Publications by authors named "William J McKenna"

226 Publications

Preventing Sudden Death in Arrhythmogenic Cardiomyopathy: Careful family and genetic evaluation key to appropriate diagnosis and management.

Can J Cardiol 2020 Dec 21. Epub 2020 Dec 21.

University College London - Institute of Cardiovascular Science, London, United Kingdom. Electronic address:

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http://dx.doi.org/10.1016/j.cjca.2020.12.013DOI Listing
December 2020

Epidemiology of the inherited cardiomyopathies.

Nat Rev Cardiol 2021 Jan 7;18(1):22-36. Epub 2020 Sep 7.

Section of Advanced HF & Transplant Cardiology, Medical University of South Carolina, Charleston, SC, USA.

In the absence of contemporary, population-based epidemiological studies, estimates of the incidence and prevalence of the inherited cardiomyopathies have been derived from screening studies, most often of young adult populations, to assess cardiovascular risk or to detect the presence of disease in athletes or military recruits. The global estimates for hypertrophic cardiomyopathy (1/500 individuals), dilated cardiomyopathy (1/250) and arrhythmogenic right ventricular cardiomyopathy (1/5,000) are probably conservative given that only individuals who fulfil diagnostic criteria would have been included. This caveat is highly relevant because a substantial minority or even a majority of individuals who carry disease-causing genetic variants and are at risk of disease complications have incomplete and/or late-onset disease expression. The genetic literature on cardiomyopathy, which is often focused on the identification of genetic variants, has been biased in favour of pedigrees with higher penetrance. In clinical practice, an abnormal electrocardiogram with normal or non-diagnostic imaging results is a common finding for the sarcomere variants that cause hypertrophic cardiomyopathy, the titin and sarcomere variants that cause dilated cardiomyopathy and the desmosomal variants that cause either arrhythmogenic right ventricular cardiomyopathy or dilated cardiomyopathy. Therefore, defining the genetic epidemiology is also challenging given the overlapping phenotypes, incomplete and age-related expression, and highly variable penetrance even within individual families carrying the same genetic variant.
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http://dx.doi.org/10.1038/s41569-020-0428-2DOI Listing
January 2021

Diagnosis of arrhythmogenic cardiomyopathy: The Padua criteria.

Int J Cardiol 2020 11 16;319:106-114. Epub 2020 Jun 16.

Department of Cardiac, Thoracic and Vascular Sciences and Public Health, University of Padova, Italy.

The original designation of "Arrhythmogenic right ventricular (dysplasia/) cardiomyopathy"(ARVC) was used by the scientists who first discovered the disease, in the pre-genetic and pre-cardiac magnetic resonance era, to describe a new heart muscle disease predominantly affecting the right ventricle, whose cardinal clinical manifestation was the occurrence of malignant ventricular arrhythmias. Subsequently, autopsy investigations, genotype-phenotype correlations studies and the increasing use of contrast-enhancement cardiac magnetic resonance showed that the fibro-fatty replacement of the myocardium represents the distinctive phenotypic feature of the disease that affects the myocardium of both ventricles, with left ventricular involvement which may parallel or exceed the severity of right ventricular involvement. This has led to the new designation of "Arrhythmogenic Cardiomyopathy" (ACM), that represents the evolution of the original term of ARVC. The present International Expert Consensus document proposes an upgrade of the criteria for diagnosis of the entire spectrum of the phenotypic variants of ACM. The proposed "Padua criteria" derive from the diagnostic approach to ACM, which has been developed over 30 years by the multidisciplinary team of basic researchers and clinical cardiologists of the Medical School of the University of Padua. The Padua criteria are a working framework to improve the diagnosis of ACM by introducing new diagnostic criteria regarding tissue characterization findings by contrast-enhanced cardiac magnetic resonance, depolarization/repolarization ECG abnormalities and ventricular arrhythmia features for diagnosis of the left ventricular phenotype. The proposed diagnostic criteria need to be further validated by future clinical studies in large cohorts of patients.
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http://dx.doi.org/10.1016/j.ijcard.2020.06.005DOI Listing
November 2020

Arrhythmogenic Right Ventricular Cardiomyopathy: Characterization of Left Ventricular Phenotype and Differential Diagnosis With Dilated Cardiomyopathy.

J Am Heart Assoc 2020 03 2;9(5):e014628. Epub 2020 Mar 2.

Department of Cardio-Thoraco-Vascular Sciences and Public Health University of Padua Italy.

Background This study assessed the prevalence of left ventricular (LV) involvement and characterized the clinical, electrocardiographic, and imaging features of LV phenotype in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Differential diagnosis between ARVC-LV phenotype and dilated cardiomyopathy (DCM) was evaluated. Methods and Results The study population included 87 ARVC patients (median age 34 years) and 153 DCM patients (median age 51 years). All underwent cardiac magnetic resonance with quantitative tissue characterization. Fifty-eight ARVC patients (67%) had LV involvement, with both LV systolic dysfunction and LV late gadolinium enhancement (LGE) in 41/58 (71%) and LV-LGE in isolation in 17 (29%). Compared with DCM, the ARVC-LV phenotype was statistically significantly more often characterized by low QRS voltages in limb leads, T-wave inversion in the inferolateral leads and major ventricular arrhythmias. LV-LGE was found in all ARVC patients with LV systolic dysfunction and in 69/153 (45%) of DCM patients. Patients with ARVC and LV systolic dysfunction had a greater amount of LV-LGE (25% versus 13% of LV mass; <0.01), mostly localized in the subepicardial LV wall layers. An LV-LGE ≥20% had a 100% specificity for diagnosis of ARVC-LV phenotype. An inverse correlation between LV ejection fraction and LV-LGE extent was found in the ARVC-LV phenotype (=-0.63; <0.01), but not in DCM (=-0.01; =0.94). Conclusions LV involvement in ARVC is common and characterized by clinical and cardiac magnetic resonance features which differ from those seen in DCM. The most distinctive feature of ARVC-LV phenotype is the large amount of LV-LGE/fibrosis, which impacts directly and negatively on the LV systolic function.
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http://dx.doi.org/10.1161/JAHA.119.014628DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7335583PMC
March 2020

Biventricular pacemaker therapy improves exercise capacity in patients with non-obstructive hypertrophic cardiomyopathy via augmented diastolic filling on exercise.

Eur J Heart Fail 2020 07 23;22(7):1263-1272. Epub 2020 Jan 23.

Norwich Medical School, University of East Anglia, Norwich, UK.

Aims: Treatment options for patients with non-obstructive hypertrophic cardiomyopathy (HCM) are limited. We sought to determine whether biventricular (BiV) pacing improves exercise capacity in HCM patients, and whether this is via augmented diastolic filling.

Methods And Results: Thirty-one patients with symptomatic non-obstructive HCM were enrolled. Following device implantation, patients underwent detailed assessment of exercise diastolic filling using radionuclide ventriculography in BiV and sham pacing modes. Patients then entered an 8-month crossover study of BiV and sham pacing in random order, to assess the effect on exercise capacity [peak oxygen consumption (VO )]. Patients were grouped on pre-specified analysis according to whether left ventricular end-diastolic volume increased (+LVEDV) or was unchanged/decreased (-LVEDV) with exercise at baseline. Twenty-nine patients (20 male, mean age 55 years) completed the study. There were 14 +LVEDV patients and 15 -LVEDV patients. Baseline peak VO was lower in -LVEDV patients vs. +LVEDV patients (16.2 ± 0.9 vs. 19.9 ± 1.1 mL/kg/min, P = 0.04). BiV pacing significantly increased exercise ΔLVEDV (P = 0.004) and Δstroke volume (P = 0.008) in -LVEDV patients, but not in +LVEDV patients. Left ventricular ejection fraction and end-systolic elastance did not increase with BiV pacing in either group. This translated into significantly greater improvements in exercise capacity (peak VO  + 1.4 mL/kg/min, P = 0.03) and quality of life scores (P = 0.02) in -LVEDV patients during the crossover study. There was no effect on left ventricular mechanical dyssynchrony in either group.

Conclusion: Symptomatic patients with non-obstructive HCM may benefit from BiV pacing via augmentation of diastolic filling on exercise rather than contractile improvement. This may be due to relief of diastolic ventricular interaction.

Clinical Trial Registration: ClinicalTrials.gov NCT00504647.
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http://dx.doi.org/10.1002/ejhf.1722DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7540697PMC
July 2020

RNA sequencing-based transcriptome profiling of cardiac tissue implicates novel putative disease mechanisms in FLNC-associated arrhythmogenic cardiomyopathy.

Int J Cardiol 2020 03 6;302:124-130. Epub 2019 Dec 6.

Centre for Heart Muscle Disease, Institute of Cardiovascular Science, University College London, London, UK. Electronic address:

Arrhythmogenic cardiomyopathy (ACM) encompasses a group of inherited cardiomyopathies including arrhythmogenic right ventricular cardiomyopathy (ARVC) whose molecular disease mechanism is associated with dysregulation of the canonical WNT signalling pathway. Recent evidence indicates that ARVC and ACM caused by pathogenic variants in the FLNC gene encoding filamin C, a major cardiac structural protein, may have different molecular mechanisms of pathogenesis. We sought to identify dysregulated biological pathways in FLNC-associated ACM. RNA was extracted from seven paraffin-embedded left ventricular tissue samples from deceased ACM patients carrying FLNC variants and sequenced. Transcript levels of 623 genes were upregulated and 486 genes were reduced in ACM in comparison to control samples. The cell adhesion pathway and ILK signalling were among the prominent dysregulated pathways in ACM. Consistent with these findings, transcript levels of cell adhesion genes JAM2, NEO1, VCAM1 and PTPRC were upregulated in ACM samples. Moreover, several actin-associated genes, including FLNC, VCL, PARVB and MYL7, were suppressed, suggesting dysregulation of the actin cytoskeleton. Analysis of the transcriptome for dysregulated biological pathways predicted activation of inflammation and apoptosis and suppression of oxidative phosphorylation and MTORC1 signalling in ACM. Our data suggests dysregulated cell adhesion and ILK signalling as novel putative pathogenic mechanisms of ACM caused by FLNC variants which are distinct from the postulated disease mechanism of classic ARVC caused by desmosomal gene mutations. This knowledge could help in the design of future gene therapy strategies which would target specific components of these pathways and potentially lead to novel treatments for ACM.
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http://dx.doi.org/10.1016/j.ijcard.2019.12.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6940594PMC
March 2020

2019 HRS expert consensus statement on evaluation, risk stratification, and management of arrhythmogenic cardiomyopathy: Executive summary.

Heart Rhythm 2019 11;16(11):e373-e407

University of Rochester Medical Center, Rochester, New York.

Arrhythmogenic cardiomyopathy (ACM) is an arrhythmogenic disorder of the myocardium not secondary to ischemic, hypertensive, or valvular heart disease. ACM incorporates a broad spectrum of genetic, systemic, infectious, and inflammatory disorders. This designation includes, but is not limited to, arrhythmogenic right/left ventricular cardiomyopathy, cardiac amyloidosis, sarcoidosis, Chagas disease, and left ventricular noncompaction. The ACM phenotype overlaps with other cardiomyopathies, particularly dilated cardiomyopathy with arrhythmia presentation that may be associated with ventricular dilatation and/or impaired systolic function. This expert consensus statement provides the clinician with guidance on evaluation and management of ACM and includes clinically relevant information on genetics and disease mechanisms. PICO questions were utilized to evaluate contemporary evidence and provide clinical guidance related to exercise in arrhythmogenic right ventricular cardiomyopathy. Recommendations were developed and approved by an expert writing group, after a systematic literature search with evidence tables, and discussion of their own clinical experience, to present the current knowledge in the field. Each recommendation is presented using the Class of Recommendation and Level of Evidence system formulated by the American College of Cardiology and the American Heart Association and is accompanied by references and explanatory text to provide essential context. The ongoing recognition of the genetic basis of ACM provides the opportunity to examine the diverse triggers and potential common pathway for the development of disease and arrhythmia.
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http://dx.doi.org/10.1016/j.hrthm.2019.09.019DOI Listing
November 2019

Novel strategies to evaluate the effectiveness of heart failure services.

Rev Esp Cardiol (Engl Ed) 2020 03 24;73(3):200-204. Epub 2019 Oct 24.

Heart Hospital, Hamad Medical Corporation, Doha, Qatar.

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http://dx.doi.org/10.1016/j.rec.2019.09.009DOI Listing
March 2020

Filamin C variants are associated with a distinctive clinical and immunohistochemical arrhythmogenic cardiomyopathy phenotype.

Int J Cardiol 2020 05 8;307:101-108. Epub 2019 Oct 8.

Centre for Heart Muscle Disease, Institute of Cardiovascular Science, University College London, London, UK.

Background: Pathogenic variants in the filamin C (FLNC) gene are associated with inherited cardiomyopathies including dilated cardiomyopathy with an arrhythmogenic phenotype. We evaluated FLNC variants in arrhythmogenic cardiomyopathy (ACM) and investigated the disease mechanism at a molecular level.

Methods: 120 gene-elusive ACM patients who fulfilled diagnostic criteria for arrhythmogenic right ventricular cardiomyopathy (ARVC) were screened by whole exome sequencing. Fixed cardiac tissue from FLNC variant carriers who had died suddenly was investigated by histology and immunohistochemistry.

Results: Novel or rare FLNC variants, four null and five variants of unknown significance, were identified in nine ACM probands (7.5%). In FLNC null variant carriers (including family members, n = 16) Task Force diagnostic electrocardiogram repolarization/depolarization abnormalities were uncommon (19%), echocardiography was normal in 69%, while 56% had >500 ventricular ectopics/24 h or ventricular tachycardia on Holter and 67% had late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMRI). Ten gene positive individuals (63%) had abnormalities on ECG or CMRI that are not included in the current diagnostic criteria for ARVC. Immunohistochemistry showed altered key protein distribution, distinctive from that observed in ARVC, predominantly in the left ventricle.

Conclusions: ACM associated with FLNC variants presents with a distinctive phenotype characterized by Holter arrhythmia and LGE on CMRI with unremarkable ECG and echocardiographic findings. Clinical presentation in asymptomatic mutation carriers at risk of sudden death may include abnormalities which are currently non-diagnostic for ARVC. At the molecular level, the pathogenic mechanism related to FLNC appears different to classic forms of ARVC caused by desmosomal mutations.
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http://dx.doi.org/10.1016/j.ijcard.2019.09.048DOI Listing
May 2020

Genetic Risk of Arrhythmic Phenotypes in Patients With Dilated Cardiomyopathy.

J Am Coll Cardiol 2019 09;74(11):1480-1490

Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado. Electronic address:

Background: Genotype-phenotype correlations in dilated cardiomyopathy (DCM) and, in particular, the effects of gene variants on clinical outcomes remain poorly understood.

Objectives: The purpose of this study was to investigate the prognostic role of genetic variant carrier status in a large cohort of DCM patients.

Methods: A total of 487 DCM patients were analyzed by next-generation sequencing and categorized the disease genes into functional gene groups. The following composite outcome measures were assessed: 1) all-cause mortality; 2) heart failure-related death, heart transplantation, or destination left ventricular assist device implantation (DHF/HTx/VAD); and 3) sudden cardiac death/sustained ventricular tachycardia/ventricular fibrillation (SCD/VT/VF).

Results: A total of 183 pathogenic/likely pathogenic variants were found in 178 patients (37%): 54 (11%) Titin; 19 (4%) Lamin A/C (LMNA); 24 (5%) structural cytoskeleton-Z disk genes; 16 (3.5%) desmosomal genes; 46 (9.5%) sarcomeric genes; 8 (1.6%) ion channel genes; and 11 (2.5%) other genes. All-cause mortality was no different between variant carriers and noncarriers (p = 0.99). A trend toward worse SCD/VT/VF (p = 0.062) and DHF/HTx/VAD (p = 0.061) was found in carriers. Carriers of desmosomal and LMNA variants experienced the highest rate of SCD/VT/VF, which was independent of the left ventricular ejection fraction.

Conclusions: Desmosomal and LMNA gene variants identify the subset of DCM patients who are at greatest risk for SCD and life-threatening ventricular arrhythmias, regardless of the left ventricular ejection fraction.
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http://dx.doi.org/10.1016/j.jacc.2019.06.072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6750731PMC
September 2019

Myoarchitectural disarray of hypertrophic cardiomyopathy begins pre-birth.

J Anat 2019 11 26;235(5):962-976. Epub 2019 Jul 26.

Institute of Cardiovascular Science, University College London, London, UK.

Myoarchitectural disarray - the multiscalar disorganisation of myocytes, is a recognised histopathological hallmark of adult human hypertrophic cardiomyopathy (HCM). It occurs before the establishment of left ventricular hypertrophy (LVH) but its early origins and evolution around the time of birth are unknown. Our aim is to investigate whether myoarchitectural abnormalities in HCM are present in the fetal heart. We used wild-type, heterozygous and homozygous hearts (n = 56) from a Mybpc3-targeted knock-out HCM mouse model and imaged the 3D micro-structure by high-resolution episcopic microscopy. We developed a novel structure tensor approach to extract, display and quantify myocyte orientation and its local angular uniformity by helical angle, angle of intrusion and myoarchitectural disarray index, respectively, immediately before and after birth. In wild-type, we demonstrate uniformity of orientation of cardiomyocytes with smooth transitions of helical angle transmurally both before and after birth but with traces of disarray at the septal insertion points of the right ventricle. In comparison, heterozygous mice free of LVH, and homozygous mice showed not only loss of the normal linear helical angulation transmural profiles observed in wild-type but also fewer circumferentially arranged myocytes at birth. Heterozygous and homozygous showed more disarray with a wider distribution than in wild-type before birth. In heterozygous mice, disarray was seen in the anterior, septal and inferior walls irrespective of stage, whereas in homozygous mice it extended to the whole LV circumference including the lateral wall. In conclusion, myoarchitectural disarray is detectable in the fetal heart of an HCM mouse model before the development of LVH.
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http://dx.doi.org/10.1111/joa.13058DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6794206PMC
November 2019

Definition and treatment of arrhythmogenic cardiomyopathy: an updated expert panel report.

Eur J Heart Fail 2019 08 18;21(8):955-964. Epub 2019 Jun 18.

Department of Clinical Genetics, Amsterdam Cardiovascular Sciences, University Medical Center, University of Amsterdam, Amsterdam, The Netherlands.

It is 35 years since the first description of arrhythmogenic right ventricular cardiomyopathy (ARVC) and more than 20 years since the first reports establishing desmosomal gene mutations as a major cause of the disease. Early advances in the understanding of the clinical, pathological and genetic architecture of ARVC resulted in consensus diagnostic criteria, which proved to be sensitive but not entirely specific for the disease. In more recent years, clinical and genetic data from families and the recognition of a much broader spectrum of structural disorders affecting both ventricles and associated with a propensity to ventricular arrhythmia have raised many questions about pathogenesis, disease terminology and clinical management. In this paper, we present the conclusions of an expert round table that aimed to summarise the current state of the art in arrhythmogenic cardiomyopathies and to define future research priorities.
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http://dx.doi.org/10.1002/ejhf.1534DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6685753PMC
August 2019

Understanding the Myocardial Architecture of Hypertrophic Cardiomyopathy for Clinical Care.

J Am Coll Cardiol 2019 05;73(20):2503-2505

Heart Hospital, Hamad Medical Corporation, Doha, Qatar.

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http://dx.doi.org/10.1016/j.jacc.2019.03.466DOI Listing
May 2019

Risk score for the exclusion of arrhythmic events in arrhythmogenic right ventricular cardiomyopathy at first presentation.

Int J Cardiol 2019 09 1;290:100-105. Epub 2019 May 1.

Cardiomyopathy Service, Royal Brompton Hospital, London, UK.

Aims: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetically determined heart muscle disorder associated with an increased risk of life-threatening arrhythmias in some patients. Risk stratification remains challenging. Therefore, we sought a non-invasive, easily applicable risk score to predict sustained ventricular arrhythmias in these patients.

Methods: Cohort of Patients who fulfilled the 2010 ARVC task force criteria were consecutively recruited. Detailed clinical data were collected at baseline and during follow up. The clinical endpoint was a composite of recurrent sustained ventricular arrhythmias and hospitalization due to ventricular arrhythmias. Multivariable logistic regression was used to develop models to predict the arrhythmic risk. A cohort including patients from other registries in UK, Canada and Switzerland was used as a validation population.

Results: One hundred and thirty-five patients were included of whom 35 patients (31.9%) reached the endpoint. A model consisting of filtered QRS duration on signal-averaged ECG, non-sustained VT (NSVT) on 24 h-ECG, and absence of negative T waves in lead aVR on 12‑lead surface ECG was able to predict arrhythmic events with a sensitivity of 81.8%, specificity of 84.0% and a negative predictive value of 95.5% at the first presentation of the disease. This risk score was validated in international ARVC registry patients.

Conclusion: A risk score consisting of a filtered QRS duration ≥117 ms, presence of NSVT on 24 h-ECG and absence of negative T waves in lead aVR was able to predict arrhythmic events at first presentation of the disease.
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http://dx.doi.org/10.1016/j.ijcard.2019.04.090DOI Listing
September 2019

2019 HRS expert consensus statement on evaluation, risk stratification, and management of arrhythmogenic cardiomyopathy.

Heart Rhythm 2019 11 9;16(11):e301-e372. Epub 2019 May 9.

University of Rochester Medical Center, Rochester, New York.

Arrhythmogenic cardiomyopathy (ACM) is an arrhythmogenic disorder of the myocardium not secondary to ischemic, hypertensive, or valvular heart disease. ACM incorporates a broad spectrum of genetic, systemic, infectious, and inflammatory disorders. This designation includes, but is not limited to, arrhythmogenic right/left ventricular cardiomyopathy, cardiac amyloidosis, sarcoidosis, Chagas disease, and left ventricular noncompaction. The ACM phenotype overlaps with other cardiomyopathies, particularly dilated cardiomyopathy with arrhythmia presentation that may be associated with ventricular dilatation and/or impaired systolic function. This expert consensus statement provides the clinician with guidance on evaluation and management of ACM and includes clinically relevant information on genetics and disease mechanisms. PICO questions were utilized to evaluate contemporary evidence and provide clinical guidance related to exercise in arrhythmogenic right ventricular cardiomyopathy. Recommendations were developed and approved by an expert writing group, after a systematic literature search with evidence tables, and discussion of their own clinical experience, to present the current knowledge in the field. Each recommendation is presented using the Class of Recommendation and Level of Evidence system formulated by the American College of Cardiology and the American Heart Association and is accompanied by references and explanatory text to provide essential context. The ongoing recognition of the genetic basis of ACM provides the opportunity to examine the diverse triggers and potential common pathway for the development of disease and arrhythmia.
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http://dx.doi.org/10.1016/j.hrthm.2019.05.007DOI Listing
November 2019

Prediction of ventricular arrhythmia and sudden death in arrhythmogenic right ventricular cardiomyopathy.

Eur Heart J 2019 06;40(23):1859-1861

Section of Cardiovascular Diseases, Yale School of Medicine and YNHH Heart and Vascular Center, New Haven, CT, USA.

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http://dx.doi.org/10.1093/eurheartj/ehz195DOI Listing
June 2019

Heart failure in patients with arrhythmogenic right ventricular cardiomyopathy: Genetic characteristics.

Int J Cardiol 2019 07 27;286:99-103. Epub 2019 Jan 27.

Cardiomyopathy Service, Royal Brompton Hospital, London, United Kingdom.

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetically determined heart muscle disorder. The incidence of heart failure (HF) in ARVC has been reported at 5-13%. We aimed to define the genotype and disease progression of ARVC patients with HF.

Methods: Patients with a definite diagnosis of ARVC who underwent genetic testing were consecutively recruited. Detailed clinical data was collected at baseline and during follow up. Clinical endpoint was a composite of heart transplantation and death due to HF.

Results: 135 patients were included. 8 (5.9%) patients reached the endpoint. Patients reaching the endpoint were significantly more likely to carry a Plakophilin 2 mutation than patients without HF, and 50% had multiple variants, however only one patient had 2 pathogenic mutations.

Conclusions: HF is a rare but significant outcome of patients with a definite diagnosis of ARVC. Patients with HF predominantly carried Plakophilin 2 mutations and often had multiple variants. RV dysfunction appears to be a determinant of heart transplantation and death.
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http://dx.doi.org/10.1016/j.ijcard.2019.01.065DOI Listing
July 2019

Effect of Trimetazidine Dihydrochloride Therapy on Exercise Capacity in Patients With Nonobstructive Hypertrophic Cardiomyopathy: A Randomized Clinical Trial.

JAMA Cardiol 2019 03;4(3):230-235

University College London Institute of Cardiovascular Science, London, United Kingdom.

Importance: Hypertrophic cardiomyopathy causes limiting symptoms in patients, mediated partly through inefficient myocardial energy use. There is conflicting evidence for therapy with inhibitors of myocardial fatty acid metabolism in patients with nonobstructive hypertrophic cardiomyopathy.

Objective: To determine the effect of oral therapy with trimetazidine, a direct inhibitor of fatty acid β-oxidation, on exercise capacity in patients with symptomatic nonobstructive hypertrophic cardiomyopathy.

Design, Setting, And Participants: This randomized, placebo-controlled, double-blind clinical trial at The Heart Hospital, University College London Hospitals, London, United Kingdom was performed between May 31, 2012, and September 8, 2014. The trial included 51 drug-refractory symptomatic (New York Heart Association class ≥2) patients aged 24 to 74 years with a maximum left ventricular outflow tract gradient 50 mm Hg or lower and a peak oxygen consumption during exercise of 80% or less predicted value for age and sex. Statistical analysis was performed from March 1, 2016 through July 4, 2018.

Interventions: Participants were randomly assigned to trimetazidine, 20 mg, 3 times daily (n = 27) or placebo (n = 24) for 3 months.

Main Outcomes And Measures: The primary end point was peak oxygen consumption during upright bicycle ergometry. Secondary end points were 6-minute walk distance, quality of life (Minnesota Living with Heart Failure questionnaire), frequency of ventricular ectopic beats, diastolic function, serum N-terminal pro-brain natriuretic peptide level, and troponin T level.

Results: Of 49 participants who received trimetazidine (n = 26) or placebo (n = 23) and completed the study, 34 (70%) were male; the mean (SD) age was 50 (13) years. Trimetazidine therapy did not improve exercise capacity, with patients in the trimetazidine group walking 38.4 m (95% CI, 5.13 to 71.70 m) less than patients in the placebo group at 3 months after adjustment for their baseline walking distance measurements. After adjustment for baseline values, peak oxygen consumption was 1.35 mL/kg per minute lower (95% CI, -2.58 to -0.11 mL/kg per minute; P = .03) in the intervention group after 3 months.

Conclusions And Relevance: In symptomatic patients with nonobstructive hypertrophic cardiomyopathy, trimetazidine therapy does not improve exercise capacity. Pharmacologic therapy for this disease remains limited.

Trial Registration: ClinicalTrials.gov identifier: NCT01696370.
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http://dx.doi.org/10.1001/jamacardio.2018.4847DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6439550PMC
March 2019

Proteomic Analysis of the Myocardium in Hypertrophic Obstructive Cardiomyopathy.

Circ Genom Precis Med 2018 12;11(12):e001974

University College London Institute of Cardiovascular Science, London, United Kingdom (C.J.C., P.S., T.A.T., J.C.M., L.R.L., C.G.A.M., W.J.M., P.M.E.).

Background: Hypertrophic cardiomyopathy (HCM) is characterized by a complex phenotype that is only partly explained by the biological effects of individual genetic variants. The aim of this study was to use proteomic analysis of myocardial tissue to explore the postgenomic phenotype.

Methods: Label-free proteomic analysis was used initially to compare protein profiles in myocardial samples from 11 patients with HCM undergoing surgical myectomy with control samples from 6 healthy unused donor hearts. Differentially expressed proteins of interest were validated in myocardial samples from 65 unrelated individuals (HCM [n=51], controls [n=7], and aortic stenosis [n=7]) by the development and use of targeted multiple reaction monitoring-based triple quadrupole mass spectrometry.

Results: In this exploratory study, 1586 proteins were identified with 151 proteins differentially expressed in HCM samples compared with controls ( P<0.05). Protein expression profiling showed that many proteins identified in the initial discovery study were associated with metabolism, muscle contraction, calcium regulation, and oxidative stress. Proteins downregulated in HCM versus controls included creatine kinase M-type, fructose-bisphosphate aldolase A, and phosphoglycerate mutase ( P<0.001). Proteins upregulated in HCM included lumican, carbonic anhydrase 3, desmin, α-actin skeletal, and FHL1 (four and a half LIM domain protein 1; P<0.01). Myocardial lumican concentration correlated with the left atrial area (ρ=0.34, P=0.015), late gadolinium enhancement on cardiac magnetic resonance imaging ( P=0.03) and the presence of a pathogenic sarcomere mutation ( P=0.04).

Conclusions: The myocardial proteome of HCM provides supporting evidence for dysregulation of metabolic and structural proteins. The finding that lumican is raised in HCM hearts provides insight into the myocardial fibrosis that characterizes this disease.
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http://dx.doi.org/10.1161/CIRCGEN.117.001974DOI Listing
December 2018

Lamin mutation location predicts cardiac phenotype severity: combined analysis of the published literature.

Open Heart 2018;5(2):e000915. Epub 2018 Oct 25.

Barts Heart Centre, The Cardiovascular Magnetic Resonance Imaging Unit, St Bartholomew's Hospital, London, UK.

Objective: Two genotype-phenotype cardiac correlations are reported: first, that cardiac involvement in multisystem laminopathies prevails with mutations upstream of the nuclear localisation signal (NLS); second, that worse outcomes occur with non-missense (compared with missense) mutations. We tested whether mutation DNA location and mutation subtype can predict phenotype severity in patients with lamin heart disease.

Methods: We used a semantic workflow platform and manual electronic literature search to identify published mutations with cardiac-predominant phenotype. Hierarchical cluster analysis (HCA) assembled lamin heart disease into classes based on phenotype severity. 176 reported causative mutations were classified and any relationships to mutation location/subtype assessed by contingency analysis.

Results: More adverse phenotype was associated with mutation location upstream of the NLS (p=0.014, OR 2.38, 95% CI 1.19 to 4.80) but not with non-missense mutations (p=0.337, OR 1.36, 95% CI 0.72 to 2.57), although an association with non-missense mutations was identified in a subcluster with malignant ventricular arrhythmia (p=0.005, OR 2.64, 95% CI 0.76 to 9.21). HCA limited to the 65 mutations described on ClinVar as pathogenic/likely pathogenic showed similar findings (upstream of NLS, p=0.030, OR 4.78, 95% CI 1.28 to 17.83; non-missense, p=0.121, OR 2.64, 95% CI 0.76 to 9.21) as did analysis limited to pathogenic/likely pathogenic variants according to the American College of Medical Genetics and Genomics standards.

Conclusion: Cardiac patients with an mutation located upstream versus downstream of the NLS have a more adverse cardiac phenotype, and some missense mutations can be as harmful as non-missense ones.
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http://dx.doi.org/10.1136/openhrt-2018-000915DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6203068PMC
October 2018

Ablation compared with drug therapy for recurrent ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy: Results from a multicenter study.

Heart Rhythm 2019 04 24;16(4):536-543. Epub 2018 Oct 24.

Cardiovascular Division, Vanderbilt University Medical Center, Nashville, Tennessee. Electronic address:

Background: The comparative efficacy of antiarrhythmic drug (AAD) therapy vs ventricular tachycardia (VT) ablation in arrhythmogenic right ventricular cardiomyopathy (ARVC) is unknown.

Objective: We compared outcomes of AAD and/or β-blocker (BB) therapy with those of VT ablation (with AAD/BB) in patients with ARVC who had recurrent VT.

Methods: In a multicenter retrospective study, 110 patients with ARVC (mean age 38 ± 17 years; 91[83%] men) with a minimum of 3 VT episodes were included; 77 (70%) were initially treated with AAD/BB and 32 (29%) underwent ablation. Subsequently, 43 of the 77 patients treated with AAD/BB alone also underwent ablation. Overall, 75 patients underwent ablation.

Results: When comparing initial AAD/BB therapy (n = 77) and VT ablation (n = 32) after ≥3 VT episodes, a single ablation procedure rendered 35% of patients free of VT at 3 years compared with 28% of AAD/BB-only-treated patients (P = .46). Of the 77 AAD/BB-only-treated patients, 43 subsequently underwent ablation. For all 75 patients who underwent ablation, 56% were VT-free at 3 years after the last ablation procedure. Epicardial ablation was used in 40/75 (53%) and was associated with lower VT recurrence after the last ablation procedure (endocardial/epicardial vs endocardial-only; 71% vs 47% 3-year VT-free survival; P = .05). Importantly, there was no difference in survival free of death or transplantation between the ablation- and AAD/BB-only-treated patients (P = .61).

Conclusion: In patients with ARVC and a high VT burden, mortality and transplantation-free survival are not significantly different between drug- and ablation-treated patients. These patients have a high risk of recurrent VT despite drug therapy. Combined endocardial/epicardial ablation is associated with reduced VT recurrence as compared with endocardial-only ablation.
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http://dx.doi.org/10.1016/j.hrthm.2018.10.016DOI Listing
April 2019

Ethnic differences in out-of-hospital cardiac arrest among Middle Eastern Arabs and North African populations living in Qatar.

Ethn Health 2018 Oct 10:1-10. Epub 2018 Oct 10.

m Department of Medicine Solna , Karolinska Institutet , Stockholm , Sweden.

Aims: There are very few studies comparing epidemiology and outcomes of out-of-hospital cardiac arrest (OHCA) in different ethnic groups. Previous ethnicity studies have mostly determined OHCA differences between African American and Caucasian populations. The aim of this study was to compare epidemiology, clinical presentation, and outcomes of OHCA between the local Middle Eastern Gulf Cooperation Council (GCC) Arab and the migrant North African populations living in Qatar.

Methods: This was a retrospective cohort study of Middle Eastern GCC Arabs and migrant North African patients with presumed cardiac origin OHCA resuscitated by Emergency Medical Services (EMS) in Qatar, between June 2012 and May 2015.

Results: There were 285 Middle Eastern GCC Arabs and 112 North African OHCA patients enrolled during the study period. Compared with the local GCC Arabs, univariate analysis showed that the migrant North African OHCA patients were younger and had higher odds of initial shockable rhythm, pre-hospital interventions (defibrillation and amioderone), pre-hospital scene time, and decreased odds of risk factors (hypertension, respiratory disease, and diabetes) and pre-hospital response time. The survival to hospital discharge had greater odds for North African OHCA patients which did not persist after adjustment. Multivariable logistic regression showed that North Africans were associated with lower odds of diabetes (OR 0.48, 95% CI 0.25-0.91, p = 0.03), and higher odds of initial shockable rhythm (OR 2.86, 95% CI 1.30-6.33, p = 0.01) and greater scene time (OR 1.02 95% CI 1.0-1.04, p = 0.02).

Conclusions: North African migrant OHCA patients were younger, had decreased risk factors and favourable OHCA rhythm and received greater ACLS interventions with shorter pre-hospital response times and longer scene times leading to better survival.
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http://dx.doi.org/10.1080/13557858.2018.1530736DOI Listing
October 2018

No major role for rare plectin variants in arrhythmogenic right ventricular cardiomyopathy.

PLoS One 2018 30;13(8):e0203078. Epub 2018 Aug 30.

Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.

Aims: Likely pathogenic/pathogenic variants in genes encoding desmosomal proteins play an important role in the pathophysiology of arrhythmogenic right ventricular cardiomyopathy (ARVC). However, for a substantial proportion of ARVC patients, the genetic substrate remains unknown. We hypothesized that plectin, a cytolinker protein encoded by the PLEC gene, could play a role in ARVC because it has been proposed to link the desmosomal protein desmoplakin to the cytoskeleton and therefore has a potential function in the desmosomal structure.

Methods: We screened PLEC in 359 ARVC patients and compared the frequency of rare coding PLEC variants (minor allele frequency [MAF] <0.001) between patients and controls. To assess the frequency of rare variants in the control population, we evaluated the rare coding variants (MAF <0.001) found in the European cohort of the Exome Aggregation Database. We further evaluated plectin localization by immunofluorescence in a subset of patients with and without a PLEC variant.

Results: Forty ARVC patients carried one or more rare PLEC variants (11%, 40/359). However, rare variants also seem to occur frequently in the control population (18%, 4754/26197 individuals). Nor did we find a difference in the prevalence of rare PLEC variants in ARVC patients with or without a desmosomal likely pathogenic/pathogenic variant (14% versus 8%, respectively). However, immunofluorescence analysis did show decreased plectin junctional localization in myocardial tissue from 5 ARVC patients with PLEC variants.

Conclusions: Although PLEC has been hypothesized as a promising candidate gene for ARVC, our current study did not show an enrichment of rare PLEC variants in ARVC patients compared to controls and therefore does not support a major role for PLEC in this disorder. Although rare PLEC variants were associated with abnormal localization in cardiac tissue, the confluence of data does not support a role for plectin abnormalities in ARVC development.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0203078PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6117038PMC
February 2019

Arrhythmogenic right ventricular cardiomyopathy in Boxer dogs: the diagnosis as a link to the human disease.

Acta Myol 2017 Sep 1;36(3):135-150. Epub 2017 Sep 1.

Inherited Cardiovascular Disease Unit, St Bartholomew's Hospital, London, UK.

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a myocardial disease with an increased risk for ventricular arrhythmias. The condition, which occurs in Boxer dogs, shares phenotypic features with the human disease arrhythmogenic cardiomyopathy (ACM) suggesting its potential as a natural animal model. However, there are currently no universally accepted clinical criteria to diagnose ARVC in Boxer dogs. We aimed to identify diagnostic criteria for ARVC in Boxer dogs defining a more uniform and consistent phenotype.

Methods And Results: Clinical records from 264 Boxer dogs from a referral veterinary hospital were retrospectively analysed. ARVC was initially diagnosed according to the number of ventricular premature complexes (VPCs) in the 24-hour-Holter-ECG in the absence of another obvious cause. Dogs diagnosed this way had more VPCs, polymorphic VPCs, couplets, triplets, VTs and R-on-T-phenomenon and syncope, decreased right ventricular function and dilatation in comparison to a control group of all other Boxer dogs seen by the Cardiology Service over the same period. Presence of couplets and R-on-T-phenomenon on a 24h-ECG were identified as independent predictors of the diagnosis. A diagnosis based on ≥100 VPCs in 24 hours, presence of couplets and R-on-T phenomenon on a 24h-ECG was able to select Boxer dogs with a phenotype most similar to human ACM.

Conclusion: We suggest the diagnosis of ARVC in Boxer dogs requires two out of the three following criteria: presence of ≥ 100 VPCs, presence of couplets or R-on-T-phenomenon on a 24 h-ECG. This results in a uniform phenotype similar to that described in human ACM and may result in the adoption of the term ACM for this analogous condition in Boxer dogs.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5953225PMC
September 2017

Lamin and the heart.

Heart 2018 03 25;104(6):468-479. Epub 2017 Nov 25.

Biomedical Research Center, NIHR University College London Hospitals, London, UK.

Lamins A and C are intermediate filament nuclear envelope proteins encoded by the gene. Mutations in cause autosomal dominant severe heart disease, accounting for 10% of dilated cardiomyopathy (DCM). Characterised by progressive conduction system disease, arrhythmia and systolic impairment, lamin A/C heart disease is more malignant than other common DCMs due to high event rates even when the left ventricular impairment is mild. It has several phenotypic mimics, but overall it is likely to be an under-recognised cause of DCM. In certain clinical scenarios, particularly familial DCM with early conduction disease, the pretest probability of finding an mutation may be quite high.Recognising lamin A/C heart disease is important because implantable cardioverter defibrillators need to be implanted early. Promising oral drug therapies are within reach thanks to research into the mitogen-activated protein kinase (MAPK) and affiliated pathways. Personalised heart failure therapy may soon become feasible for , alongside personalised risk stratification, as variant-related differences in phenotype severity and clinical course are being steadily elucidated.Genotyping and family screening are clinically important both to confirm and to exclude mutations, but it is the three-pronged integration of such genetic information with functional data from in vivo cardiomyocyte mechanics, and pathological data from microscopy of the nuclear envelope, that is properly reshaping our knowledge base, one variant at a time. This review explains the biology of lamin A/C heart disease (genetics, structure and function of lamins), clinical presentation (diagnostic pointers, electrocardiographic and imaging features), aspects of screening and management, including current uncertainties, and future directions.
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http://dx.doi.org/10.1136/heartjnl-2017-312338DOI Listing
March 2018

Response by Andrews et al to Letter Regarding Article, "Electrical and Structural Substrate of Arrhythmogenic Right Ventricular Cardiomyopathy Determined Using Noninvasive Electrocardiographic Imaging and Late Gadolinium Magnetic Resonance Imaging".

Circ Arrhythm Electrophysiol 2017 10;10(10)

From the Cardiac Bioelectricity and Arrhythmia Center and Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiovascular Division, Department of Medicine, MO (Y.R.), Washington University in St. Louis, MO; Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.).

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http://dx.doi.org/10.1161/CIRCEP.117.005768DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5687271PMC
October 2017

Classification, Epidemiology, and Global Burden of Cardiomyopathies.

Circ Res 2017 Sep;121(7):722-730

From the Imperial College London, United Kingdom (W.J.M.); Hypertrophic Cardiomyopathy Institute, Division of Cardiology, Tufts Medical Center, Boston, MA (B.J.M.); and Department of Cardiac, Thoracic and Vascular Sciences, University of Padua Medical School, Italy (G.T.).

In the past 25 years, major advances were achieved in the nosography of cardiomyopathies, influencing the definition and taxonomy of this important chapter of cardiovascular disease. Nearly, 50% of patients dying suddenly in childhood or adolescence or undergoing cardiac transplantation are affected by cardiomyopathies. Novel cardiomyopathies have been discovered (arrhythmogenic, restrictive, and noncompacted) and added to update the World Health Organization classification. Myocarditis has also been named inflammatory cardiomyopathy. Extraordinary progress accomplished in molecular genetics of inherited cardiomyopathies allowed establishment of dilated cardiomyopathy as mostly cytoskeleton, force transmission disease; hypertrophic-restrictive cardiomyopathies as sarcomeric, force generation disease; and arrhythmogenic cardiomyopathy as desmosome, cell junction disease. Channelopathies (short and long QT, Brugada, and catecholaminergic polymorphic ventricular tachycardia syndromes) should also be considered cardiomyopathies because of electric myocyte dysfunction. Cardiomyopathies are easily diagnosed but treated only with palliative pharmacological or invasive therapy. Curative therapy, thanks to insights into the molecular pathogenesis, has to target the fundamental mechanisms involved in the onset and progression of these conditions.
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http://dx.doi.org/10.1161/CIRCRESAHA.117.309711DOI Listing
September 2017

Electrical and Structural Substrate of Arrhythmogenic Right Ventricular Cardiomyopathy Determined Using Noninvasive Electrocardiographic Imaging and Late Gadolinium Magnetic Resonance Imaging.

Circ Arrhythm Electrophysiol 2017 Jul;10(7)

From the Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiac Bioelectricity and Arrhythmia Center (C.M.A., Y.R.), Washington University, St. Louis, MO; Department of Medicine, Cardiovascular Division, Washington University in St. Louis, MO (Y.R.); Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.).

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a significant cause of sudden cardiac death in the young. Improved noninvasive assessment of ARVC and better understanding of the disease substrate are important for improving patient outcomes.

Methods And Results: We studied 20 genotyped ARVC patients with a broad spectrum of disease using electrocardiographic imaging (a method for noninvasive cardiac electrophysiology mapping) and advanced late gadolinium enhancement cardiac magnetic resonance scar imaging. Compared with 20 healthy controls, ARVC patients had longer ventricular activation duration (median, 52 versus 42 ms; =0.007) and prolonged mean epicardial activation-recovery intervals (a surrogate for local action potential duration; median, 275 versus 241 ms; =0.014). In these patients, we observed abnormal and varied epicardial activation breakthrough locations and regions of nonuniform conduction and fractionated electrograms. Nonuniform conduction and fractionated electrograms were present in the early concealed phase of ARVC. Electrophysiological abnormalities colocalized with late gadolinium enhancement scar, indicating a relationship with structural disease. Premature ventricular contractions were common in ARVC patients with variable initiation sites in both ventricles. Premature ventricular contraction rate increased with exercise, and within anatomic segments, it correlated with prolonged repolarization, electric markers of scar, and late gadolinium enhancement (all <0.001).

Conclusions: Electrocardiographic imaging reveals electrophysiological substrate properties that differ in ARVC patients compared with healthy controls. A novel mechanistic finding is the presence of repolarization abnormalities in regions where ventricular ectopy originates. The results suggest a potential role for electrocardiographic imaging and late gadolinium enhancement in early diagnosis and noninvasive follow-up of ARVC patients.
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http://dx.doi.org/10.1161/CIRCEP.116.005105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5533087PMC
July 2017

Desmoplakin missense and non-missense mutations in arrhythmogenic right ventricular cardiomyopathy: Genotype-phenotype correlation.

Int J Cardiol 2017 Dec 10;249:268-273. Epub 2017 May 10.

Royal Brompton Hospital, Cardiomyopathy Service, London, United Kingdom. Electronic address:

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is traditionally considered as primarily affecting the right ventricle. Mutations in genes encoding desmosomal proteins account for 40-60% of cases. Genotype-phenotype correlations are scant and mostly non gene-specific. Accordingly, we assessed the genotype-phenotype correlation for desmoplakin (DSP) missense and non-missense mutations causing ARVC.

Methods And Results: We analyzed 27 ARVC patients carrying a missense or a non-missense DSP mutation, with complete clinical assessment. The two groups were compared for clinical parameters, basic demographics such as sex, age at diagnosis, age at disease onset, as well as prevalence of symptoms and arrhythmic events. Missense DSP variants were present in 10 patients and non-missense in 17. Mean age at diagnosis and at first arrhythmic event did not differ between the two groups. Also the prevalence of symptoms, either major (60% vs 59%, p=1) or all (80% vs 88%, p=0.61), did not differ. By contrast, left ventricular (LV) dysfunction was significantly more prevalent among patients with non-missense mutations (76.5% vs 10%, p=0.001), who were also much more likely to have a structural LV involvement by Cardiac Magnetic Resonance (CMR) (92% vs 22%, p=0.001).

Conclusions: For ARVC patients, both missense and non-missense DSP mutations carry a high arrhythmic risk. Non-missense mutations are specifically associated with left-dominant forms. The presence of DSP non-missense mutations should alert to the likely development of LV dysfunction. These findings highlight the clinical relevance of genetic testing even after the clinical diagnosis of ARVC and the growing clinical impact of genetics.
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http://dx.doi.org/10.1016/j.ijcard.2017.05.018DOI Listing
December 2017