%), RCM n = 4 (16.0%)]. Heart failure events were most frequent in RCM patients (36.0%). CONCLUSIONS: The findings confirm the heterogeneous aetiology of childhood cardiomyopathies and show a high frequency of familial disease. Outcomes differed by cardiomyopathy subtype, highlighting a need for disease-specific evaluation and treatment.

Electrocardiographic abnormalities in patients with cardiomyopathies.

Abnormalities in impulse generation and transmission are among the first signs of cardiac remodeling in cardiomyopathies. Accordingly, 12-lead electrocardiogram (ECG) of patients with cardiomyopathies may show multiple abnormalities. Some findings are suggestive of specific disorders, such as the discrepancy between QRS voltages and left ventricular (LV) mass for cardiac amyloidosis or the inverted T waves in the right precordial leads for arrhythmogenic cardiomyopathy. Other findings are less sensitive and/or specific, but may orient toward a specific diagnosis in a patient with a specific phenotype, such as an increased LV wall thickness or a dilated LV. A "cardiomyopathy-oriented" mindset to ECG reading is important to detect the possible signs of an underlying cardiomyopathy and to interpret correctly the meaning of these alterations, which differs in patients with cardiomyopathies or other conditions.

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.

Management of arrhythmogenic right ventricular cardiomyopathy.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a disease characterised by fibrofatty replacement of the ventricular myocardium due to specific mutations, leading to ventricular arrhythmias and sudden cardiac death. Treating this condition can be challenging due to progressive fibrosis, phenotypic variations and small patient cohorts limiting the feasibility of conducting meaningful clinical trials. Although widely used, the evidence base for anti-arrhythmic drugs is limited. Beta-blockers are theoretically sound, yet their efficacy in reducing arrhythmic risk is not robust. Additionally, the impact of sotalol and amiodarone is inconsistent with studies reporting contradictory results. Emerging evidence suggests that combining flecainide and bisoprolol may be efficacious.Radiofrequency ablation has shown some potential in disrupting ventricular tachycardia circuits, with combined endo and epicardial ablation yielding better results which could be considered at the index procedure. In addition, stereotactic radiotherapy may be a future option that can decrease arrhythmias beyond simple scar formation by altering levels of Nav1.5 channels, Connexin 43 and Wnt signalling, potentially modifying myocardial fibrosis.Future therapies, such as adenoviruses and GSk3b modulation, are still in early-stage research. While implantable cardioverter-defibrillator implantation is a key intervention for reducing arrhythmic death, the risks of inappropriate shocks and device complications must be carefully considered.