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The phospholamban ( PLN ) pathogenic gene variant p.Arg14del causes cardiomyopathy, which is characterized by perinuclear PLN protein clustering and can lead to severe heart failure (HF). Elevated expression of dwarf open reading frame (DWORF), a protein counteracting the function of PLN in the sarcoplasmic reticulum (SR), can delay disease progression in a PLN-R14del mouse model. Here, we evaluated whether deletion of DWORF (DWORF -/- ) would have an opposite effect and accelerate age-dependent disease progression in wild-type (WT) mice and mice with a pathogenic PLN-R14del allele (R14 Δ/+ ). We show that DWORF -/- mice maintained a normal left ventricular ejection fraction (LVEF) during aging and no difference with WT control mice could be observed up to 20 mo of age. R14 Δ/+ mice maintained a normal cardiac function until 12 mo of age, but at 18 mo of age, LVEF was significantly reduced as compared with WT mice. Absence of DWORF did neither accelerate the R14 Δ/+ -induced reduction in LVEF nor enhance the increases in gene expression of markers related to cardiac remodeling and fibrosis and did not exacerbate cardiac fibrosis caused by the R14 Δ/+ mutation. Together, these results demonstrate that absence of DWORF does not accelerate or exacerbate PLN-R14del cardiomyopathy in mice harboring the pathogenic R14del allele. In addition, our data indicate that DWORF appears to be dispensable for cardiac function during aging. NEW & NOTEWORTHY Although DWORF overexpression significantly delayed heart failure development and strongly prolonged life span in PLN-R14del mice, the current study shows that deletion of DWORF does not accelerate or exacerbate PLN-R14del cardiomyopathy in mice harboring the pathogenic R14del allele. In addition, DWORF appears to be dispensable for cardiac function during aging. Changes in DWORF gene expression are therefore unlikely to contribute to the clinical heterogeneity observed in patients with PLN-R14del cardiomyopathy.

Aims: The heterozygous phospholamban (PLN) mutation R14del (PLN R14del +/- ) is associated with a severe arrhythmogenic cardiomyopathy (ACM) developing in the adult. "Superinhibition" of SERCA2a by PLN R14del is widely assumed to underlie the pathogenesis, but alternative mechanisms such abnormal energy metabolism have also been reported. This work aims to (1) to evaluate Ca 2+ dynamics and energy metabolism in a transgenic (TG) mouse model of the mutation prior to cardiomyopathy development; (2) to test whether they are causally connected., Methods: Ca 2+ dynamics, energy metabolism parameters, reporters of mitochondrial integrity, energy, and redox homeostasis were measured in ventricular myocytes of 8-12 weeks-old, phenotypically silent, TG mice. Mutation effects were compared to pharmacological PLN antagonism and analyzed during modulation of sarcoplasmic reticulum (SR) and cytosolic Ca 2+ compartments. Transcripts and proteins of relevant signaling pathways were evaluated., Results: The mutation was characterized by hyperdynamic Ca 2+ handling, compatible with a loss of SERCA2a inhibition by PLN. All components of energy metabolism were depressed; myocyte energy charge was preserved under quiescence but reduced during stimulation. Cytosolic Ca 2+ buffering or SERCA2a blockade reduced O 2 consumption with larger effect in the mutant. Signaling changes suggest cellular adaptation to perturbed Ca 2+ dynamics and response to stress., Conclusions: (1) PLN R14del +/- loses its ability to inhibit SERCA2a, which argues against SERCA2a superinhibition as a pathogenetic mechanism; (2) depressed energy metabolism, its enhanced dependency on Ca 2+ and activation of signaling responses point to an early involvement of metabolic stress in the pathogenesis of this ACM model., (© 2024 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.)

Background: MYH7 variants cause hypertrophic cardiomyopathy (HCM), noncompaction cardiomyopathy (NCCM), and dilated cardiomyopathy (DCM). Screening of relatives of patients with genetic cardiomyopathy is recommended from 10 to 12 years of age onward, irrespective of the affected gene., Objectives: This study sought to study the penetrance and prognosis of MYH7 variant-associated cardiomyopathies., Methods: In this multicenter cohort study, penetrance and major cardiomyopathy-related events (MCEs) were assessed in carriers of (likely) pathogenic MYH7 variants by using Kaplan-Meier curves and log-rank tests. Prognostic factors were evaluated using Cox regression with time-dependent coefficients., Results: In total, 581 subjects (30.1% index patients, 48.4% male, median age 37.0 years [IQR: 19.5-50.2 years]) were included. HCM was diagnosed in 226 subjects, NCCM in 70, and DCM in 55. Early penetrance and MCEs (age <12 years) were common among NCCM-associated variant carriers (21.2% and 12.0%, respectively) and DCM-associated variant carriers (15.3% and 10.0%, respectively), compared with HCM-associated variant carriers (2.9% and 2.1%, respectively). Penetrance was significantly increased in carriers of converter region variants (adjusted HR: 1.87; 95% CI: 1.15-3.04; P = 0.012) and at age ≤1 year in NCCM-associated or DCM-associated variant carriers (adjusted HR: 21.17; 95% CI: 4.81-93.20; P < 0.001) and subjects with a family history of early MCEs (adjusted HR: 2.45; 95% CI: 1.09-5.50; P = 0.030). The risk of MCE was increased in subjects with a family history of early MCEs (adjusted HR: 1.82; 95% CI: 1.15-2.87; P = 0.010) and at age ≤5 years in NCCM-associated or DCM-associated variant carriers (adjusted HR: 38.82; 95% CI: 5.16-291.88; P < 0.001)., Conclusions: MYH7 variants can cause cardiomyopathies and MCEs at a young age. Screening at younger ages may be warranted, particularly in carriers of NCCM- or DCM-associated variants and/or with a family history of MCEs at <12 years., Competing Interests: Funding Support and Author Disclosures This work was supported by the Netherlands Cardiovascular Research Initiative with the support of the Dutch Heart Foundation. Dr Jansen has received support from the Netherlands Cardiovascular Research Initiative with the support of the Dutch Heart Foundation (CVON2014-40 DOSIS, DCVA [Dutch Cardiovascular Alliance] 2020B005 DoubleDose) and from the Dutch Heart Foundation (Dekker 2015T041). Dr Christiaans has received support from the Netherlands Cardiovascular Research Initiative with the support of the Dutch Heart Foundation (CVON2015-12 e-Detect). Dr de Boer has received support from the Netherlands Cardiovascular Research Initiative with the support of the Dutch Heart Foundation (CVON2014-40 DOSIS, DCVA 2020B005 DoubleDose). Dr van Tintelen has received support from the Netherlands Cardiovascular Research Initiative with the support of the Dutch Heart Foundation (CVON2014-40 DOSIS, DCVA 2020B005 DoubleDose and CVON2015-12 e-Detect). Dr Asselbergs has received support from the Netherlands Cardiovascular Research Initiative with the support of the Dutch Heart Foundation (CVON2014-40 DOSIS, DCVA 2020B005 DoubleDose and CVON2015-12 e-Detect) and from the UCL Hospitals NIHR Biomedical Research Centre. Dr Baas has received support from the Netherlands Cardiovascular Research Initiative with the support of the Dutch Heart Foundation (CVON2014-40 DOSIS, DCVA 2020B005 DoubleDose and CVON2015-12 e-Detect) and from the Dutch Heart Foundation (Dekker 2015T041). All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: The p.Arg14del variant of the PLN (phospholamban) gene causes cardiomyopathy, leading to severe heart failure. Calcium handling defects and perinuclear PLN aggregation have both been suggested as pathological drivers of this disease. Dwarf open reading frame (DWORF) has been shown to counteract PLN regulatory calcium handling function in the sarco/endoplasmic reticulum (S/ER). Here, we investigated the potential disease-modulating action of DWORF in this cardiomyopathy and its effects on calcium handling and PLN aggregation., Methods: We studied a PLN-R14del mouse model, which develops cardiomyopathy with similar characteristics as human patients, and explored whether cardiac DWORF overexpression could delay cardiac deterioration. To this end, R14 Δ/Δ (homozygous PLN-R14del) mice carrying the DWORF transgene (R14 Δ/Δ DWORF Tg [R14 Δ/Δ mice carrying the DWORF transgene]) were used., Results: DWORF expression was suppressed in hearts of R14 Δ/Δ mice with severe heart failure. Restoration of DWORF expression in R14 Δ/Δ mice delayed cardiac fibrosis and heart failure and increased life span >2-fold (from 8 to 18 weeks). DWORF accelerated sarcoplasmic reticulum calcium reuptake and relaxation in isolated cardiomyocytes with wild-type PLN, but in R14 Δ/Δ cardiomyocytes, sarcoplasmic reticulum calcium reuptake and relaxation were already enhanced, and no differences were detected between R14 Δ/Δ and R14 Δ/Δ DWORF Tg . Rather, DWORF overexpression delayed the appearance and formation of large pathogenic perinuclear PLN clusters. Careful examination revealed colocalization of sarcoplasmic reticulum markers with these PLN clusters in both R14 Δ/Δ mice and human p.Arg14del PLN heart tissue, and hence these previously termed aggregates are comprised of abnormal organized S/ER. This abnormal S/ER organization in PLN-R14del cardiomyopathy contributes to cardiomyocyte cell loss and replacement fibrosis, consequently resulting in cardiac dysfunction., Conclusions: Disorganized S/ER is a major characteristic of PLN-R14del cardiomyopathy in humans and mice and results in cardiomyocyte death. DWORF overexpression delayed PLN-R14del cardiomyopathy progression and extended life span in R14 Δ/Δ mice, by reducing abnormal S/ER clusters., Competing Interests: Disclosures The UMCG, which employs several of the authors, has received research grants and fees from AstraZeneca, Abbott, Boehringer Ingelheim, Cardior Pharmaceuticals GmbH, Ionis Pharmaceuticals, Inc, Novo Nordisk, and Roche. R.A. de Boer received speaker fees from Abbott, AstraZeneca, Bayer, Novartis, and Roche. The other authors report no conflicts.

Cardiomyopathies are a significant contributor to cardiovascular morbidity and mortality, mainly due to the development of heart failure and increased risk of sudden cardiac death (SCD). Despite improvement in survival with contemporary treatment, SCD remains an important cause of mortality in cardiomyopathies. It occurs at a rate ranging between 0.15% and 0.7% per year (depending on the cardiomyopathy), which significantly surpasses SCD incidence in the age- and sex-matched general population. The risk of SCD is affected by multiple factors including the aetiology, genetic basis, age, sex, physical exertion, the extent of myocardial disease severity, conduction system abnormalities, and electrical instability, as measured by various metrics. Over the past decades, the knowledge on the mechanisms and risk factors for SCD has substantially improved, allowing for a better-informed risk stratification. However, unresolved issues still challenge the guidance of SCD prevention in patients with cardiomyopathies. In this review, we aim to provide an in-depth discussion of the contemporary concepts pertinent to understanding the burden, risk assessment and prevention of SCD in cardiomyopathies (dilated, non-dilated left ventricular, hypertrophic, arrhythmogenic right ventricular, and restrictive). The review first focuses on SCD incidence in cardiomyopathies and then summarizes established and emerging risk factors for life-threatening arrhythmias/SCD. Finally, it discusses validated approaches to the risk assessment and evidence-based measures for SCD prevention in cardiomyopathies, pointing to the gaps in evidence and areas of uncertainties that merit future clarification., (© 2023 European Society of Cardiology.)

The c.40&#95;42delAGA variant in the phospholamban gene (PLN) has been associated with dilated and arrhythmogenic cardiomyopathy, with up to 70% of carriers experiencing a major cardiac event by age 70. However, there are carriers who remain asymptomatic at older ages. To understand the mechanisms behind this incomplete penetrance, we evaluated potential phenotypic and genetic modifiers in 74 PLN:c.40&#95;42delAGA carriers identified in 36,339 participants of the Lifelines population cohort. Asymptomatic carriers (N = 48) showed shorter QRS duration (- 5.73 ms, q value = 0.001) compared to asymptomatic non-carriers, an effect we could replicate in two different independent cohorts. Furthermore, symptomatic carriers showed a higher correlation (r Pearson  = 0.17) between polygenic predisposition to higher QRS (PGS QRS ) and QRS (p value = 1.98 × 10 -8 ), suggesting that the effect of the genetic variation on cardiac rhythm might be increased in symptomatic carriers. Our results allow for improved clinical interpretation for asymptomatic carriers, while our approach could guide future studies on genetic diseases with incomplete penetrance., (© 2023. The Author(s).)

Cardiomyopathies represent significant contributors to cardiovascular morbidity and mortality. Over the past decades, a progress has occurred in characterization of the genetic background and major pathophysiological mechanisms, which has been incorporated into a more nuanced diagnostic approach and risk stratification. Furthermore, medications targeting core disease processes and/or their downstream adverse effects have been introduced for several cardiomyopathies. Combined with standard care and prevention of sudden cardiac death, these novel and emerging targeted therapies offer a possibility of improving the outcomes in several cardiomyopathies. Therefore, the aim of this document is to summarize practical approaches to the treatment of cardiomyopathies, which includes the evidence-based novel therapeutic concepts and established principles of care, tailored to the individual patient aetiology and clinical presentation of the cardiomyopathy. The scope of the document encompasses contemporary treatment of dilated, hypertrophic, restrictive and arrhythmogenic cardiomyopathy. It was based on an expert consensus reached at the Heart Failure Association online Workshop, held on 18 March 2021., (© 2023 European Society of Cardiology.)

Importance: Dapagliflozin has been shown to improve overall health status based on aggregate summary scores of the Kansas City Cardiomyopathy Questionnaire (KCCQ) in patients with heart failure (HF) with mildly reduced or preserved ejection fraction enrolled in the Dapagliflozin Evaluation to Improve the Lives of Patients With Preserved Ejection Fraction Heart Failure (DELIVER) trial. A comprehensive understanding of the responsiveness of individual KCCQ items would allow clinicians to better inform patients on expected changes in daily living with treatment., Objective: To examine the association of dapagliflozin treatment with changes in individual components of the KCCQ., Design, Setting, and Participants: This is a post hoc exploratory analysis of DELIVER, a randomized double-blind placebo-controlled trial conducted at 353 centers in 20 countries from August 2018 to March 2022. KCCQ was administered at randomization and 1, 4, and 8 months. Scores of individual KCCQ components were scaled from 0 to 100. Eligibility criteria included symptomatic HF with left ventricular ejection fraction greater than 40%, elevated natriuretic peptide levels, and evidence of structural heart disease. Data were analyzed from November 2022 to February 2023., Main Outcomes and Measures: Changes in the 23 individual KCCQ components at 8 months., Interventions: Dapagliflozin, 10 mg, once daily or placebo., Results: Baseline KCCQ data were available for 5795 of 6263 randomized patients (92.5%) (mean [SD] age, 71.5 [9.5] years; 3344 male [57.7%] and 2451 female [42.3%]). Dapagliflozin was associated with larger improvements in almost all KCCQ components at 8 months compared with placebo. The most significant improvements with dapagliflozin were observed in frequency of lower limb edema (difference, 3.2; 95% CI, 1.6-4.8; P < .001), sleep limitation by shortness of breath (difference, 3.0; 95% CI, 1.6-4.4; P < .001), and limitation in desired activities by shortness of breath (difference, 2.8; 95% CI, 1.3-4.3; P < .001). Similar treatment patterns were observed in longitudinal analyses integrating data from months 1, 4, and 8. Higher proportions of patients treated with dapagliflozin experienced improvements, and fewer had deteriorations across most individual components., Conclusions and Relevance: In this study of patients with HF with mildly reduced or preserved ejection fraction, dapagliflozin was associated with improvement in a broad range of individual KCCQ components, with the greatest benefits in domains related to symptom frequency and physical limitations. Potential improvements in specific symptoms and activities of daily living might be more readily recognizable and easily communicated to patients., Trial Registration: ClinicalTrials.gov Identifier: NCT03619213.

The transforming growth factor-β (TGF-β) superfamily member, myostatin, is a negative regulator of muscle growth and may contribute to adverse cardiac remodeling. Whether suppressing myostatin could benefit pressure-overloaded heart remains unclear. We investigated the effects of pharmacological inhibition of myostatin on cardiac fibrosis and hypertrophy in a mouse model of pressure overload induced by transverse aortic constriction (TAC). Two weeks after the surgery, TAC and sham mice were randomly divided into groups receiving mRK35, a monoclonal anti-myostatin antibody, or vehicle (PBS) for 8 wk. Significant progressive cardiac hypertrophy was observed in TAC mice, as reflected by the increased wall thickness, ventricular weight, and cross-sectional area of cardiomyocytes. In the groups treated with mRK35, compared with sham mice, cardiac fibrosis was increased in TAC mice, accompanied with elevated mRNA expression of fibrotic genes. However, among the TAC mice, mRK35 did not reduce cardiac hypertrophy or fibrosis. Body weight, lean mass, and wet weights of tibialis anterior and gastrocnemius muscle bundle were increased by mRK35. When compared with the TAC-PBS group, the TAC mice treated with mRK35 demonstrated greater forelimb grip strength and a larger mean size of gastrocnemius fibers. Our data suggest that mRK35 does not attenuate cardiac hypertrophy and fibrosis in a TAC mouse model but has positive effects on muscle mass and muscle strength. Anti-myostatin treatment may have therapeutic value against muscle wasting in cardiac vascular disease. NEW & NOTEWORTHY Recent research has highlighted the importance of inhibiting TGF-β signaling in mitigating cardiac dysfunction and remodeling. As myostatin belongs to the TGF-β family, we evaluated the impact of myostatin inhibition using mRK35 in TAC-operated mice. Our data demonstrate that mRK35 significantly increased body weight, muscle mass, and muscle strength but did not attenuate cardiac hypertrophy or fibrosis. Pharmacological inhibition of myostatin may provide therapeutic benefits for the management of muscle wasting in cardiovascular diseases.

Aims: Ongoing adverse remodeling is a hallmark of heart failure (HF), which might be reflected by either focal or diffuse myocardial fibrosis. Therefore, in (pre)clinical settings, we used immunohistochemistry or cardiac magnetic resonance imaging (CMR) to investigate the association of (focal or diffuse) fibrosis with cardiac biomarkers and adverse events in HF., Methods and Results: In C57Bl/6J mice, we determined the presence and extent of myocardial fibrosis 6 weeks post-myocardial infarction (MI). Furthermore, we studied 159 outpatient HF patients who underwent CMR, and determined focal and diffuse fibrosis by late gadolinium enhancement (LGE) and post-contrast T1 time of the non-LGE myocardium, respectively. HF patients were categorized based on the presence of LGE, and by the median post-contrast T1 time. Kaplan-Meier and Cox regression analyses were used to determine the association of fibrosis with HF hospitalization and all-cause mortality. LGE was detected in 61 (38%) patients. Cardiac biomarker levels were comparable between LGE-positive and LGE-negative patients. LGE-positive patients with a short T1 time had elevated levels of both NT-proBNP and galectin-3 (1611 vs. 453 ng/L, p = 0.026 and 20 vs. 15 μg/L, p = 0.004, respectively). This was not observed in LGE-negative patients. Furthermore, a short T1 time in LGE-positive patients was associated with a higher risk of adverse events (log-rank p = 0.01)., Conclusion: This study implies that cardiac biomarkers reflect active remodeling of the non-infarcted myocardium of patients with focal myocardial scarring. Diffuse fibrosis, in contrast to focal scarring, might have a higher prognostic value regarding adverse outcomes in HF patients.

Background: Sodium-glucose cotransporter-2 inhibitors have emerged as a key pharmacotherapy in heart failure (HF) with both reduced and preserved ejection fraction. The benefit of other HF therapies may be modified by sex, but whether sex modifies the treatment effect and safety profile of sodium-glucose cotransporter-2 inhibitors remains unclear. Our analyses aim to assess the effect of sex on the efficacy and safety of dapagliflozin., Methods: In a prespecified patient-level pooled analysis of DAPA-HF (Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure) and DELIVER (Dapagliflozin Evaluation to Improve the Lives of Patients With Preserved Ejection Fraction Heart Failure), clinical outcomes were compared by sex (including the composite of cardiovascular death or worsening HF events, cardiovascular death, all-cause death, total events [first and recurrent HF hospitalization and cardiovascular death], and Kansas City Cardiomyopathy Questionnaire scores) across the spectrum of left ventricular ejection fraction., Results: Of a total of 11 007 randomized patients, 3856 (35%) were women. Women with HF were older and had higher body mass index but were less likely to have a history of diabetes and myocardial infarction or stroke and more likely to have hypertension and atrial fibrillation compared with men. At baseline, women had higher ejection fraction but worse Kansas City Cardiomyopathy Questionnaire scores than men did. After adjustment for baseline differences, women were less likely than men to experience cardiovascular death (adjusted hazard ratio, 0.69 [95% CI, 0.60-0.79]), all-cause death (adjusted hazard ratio, 0.69 [95% CI, 0.62-0.78]), HF hospitalizations (adjusted hazard ratio, 0.82 [95% CI, 0.72-0.94]), and total events (adjusted rate ratio, 0.77 [95% CI, 0.71-0.84]). Dapagliflozin reduced the primary end point in both men and women similarly ( P interaction =0.77) with no sex-related differences in secondary outcomes (all P interaction >0.35) or safety events. The benefit of dapagliflozin was observed across the entire ejection fraction spectrum and was not modified by sex ( P interaction >0.40). There were no sex-related differences in serious adverse events, adverse events, or drug discontinuation attributable to adverse events., Conclusions: In DAPA-HF and DELIVER, the response to dapagliflozin was similar between men and women. Sex did not modify the treatment effect of dapagliflozin across the range of ejection fraction.

Competing Interests: Conflict of interest: R.A.d.B. has received research grants and/or fees from AstraZeneca, Abbott, Boehringer Ingelheim, Cardior Pharmaceuticals GmbH, Ionis Pharmaceuticals, Inc., Novo Nordisk, and Roche; and has had speaker engagements with Abbott, AstraZeneca, Bayer, Bristol Myers Squibb, Novartis, and Roche. J.B. has received honoraria for lectures/consulting from Amgen, AstraZeneca, Bayer, BMS, Boehringer Ingelheim, Cardior, Corvia, CVRx, Novartis, Pfizer, Vifor and research support for the department from Zoll, CVRx, and Abiomed.

Aims: Phospholamban (PLN) p.Arg14del mutation carriers are at risk of developing malignant ventricular arrhythmias (VAs) and/or heart failure. Currently, left ventricular ejection fraction (LVEF) plays an important role in risk assessment for VA in these individuals. We aimed to study the incremental prognostic value of left ventricular mechanical dispersion (LVMD) by echocardiographic deformation imaging for prediction of sustained VA in PLN p.Arg14del mutation carriers., Methods and Results: We included 243 PLN p.Arg14del mutation carriers, which were classified into three groups according to the '45/45' rule: (i) normal left ventricular (LV) function, defined as preserved LVEF ≥45% with normal LVMD ≤45 ms (n = 139), (ii) mechanical LV dysfunction, defined as preserved LVEF ≥45% with abnormal LVMD &gt;45 ms (n = 63), and (iii) overt LV dysfunction, defined as reduced LVEF &lt;45% (n = 41). During a median follow-up of 3.3 (interquartile range 1.8-6.0) years, sustained VA occurred in 35 individuals. The negative predictive value of having normal LV function at baseline was 99% [95% confidence interval (CI): 92-100%] for developing sustained VA. The positive predictive value of mechanical LV dysfunction was 20% (95% CI: 15-27%). Mechanical LV dysfunction was an independent predictor of sustained VA in multivariable analysis [hazard ratio adjusted for VA history: 20.48 (95% CI: 2.57-162.84)]., Conclusion: LVMD has incremental prognostic value on top of LVEF in PLN p.Arg14del mutation carriers, particularly in those with preserved LVEF. The '45/45' rule is a practical approach to echocardiographic risk stratification in this challenging group of patients. This approach may also have added value in other diseases where LVEF deterioration is a relative late marker of myocardial dysfunction., Competing Interests: Conflict of interest: The University Medical Center Groningen, which employs several of the authors, has received research grants and/or fees from AstraZeneca, Abbott, Bristol-Myers Squibb, Novartis, Novo Nordisk, and Roche. R.A.d.B. received speaker fees from Abbott, AstraZeneca, Novartis, and Roche., (© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: A pathogenic variant in the gene encoding phospholamban (PLN), a protein that regulates calcium homeostasis of cardiomyocytes, causes PLN cardiomyopathy. It is characterized by a high arrhythmic burden and can progress to severe cardiomyopathy. Risk assessment guides implantable cardioverter-defibrillator therapy and benefits from personalization. Whether sex-specific differences in PLN cardiomyopathy exist is unknown., Objective: The purpose of this study was to improve the accuracy of PLN cardiomyopathy diagnosis and risk assessment by investigating sex-specific aspects., Methods: We analyzed a multicenter cohort of 933 patients (412 male, 521 female) with the PLN p.(Arg14del) pathogenic variant following up on a recently developed PLN risk model. Sex-specific differences in the incidence of risk model components were investigated: low-voltage electrocardiogram (ECG), premature ventricular contractions, negative T waves, and left ventricular ejection fraction., Results: Sustained ventricular arrhythmias (VAs) occurred in 77 males (18.7%) and 61 females (11.7%) (P = .004). Of the 933 cohort members, 287 (31%) had ≥1 low-voltage ECG during follow-up (180 females [63%], 107 males [37%]; P = .006). Female sex, age, age at clinical presentation, and proband status predicted low-voltage ECG during follow-up (area under the curve: 0.78). Sustained VA-free survival was lowest in males with low-voltage ECG (P <.001)., Conclusion: Low-voltage ECGs predict sustained VA and are a component of the PLN risk model. Low-voltage ECGs are more common in females, yet prognostic value is greater in males. Future studies should determine the impact of this difference on the risk prediction of PLN cardiomyopathy and possibly other cardiomyopathies., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Genetic cardiomyopathies are disorders of the cardiac muscle, most often explained by pathogenic mutations in genes encoding sarcomere, cytoskeleton, or ion channel proteins. Clinical phenotypes such as heart failure and arrhythmia are classically treated with generic drugs, but aetiology-specific and targeted treatments are lacking. As a result, cardiomyopathies still present a major burden to society, and affect many young and older patients. The Translational Committee of the Heart Failure Association (HFA) and the Working Group of Myocardial Function of the European Society of Cardiology (ESC) organized a workshop to discuss recent advances in molecular and physiological studies of various forms of cardiomyopathies. The study of cardiomyopathies has intensified after several new study setups became available, such as induced pluripotent stem cells, three-dimensional printing of cells, use of scaffolds and engineered heart tissue, with convincing human validation studies. Furthermore, our knowledge on the consequences of mutated proteins has deepened, with relevance for cellular homeostasis, protein quality control and toxicity, often specific to particular cardiomyopathies, with precise effects explaining the aberrations. This has opened up new avenues to treat cardiomyopathies, using contemporary techniques from the molecular toolbox, such as gene editing and repair using CRISPR-Cas9 techniques, antisense therapies, novel designer drugs, and RNA therapies. In this article, we discuss the connection between biology and diverse clinical presentation, as well as promising new medications and therapeutic avenues, which may be instrumental to come to precision medicine of genetic cardiomyopathies., (© 2021 The Authors. European Journal of Heart Failure published by John Wiley & Sons Ltd on behalf of European Society of Cardiology.)

Inherited cardiomyopathy caused by the p.(Arg14del) pathogenic variant of the phospholamban ( PLN ) gene is characterized by intracardiomyocyte PLN aggregation and can lead to severe dilated cardiomyopathy. We recently reported that pre-emptive depletion of PLN attenuated heart failure (HF) in several cardiomyopathy models. Here, we investigated if administration of a Pln -targeting antisense oligonucleotide (ASO) could halt or reverse disease progression in mice with advanced PLN-R14del cardiomyopathy. To this aim, homozygous PLN-R14del (PLN-R14 Δ/Δ ) mice received PLN-ASO injections starting at 5 or 6 weeks of age, in the presence of moderate or severe HF, respectively. Mice were monitored for another 4 months with echocardiographic analyses at several timepoints, after which cardiac tissues were examined for pathological remodeling. We found that vehicle-treated PLN-R14 Δ/Δ mice continued to develop severe HF, and reached a humane endpoint at 8.1 ± 0.5 weeks of age. Both early and late PLN-ASO administration halted further cardiac remodeling and dysfunction shortly after treatment start, resulting in a life span extension to at least 22 weeks of age. Earlier treatment initiation halted disease development sooner, resulting in better heart function and less remodeling at the study endpoint. PLN-ASO treatment almost completely eliminated PLN aggregates, and normalized levels of autophagic proteins. In conclusion, these findings indicate that PLN-ASO therapy may have beneficial outcomes in PLN-R14del cardiomyopathy when administered after disease onset. Although existing tissue damage was not reversed, further cardiomyopathy progression was stopped, and PLN aggregates were resolved.

In the year 2021, the universal definition and classification of heart failure (HF) was published that defines HF as a clinical syndrome with symptoms and/or signs caused by a cardiac abnormality and corroborated by elevated natriuretic peptide levels or objective evidence of cardiogenic congestion. This definition and the classification of HF with reduced ejection fraction (HFrEF), mildly reduced, and HF with preserved ejection fraction (HFpEF) is consistent with the 2021 ESC Guidelines on HF. Among several other new recommendations, these guidelines give a Class I indication for the use of the sodium-glucose co-transporter 2 (SGLT2) inhibitors dapagliflozin and empagliflozin in HFrEF patients. As the first evidence-based treatment for HFpEF, in the EMPEROR-Preserved trial, empagliflozin reduced the composite endpoint of cardiovascular death and HF hospitalizations. Several reports in 2021 have provided novel and detailed analyses of device and medical therapy in HF, especially regarding sacubitril/valsartan, SGLT2 inhibitors, mineralocorticoid receptor antagonists, ferric carboxymaltose, soluble guanylate cyclase activators, and cardiac myosin activators. In patients hospitalized with COVID-19, acute HF and myocardial injury is quite frequent, whereas myocarditis and long-term damage to the heart are rather uncommon., (© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: The p.(Arg14del) pathogenic variant (R14del) of the PLN (phospholamban) gene is a prevalent cause of cardiomyopathy with heart failure. The exact underlying pathophysiology is unknown, and a suitable therapy is unavailable. We aim to identify molecular perturbations underlying this cardiomyopathy in a clinically relevant PLN-R14del mouse model., Methods: We investigated the progression of cardiomyopathy in PLN-R14 Δ/Δ mice using echocardiography, ECG, and histological tissue analysis. RNA sequencing and mass spectrometry were performed on cardiac tissues at 3 (before the onset of disease), 5 (mild cardiomyopathy), and 8 (end stage) weeks of age. Data were compared with cardiac expression levels of mice that underwent myocardial ischemia-reperfusion or myocardial infarction surgery, in an effort to identify alterations that are specific to PLN-R14del-related cardiomyopathy., Results: At 3 weeks of age, PLN-R14 Δ/Δ mice had normal cardiac function, but from the age of 4 weeks, we observed increased myocardial fibrosis and impaired global longitudinal strain. From 5 weeks onward, ventricular dilatation, decreased contractility, and diminished ECG voltages were observed. PLN protein aggregation was present before onset of functional deficits. Transcriptomics and proteomics revealed differential regulation of processes involved in remodeling, inflammation, and metabolic dysfunction, in part, similar to ischemic heart disease. Altered protein homeostasis pathways were identified exclusively in PLN-R14 Δ/Δ mice, even before disease onset, in concert with aggregate formation., Conclusions: We mapped the development of PLN-R14del-related cardiomyopathy and identified alterations in proteostasis and PLN protein aggregation among the first manifestations of this disease, which could possibly be a novel target for therapy.

Heart failure (HF) is a major cause of morbidity and mortality worldwide, highlighting an urgent need for novel treatment options, despite recent improvements. Aberrant Ca 2+ handling is a key feature of HF pathophysiology. Restoring the Ca 2+ regulating machinery is an attractive therapeutic strategy supported by genetic and pharmacological proof of concept studies. Here, we study antisense oligonucleotides (ASOs) as a therapeutic modality, interfering with the PLN/SERCA2a interaction by targeting Pln mRNA for downregulation in the heart of murine HF models. Mice harboring the PLN R14del pathogenic variant recapitulate the human dilated cardiomyopathy (DCM) phenotype; subcutaneous administration of PLN-ASO prevents PLN protein aggregation, cardiac dysfunction, and leads to a 3-fold increase in survival rate. In another genetic DCM mouse model, unrelated to PLN (Cspr3/Mlp -/- ), PLN-ASO also reverses the HF phenotype. Finally, in rats with myocardial infarction, PLN-ASO treatment prevents progression of left ventricular dilatation and improves left ventricular contractility. Thus, our data establish that antisense inhibition of PLN is an effective strategy in preclinical models of genetic cardiomyopathy as well as ischemia driven HF., (© 2021. The Author(s).)

This position paper focusses on the pathophysiology, diagnosis and management of women diagnosed with a cardiomyopathy, or at risk of heart failure (HF), who are planning to conceive or present with (de novo or previously unknown) HF during or after pregnancy. This includes the heterogeneous group of heart muscle diseases such as hypertrophic, dilated, arrhythmogenic right ventricular and non-classified cardiomyopathies, left ventricular non-compaction, peripartum cardiomyopathy, Takotsubo syndrome, adult congenital heart disease with HF, and patients with right HF. Also, patients with a history of chemo-/radiotherapy for cancer or haematological malignancies need specific pre-, during and post-pregnancy assessment and counselling. We summarize the current knowledge about pathophysiological mechanisms, including gene mutations, clinical presentation, diagnosis, and medical and device management, as well as risk stratification. Women with a known diagnosis of a cardiomyopathy will often require continuation of drug therapy, which has the potential to exert negative effects on the foetus. This position paper assists in balancing benefits and detrimental effects., (© 2021 The Authors. European Journal of Heart Failure published by John Wiley & Sons Ltd on behalf of European Society of Cardiology.)

For patients with hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM) or arrhythmogenic cardiomyopathy (ACM), screening for pathogenic variants has become standard clinical practice. Genetic cascade screening also allows the identification of relatives that carry the same mutation as the proband, but disease onset and severity in mutation carriers often remains uncertain. Early detection of disease onset may allow timely treatment before irreversible changes are present. Although plasma biomarkers may aid in the prediction of disease onset, monitoring relies predominantly on identifying early clinical symptoms, on imaging techniques like echocardiography (Echo) and cardiac magnetic resonance imaging (CMR), and on (ambulatory) electrocardiography (electrocardiograms (ECGs)). In contrast to most other cardiac diseases, which are explained by a combination of risk factors and comorbidities, genetic cardiomyopathies have a clear primary genetically defined cardiac background. Cardiomyopathy cohorts could therefore have excellent value in biomarker studies and in distinguishing biomarkers related to the primary cardiac disease from those related to extracardiac, secondary organ dysfunction. Despite this advantage, biomarker investigations in cardiomyopathies are still limited, most likely due to the limited number of carriers in the past. Here, we discuss not only the potential use of established plasma biomarkers, including natriuretic peptides and troponins, but also the use of novel biomarkers, such as cardiac autoantibodies in genetic cardiomyopathy, and discuss how we can gauge biomarker studies in cardiomyopathy cohorts for heart failure at large.

Myocardial fibrosis is the excessive deposition of extracellular matrix proteins, including collagens, in the heart. In cardiomyopathies, the formation of interstitial fibrosis and/or replacement fibrosis is almost always part of the pathological cardiac remodeling process. Different forms of cardiomyopathies show particular patterns of myocardial fibrosis that can be considered as distinctive hallmarks. Although formation of fibrosis is initially aimed to be a reparative mechanism, in the long term, on-going and excessive myocardial fibrosis may lead to arrhythmias and stiffening of the heart wall and subsequently to diastolic dysfunction. Ultimately, adverse remodeling with progressive myocardial fibrosis can lead to heart failure. Not surprisingly, the presence of fibrosis in cardiomyopathies, even when subtle, has consistently been associated with complications and adverse outcomes. In the last decade, non-invasive in vivo techniques for visualization of myocardial fibrosis have emerged, and have been increasingly used in research and in the clinic. In this review, we will describe the epidemiology, distribution, and role of myocardial fibrosis in genetic cardiomyopathies, including hypertrophic, dilated, arrhythmogenic, and non-compaction cardiomyopathy, and a few specific forms of genetic cardiomyopathies., (Copyright © 2019. Published by Elsevier Inc.)

Phospholamban (PLN) plays a role in cardiomyocyte calcium handling as primary inhibitor of sarco/endoplasmic reticulum Ca 2+ -ATPase (SERCA). The p.(Arg14del) pathogenic variant in the PLN gene results in a high risk of developing dilated or arrhythmogenic cardiomyopathy with heart failure. There is no established treatment other than standard heart failure therapy or heart transplantation. In this study, we generated a novel mouse model with the PLN-R14del pathogenic variant, performed detailed phenotyping, and tested the efficacy of established heart failure therapies eplerenone or metoprolol. Heterozygous PLN-R14del mice demonstrated increased susceptibility to ex vivo induced arrhythmias, and cardiomyopathy at 18 months of age, which was not accelerated by isoproterenol infusion. Homozygous PLN-R14del mice exhibited an accelerated phenotype including cardiac dilatation, contractile dysfunction, decreased ECG potentials, high susceptibility to ex vivo induced arrhythmias, myocardial fibrosis, PLN protein aggregation, and early mortality. Neither eplerenone nor metoprolol administration improved cardiac function or survival. In conclusion, our novel PLN-R14del mouse model exhibits most features of human disease. Administration of standard heart failure therapy did not rescue the phenotype, underscoring the need for better understanding of the pathophysiology of PLN-R14del-associated cardiomyopathy. This model provides a great opportunity to study the pathophysiology, and to screen for potential therapeutic treatments.

Peripartum cardiomyopathy (PPCM) is a potentially life-threatening condition typically presenting as heart failure with reduced ejection fraction (HFrEF) in the last month of pregnancy or in the months following delivery in women without another known cause of heart failure. This updated position statement summarizes the knowledge about pathophysiological mechanisms, risk factors, clinical presentation, diagnosis and management of PPCM. As shortness of breath, fatigue and leg oedema are common in the peripartum period, a high index of suspicion is required to not miss the diagnosis. Measurement of natriuretic peptides, electrocardiography and echocardiography are recommended to promptly diagnose or exclude heart failure/PPCM. Important differential diagnoses include pulmonary embolism, myocardial infarction, hypertensive heart disease during pregnancy, and pre-existing heart disease. A genetic contribution is present in up to 20% of PPCM, in particular titin truncating variant. PPCM is associated with high morbidity and mortality, but also with a high probability of partial and often full recovery. Use of guideline-directed pharmacological therapy for HFrEF is recommended in all patients respecting contraindications during pregnancy/lactation. The oxidative stress-mediated cleavage of the hormone prolactin into a cardiotoxic fragment has been identified as a driver of PPCM pathophysiology. Pharmacological blockade of prolactin release using bromocriptine as a disease-specific therapy in addition to standard therapy for heart failure treatment has shown promising results in two clinical trials. Thresholds for devices (implantable cardioverter-defibrillators, cardiac resynchronization therapy and implanted long-term ventricular assist devices) are higher in PPCM than in other conditions because of the high rate of recovery. The important role of education and counselling around contraception and future pregnancies is emphasised., (© 2019 The Authors. European Journal of Heart Failure © 2019 European Society of Cardiology.)

Aims: The p.Arg14del founder mutation in the gene encoding phospholamban (PLN) is associated with an increased risk of malignant ventricular arrhythmia (VA) and heart failure. It has been shown to lead to calcium overload, cardiomyocyte damage, and eventually to myocardial fibrosis. This study sought to investigate ventricular function, the extent and localization of myocardial fibrosis and the associations with ECG features and VA in PLN p.Arg14del mutation carriers., Methods and Results: Cardiovascular magnetic resonance (CMR) data of 150 mutation carriers were analysed retrospectively. Left ventricular (LV) and right ventricular (RV) volumes, mass, and ejection fraction were measured. The extent of late gadolinium enhancement (LGE) was expressed as a percentage of myocardial mass. All standard ECG parameters were measured. Occurrence of VA was analysed on ambulatory 24-h and/or exercise electrocardiography, if available. Mean age was 40 ± 15 years, 42% males, and 7% were index patients while 93% were pre-symptomatic carriers identified after family cascade screening. Mean LV ejection fraction (LVEF) and RV ejection fraction were 58 ± 9% and 55 ± 9%, respectively. LV-LGE was present in 91% of mutation carriers with reduced LVEF (<45%) and in 30% of carriers with preserved LVEF. In carriers with positive LV-LGE, its median extent was 5.9% (interquartile range 3.2-12.7). LGE was mainly observed in the inferolateral wall. Carriers with inverted T-waves in the lateral ECG leads more often had LV-LGE (P < 0.01) than carriers without. Finally, the presence of LV-LGE, but not attenuated R-waves and inverted lateral T-waves, was independently associated with VA., Conclusion: LV myocardial fibrosis is present in many PLN p.Arg14del mutation carriers, and who still have a preserved LVEF. It is seen predominantly in the LV inferolateral wall and corresponds with electrocardiographic repolarization abnormalities. Although preliminary, myocardial fibrosis was found to be independently associated with VA. Our findings support the use of CMR with LGE early in the diagnostic work-up.

Aims: The non-desmosomal phospholamban PLN p.Arg14del mutation was identified in patients diagnosed with dilated cardiomyopathy (DCM) and/or arrhythmogenic cardiomyopathy (ACM). We aimed to investigate whether this mutation leads to aggregation, aggresome formation and autophagy of mutant PLN protein., Methods and Results: We studied 20 complete heart specimens of PLN p.Arg14del mutation carriers [mean age 48 ± 15 years; 55% males], either from autopsies or from explants. Gross and microscopic examination showed biventricular cardiomyopathy with histopathological features of both ACM and DCM, i.e. a combination of fibrofatty replacement and interstitial fibrosis. Immunohistochemistry for PLN showed large perinuclear PLN protein aggregates in cardiomyocytes in both ventricles in all examined hearts. The median numbers of PLN-containing aggregates were 12 per 5 mm(2) range 3-48 mm2 in right ventricular myocardium and 13 per 5 mm(2) (range 5-89 mm(2) ) in left ventricular myocardium. Double immunohistochemical staining showed colocalization of autophagy markers p62 (sequestosome-1) and microtubule-associated protein light chain 3 with PLN in all aggregates, suggestive of degradation by selective autophagy. On electron microscopy, the ultrastructural appearance of these PLN-containing aggregates was typical of aggresomes; they were not surrounded by a membrane, and were located adjacent to the microtubular organizing centre. PLN-containing aggregates were not found in 10 PLN-negative cases of idiopathic and genetic DCM or in seven cases of desmosomal ACM., Conclusions: PLN p.Arg14del cardiomyopathy is a biventricular cardiomyopathy characterized by large perinuclear PLN protein aggregates with a typical ultrastructural appearance of aggresomes. PLN detected by immunohistochemistry appears to be a sensitive and specific marker for this disease., (© 2016 John Wiley & Sons Ltd.)

As heart failure with preserved ejection fraction (HFpEF) rises to epidemic proportions, major steps in patient management and therapeutic development are badly needed. With the current position paper we seek to update our view on HFpEF as a highly complex systemic syndrome, from risk factors and mechanisms to long-term clinical manifestations. We will revise recent advances in animal model development, experimental set-ups and basic and translational science approaches to HFpEF research, highlighting their drawbacks and advantages. Directions are provided for proper model selection as well as for integrative functional evaluation from the in vivo setting to in vitro cell function testing. Additionally, we address new research challenges that require integration of higher-order inter-organ and inter-cell communication to achieve a full systems biology perspective of HFpEF. [ABSTRACT FROM AUTHOR]

Aims To investigate whether phospholamban gene (PLN) mutations underlie patients diagnosed with either arrhythmogenic right ventricular cardiomyopathy (ARVC) or idiopathic dilated cardiomyopathy (DCM). Methods and results We screened a cohort of 97 ARVC and 257 DCM unrelated index patients for PLN mutations and evaluated their clinical characteristics. PLN mutation R14del was identified in 12 (12 % ) ARVC patients and in 39 (15 % ) DCM patients. Haplotype analysis revealed a common founder, estimated to be between 575 and 825 years old. A low voltage electrocardiogram was present in 46 % of R14del carriers. Compared with R14del– DCM patients, R14del+ DCM patients more often demonstrated appropriate implantable cardioverter defibrillator discharge (47 % vs. 10 % , P < 0.001), cardiac transplantation (18 % vs. 2 % , P < 0.001), and a family history for sudden cardiac death (SCD) at < 50 years (36 % vs. 16 % , P = 0.007). We observed a similar pattern in the ARVC patients although this was not statistically significant. The average age of 26 family members who died of SCD was 37.7 years. Immunohistochemistry in available myocardial samples revealed absent/depressed plakoglobin levels at intercalated disks in five of seven (71 % ) R14del+ ARVC samples, but in only one of nine (11 % ) R14del+ DCM samples (P = 0.03). Conclusions The PLN R14del founder mutation is present in a substantial number of patients clinically diagnosed with DCM or ARVC. R14del+ patients diagnosed with DCM showed an arrhythmogenic phenotype, and SCD at young age can be the presenting symptom. These findings support the concept of ‘arrhythmogenic cardiomyopathy’. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

The article offers information on the clinical utility gene for arrhythmogenic right ventricular cardiomyopathy (ARVC). It mentions that ARVC is an inheritable disease categorized by functional and structural abnormalities of the right ventricle (RV), with or without concomitant disease in left ventricle (LV). It states that the diagnosis is created when a patient accomplishes the altered criteria which encompasses regional and/or global structural and dysfunction alterations.

Background: Frailty is increasing in prevalence. Because patients with frailty are often perceived to have a less favorable risk/benefit profile, they may be less likely to receive new pharmacologic treatments. We investigated the efficacy and tolerability of dapagliflozin according to frailty status in patients with heart failure with mildly reduced or preserved ejection fraction randomized in DELIVER (Dapagliflozin Evaluation to Improve the Lives of Patients With Preserved Ejection Fraction Heart Failure).Methods: Frailty was measured using the Rockwood cumulative deficit approach. The primary end point was time to a first worsening heart failure event or cardiovascular death.Results: Of the 6263 patients randomized, a frailty index (FI) was calculable in 6258. In total, 2354 (37.6%) patients had class 1 frailty (FI ≤0.210; ie, not frail), 2413 (38.6%) had class 2 frailty (FI 0.211-0.310; ie, more frail), and 1491 (23.8%) had class 3 frailty (FI ≥0.311; ie, most frail). Greater frailty was associated with a higher rate of the primary end point (per 100 person-years): FI class 1, 6.3 (95% CI 5.7-7.1); class 2, 8.3 (7.5-9.1); and class 3, 13.4 (12.1-14.7; P<0.001). The effect of dapagliflozin (as a hazard ratio) on the primary end point from FI class 1 to 3 was 0.85 (95% CI, 0.68-1.06), 0.89 (0.74-1.08), and 0.74 (0.61-0.91), respectively (Pinteraction=0.40). Although patients with a greater degree of frailty had worse Kansas City Cardiomyopathy Questionnaire scores at baseline, their improvement with dapagliflozin was greater than it was in patients with less frailty: placebo-corrected improvement in Kansas City Cardiomyopathy Questionnaire Overall Summary Score at 4 months in FI class 1 was 0.3 (95% CI, -0.9 to 1.4); in class 2, 1.5 (0.3-2.7); and in class 3, 3.4 (1.7-5.1; Pinteraction=0.021). Adverse reactions and treatment discontinuation, although more frequent in patients with a greater degree of frailty, were not more common with dapagliflozin than with placebo irrespective of frailty class.Conclusions: In DELIVER, frailty was common and associated with worse outcomes. The benefit of dapagliflozin was consistent across the range of frailty studied. The improvement in health-related quality of life with dapagliflozin occurred early and was greater in patients with a higher level of frailty.Registration: URL: https://www.Clinicaltrials: gov; Unique identifier: NCT03619213. [ABSTRACT FROM AUTHOR]

Phospholamban (PLN) p.Arg14del cardiomyopathy is characterized by a distinct arrhythmogenic biventricular phenotype that can be predominantly left ventricular, right ventricular, or both. Our aim was to further elucidate distinct features of this cardiomyopathy with respect to the distribution of desmosomal proteins observed by immunofluorescence (IF) in comparison to desmosomal arrhythmogenic cardiomyopathy and co-existent genetic variants. We studied eight explanted heart specimens from PLN p.Arg14del mutation carriers. Macro- and microscopic examination revealed biventricular presence of fibrofatty replacement and interstitial fibrosis. Five out of 8 (63%) patients met consensus criteria for both arrhythmogenic right ventricular cardiomyopathy (ARVC) and dilated cardiomyopathy (DCM). In four cases, targeted next-generation sequencing revealed one additional pathogenic variant and six variants of unknown significance. IF showed diminished junction plakoglobin signal intensity at the intercalated disks in 4 (67%) out of 6 cases fulfilling ARVC criteria but normal intensity in both cases fulfilling only DCM criteria. Notably, the four cases with diminished junction plakoglobin were also those where an additional gene variant was detected. IF for two proteins recently investigated in desmosomal arrhythmogenic cardiomyopathy (ACM), synapse-associated protein 97 and glycogen synthase kinase-3 beta, showed a distinct distributional pattern in comparison to desmosomal ACM. In 7 (88%) out of 8 cases we observed both a strong synapse-associated protein 97 signal at the sarcomeres and no glycogen synthase kinase-3 beta translocation to the intercalated discs. Phospholamban p.Arg14del cardiomyopathy is characterized by a distinct molecular signature compared to desmosomal ACM, specifically a different desmosomal protein distribution. This study substantiates the idea that additional genetic variants play a role in the phenotypical heterogeneity. • Phospholamban (PLN) p.Arg14del cardiomyopathy is a biventricular arrhythmogenic cardiomyopathy (ACM). • It has a distinct molecular signature in comparison to desmosomal ACM. • Histopathologically, it is characterized by biventricular fibrofatty replacement and interstitial fibrosis. • Additional genetic variants play a role in the observed phenotypical heterogeneity. [ABSTRACT FROM AUTHOR]