Cardiomyopathy in Emery-Dreifuss muscular dystrophy

Article written and reviewed by Dr Luca Moretti

Emery-Dreifuss muscular dystrophy is an inherited disease of skeletal muscle and the heart recognized by the association of early joint contractures, slowly progressive muscle weakness and atrophy, and cardiac involvement. The term does not, however, identify a single cardiomyopathy or one gene: it describes a clinical phenotype caused mainly by abnormalities of EMD or LMNA, but much more rarely by defects in other nuclear proteins. The Emery-Dreifuss triad remains useful for directing diagnosis provided it is not turned into a rigid criterion that excludes incomplete forms.

Cardiac disease is often the prognostically dominant component and may progress independently of weakness. A person who is still ambulatory and has modest joint limitation may develop atrioventricular block, atrial paralysis, cardioembolic stroke, ventricular tachycardia or advanced heart failure; conversely, evident myopathy does not necessarily imply ventricular dysfunction of the same severity. This cardioskeletal dissociation requires cardiology surveillance based on genotype and electrical findings rather than neurologic impression alone.

Electrical disease frequently precedes dilation and reduction in ejection fraction. An apparently well-tolerated bradycardia, low-voltage P waves or modest conduction prolongation are therefore not marginal findings but possible early stages of a progressive process. Recognition of the prestructural phase makes it possible to protect the patient before syncope, embolism or cardiac arrest makes the diagnosis manifest.

Clinical phenotype and correct nosologic definition

Contractures typically appear in childhood and involve the elbows, Achilles tendons and posterior neck muscles, with progressive spinal rigidity. They may precede appreciable loss of strength and cause toe walking, limited elbow extension and reduced cervical flexion. The distribution of contractures, more than their mere presence, distinguishes the picture from many dystrophies in which retractions are late and secondary to loss of ambulation.

Classic weakness begins in humeral and peroneal compartments, with atrophy of the biceps and triceps and involvement of peroneal and anterior tibial muscles; it may later extend to the shoulder and pelvic girdles and axial muscles. Progression is often slow, but severe congenital or childhood-onset disease and subtler adult forms exist. The humeroperoneal phenotype is suggestive but does not replace molecular analysis because numerous nuclear myopathies show clinical overlap.

Cardiac involvement may appear after the second decade, but age is not a biologic barrier and pediatric manifestations are documented. Palpitations, exercise intolerance, presyncope and syncope should be actively sought because patients may attribute them to weakness or immobility. Asymptomatic cardiac disease is also common: low metabolic demand may mask bradycardia and heart failure until reserve is markedly reduced.

Not every carrier of a pathogenic LMNA variant with arrhythmias or cardiomyopathy has Emery-Dreifuss muscular dystrophy. Laminopathies include dilated cardiomyopathy with conduction disease but no myopathy, LMNA-related limb-girdle muscular dystrophy, congenital muscular dystrophy, lipodystrophies and progeroid syndromes. The phenotype-genotype diagnosis must therefore specify whether the muscle-joint triad is present, avoiding use of EDMD as a universal synonym for cardiolaminopathy.

Emerin, lamins and other nuclear-envelope genes

The classic X-linked form results from pathogenic variants in EMD, historically called STA, which encodes emerin. Deletions, nonsense variants, frameshift variants and splice defects generally cause loss of the protein from the inner nuclear membrane; missense variants may preserve variable amounts and complicate phenotype correlation. In hemizygous males, emerin deficiency explains maternal transmission, but de novo variants and mosaicism make family confirmation essential.

Women heterozygous for an EMD variant often lack typical weakness because of mosaic expression determined by X-chromosome inactivation. They are not simply healthy carriers: with age they may develop atrial disease, conduction abnormalities or cardiomyopathy even when muscle examination is normal. Surveillance of heterozygous women must therefore be cardiologic as well as reproductive and cannot depend on the absence of contractures.

LMNA-related forms are more often autosomal dominant and result from variants affecting lamins A and C, intermediate filaments of the nuclear lamina produced by alternative splicing. Rare autosomal recessive forms also exist, generally with earlier onset and a prominent muscle phenotype. The laminopathy continuum explains why the same family may include EDMD, limb-girdle myopathy and nearly isolated cardiomyopathy without these labels representing separate molecular diseases.

FHL1 variants may cause an X-linked form with contractures and an Emery-Dreifuss-like myopathy, sometimes within a spectrum including reducing-body myopathy and scapuloperoneal myopathy. Very rare associations have been described for SUN1, SUN2, SYNE1, SYNE2 and TMEM43, which encode components or partners of the nuclear envelope and LINC complex. Gene-disease evidence and cardiac risk are not identical for all these genes, so a rare variant should not be declared causal without rigorous classification and family consistency.

A broad panel may identify variants in genes for myofibrillar myopathies or dystrophies with contractures, including DES, VCP, TOR1AIP1 and others, but clinical resemblance does not automatically make them EDMD subtypes. Immunohistochemistry for emerin and lamin A/C may support interpretation, especially when emerin is absent, while apparently normal expression does not exclude a dysfunctional protein. Nonprescriptive genetics starts from the phenotype and applies pathogenicity criteria rather than adapting the patient to every sequencing result.

Pathogenesis of cardiac disease

Emerin, lamins and nesprins form a network linking chromatin, nuclear lamina, nuclear membrane and cytoskeleton. In cardiomyocytes subjected to cyclical deformation, this system distributes stress and contributes to nuclear position, DNA repair and transcriptional regulation. A defect in nuclear mechanics makes continuously stressed tissues such as myocardium, the conduction system and skeletal muscle particularly vulnerable.

A purely mechanical model does not by itself explain phenotypic selectivity. Abnormal chromatin organization, MAPK signaling, stress responses, autophagy and cell differentiation contribute to cardiomyocyte loss and fibro-adipose replacement. Mechanotranscriptional dysregulation therefore integrates structural fragility and gene expression, but no single pathway has yet produced an approved causal therapy in humans.

Fibrosis does not involve the heart uniformly. In emerin disease, progressive rarefaction of atrial myocardium may dominate, whereas LMNA laminopathies frequently show atrioventricular disease, septal scar and ventricular impairment. The topography of fibrosis explains the clinical sequence in which atrial arrhythmias and blocks precede dilated cardiomyopathy recognizable by conventional imaging.

Cardiac severity does not follow CK level, strength or degree of contractures linearly. Genetic modifiers, variant type and position, sex, age and acquired factors contribute to penetrance, while overly confident individual correlations remain inappropriate. Intrafamilial variability justifies screening every at-risk relative even when the proband has an apparently mild and uniform phenotype.

Atrial disease, atrial standstill and conduction disturbances

The earliest abnormalities may be sinus bradycardia, small or broad P waves, PR prolongation and intraventricular delays. With progression, sinus-node dysfunction, increasing degrees of atrioventricular block and escape rhythms develop, sometimes before any ventricular dilation. Electrical progression makes a normal ECG obtained years earlier insufficient and requires serial comparison of intervals and morphology.

Atrial fibrillation and flutter are common and may present with a slow ventricular response because of concomitant conduction disease. A nonrapid rate does not make the arrhythmia benign: loss of atrial systole, stasis and low output may cause fatigue, syncope or embolism. The atrial phenotype should be sought with prolonged monitoring when palpitations, an irregular pulse or functional worsening are unexplained by an occasional ECG.

Atrial standstill is loss of atrial electrical and mechanical activity and may be partial, regional or complete. ECG shows absent P waves with a junctional or ventricular rhythm, imaging documents absent atrial contraction, and electrophysiologic study may demonstrate minimal atrial electrograms and failure to capture even at high output. Atrial paralysis is not the same as atrial fibrillation with a slow response or transient sinus arrest and may represent the end stage of atrial myopathy.

Loss of atrial contraction creates an important thrombogenic substrate, especially in the left atrium and appendage, and stroke may be the first cardiac manifestation in a young person. HRS consensus recommends anticoagulation with atrial fibrillation or flutter and also with atrial standstill, considering bleeding risk; a low CHA2DS2-VASc score does not neutralize disease-specific risk. Cardioembolic prevention should therefore follow the actual atrial phenotype rather than waiting for a neurologic event.

Atrial disease also affects device selection. An atrial lead may fail to find capturable tissue, making effective dual-chamber pacing impossible; mapping, imaging and capture testing help define the strategy. Individualized pacing considers residual rhythm, chronotropic competence, ventricular need and probability of progression rather than assuming that every bradycardia requires the same configuration.

Ventricular cardiomyopathy and arrhythmic risk

The ventricular component may begin with mild dilation, regional abnormalities, reduced strain or fibrosis on CMR and progress to dilated cardiomyopathy with systolic dysfunction. In LMNA, conduction disease and arrhythmias often precede ejection-fraction decline by years, so apparently preserved function does not equal low risk. The early electrical phenotype distinguishes this cardiomyopathy from many forms in which risk rises mainly after severe ventricular dysfunction.

Nonsustained ventricular tachycardia, sustained monomorphic tachycardia and ventricular fibrillation may arise on a scar substrate. Unexplained syncope, conduction disturbances, male sex, type of LMNA variant, ventricular arrhythmias and systolic function contribute to stratification, but no single indicator exhausts risk. LMNA sudden death may occur with ejection fraction above the traditional 35% threshold, making mechanical application of common heart-failure criteria inadequate.

The LMNA-risk VTA model estimates five-year risk of potentially life-threatening ventricular tachyarrhythmia by integrating sex, non-missense variant, atrioventricular block, nonsustained ventricular tachycardia and ejection fraction as a continuous variable. It was developed and validated in adult carriers of LMNA variants, not as a general calculator for all forms of EDMD. The LMNA-specific estimate supports ICD decisions together with guidelines, family history, CMR, comorbidities and preferences.

The older belief that EMD disease causes only bradyarrhythmias and that a pacemaker eliminates risk is too reassuring. Recent longitudinal data also document malignant ventricular arrhythmias, systolic dysfunction and end-stage heart failure in males with EDMD1; the average profile may differ from LMNA, but this does not justify limiting protection to rate alone. EMD ventricular risk should be reassessed when dysfunction, fibrosis, arrhythmias or an unfavorable family history appear.

Heart failure may present with congestion, low output and functional decline, but dyspnea and reduced exercise tolerance can be confounded by weakness, chest stiffness and deconditioning. Weight, edema, venous pressure, natriuretic peptides and imaging help separate components without attributing every symptom to the dystrophy. Integrated hemodynamic assessment is necessary because a walking-based NYHA class loses precision in a patient with neuromuscular limitation.

Clinical, instrumental and differential diagnosis

Diagnosis begins with a history reconstructing age at onset of contractures, distribution of weakness, loss of abilities, cardiac and respiratory symptoms, and a pedigree extending at least three generations. Sudden deaths, early pacemakers, young strokes, transplants and relatives with a purely cardiac diagnosis are as important as known muscular dystrophies. A cardiomuscular pedigree may reveal X-linked or dominant inheritance hidden by different labels assigned to relatives.

Examination assesses elbow extension, ankle dorsiflexion, cervical and spinal mobility, humeral, peroneal, scapular, pelvic and axial strength, gait and scoliosis. CK is often normal or moderately elevated and does not measure cardiac severity; electromyography and biopsy may show myopathy but are rarely specific. Neuromuscular phenotyping guides genetic testing and permits interpretation of a variant that would remain uncertain outside the clinical context.

Initial cardiac assessment includes targeted history, examination, ECG, ambulatory monitoring and imaging with echocardiography or magnetic resonance. Echocardiography measures volumes, ejection fraction, right ventricular function, valves and strain when available; magnetic resonance characterizes function and fibrosis and may clarify an early phenotype. Multimodal diagnosis is superior to a single test because electrical activity, scar and function do not necessarily evolve at the same time.

Sequencing should include sequence variants and, when relevant, deletions or duplications, which are particularly important in EMD. A coherent pathogenic or likely pathogenic result confirms etiology; a variant of uncertain significance should not guide device implantation in healthy relatives or prenatal diagnosis. Variant classification requires segregation, population frequency, functional data and periodic review, especially in genes rarely associated with the phenotype.

The differential diagnosis includes myotonic dystrophy, limb-girdle dystrophies, collagen VI myopathies, desminopathies, FHL1-related dystrophies, Bethlem myopathy, Ullrich disease and other myopathies with spinal rigidity. Cardiomyopathy with block may also result from DES, FLNC, DSP, RBM20 or sarcoidosis without constituting EDMD. A domain-based differential compares contractures, muscle distribution, conduction, arrhythmias, imaging and inheritance rather than relying on one similarity.

Lifelong cardiology surveillance

Once diagnosis is established, ECG, ambulatory monitoring and imaging are repeated periodically even without symptoms. Annual assessment is often the reference interval in established forms, but conduction abnormalities, arrhythmias, dysfunction, the age of familial risk or symptoms require shorter intervals. Dynamic surveillance is not an immutable calendar: it is intensified when the trajectory changes, not only when a threshold is crossed.

Monitoring for 24 or 48 hours may miss sporadic events. Longer external recorders or implantable loop recorders are reasonable with unexplained syncope, presyncope or palpitations despite normal conventional testing, whereas electrophysiologic study is selective for defining His-Purkinje conduction and arrhythmias. Monitoring duration should match symptom frequency and risk, without confusing a negative Holter with absence of disease.

On CMR, midmyocardial septal fibrosis may accompany laminopathies and provide additional information, but its absence does not eliminate electrical risk. After implantation, MRI-compatible devices are chosen when possible and access to future imaging is preserved through appropriate protocols. Imaging continuity should be considered at device selection because patients will be followed for decades and may develop dysfunction after implantation.

Each visit also checks blood pressure, signs of congestion, renal function, electrolytes, natriuretic peptides when useful, adherence, anticoagulation and device data. Remote monitoring may identify arrhythmias, increased pacing burden or ICD therapies but does not replace clinical examination and neuromuscular assessment. Multidomain surveillance links electrical and structural data to respiratory capacity and the technical feasibility of a potential intervention.

Family genetics and presymptomatic diagnosis

In X-linked EMD disease, a heterozygous woman has a 50% probability of transmitting the variant in each pregnancy; sons who inherit it are hemizygous and daughters become heterozygous with mainly cardiac risk. An affected male transmits the variant to all daughters and to no sons. X-linked counseling should include the possibility of de novo variants, germline mosaicism and manifestations in women, avoiding absolute formulas such as asymptomatic carrier.

An autosomal dominant LMNA variant carries a 50% transmission risk for each child regardless of sex; rare recessive forms instead require analysis of both alleles and the partner. Targeted testing for the familial variant allows noncarriers to be discharged from disease-specific surveillance and carriers to be followed early even without muscle signs. The genetic cascade prevents cardiac events in people who would not otherwise have attended a neuromuscular center.

First-degree relatives who cannot or do not wish to undergo testing should receive at least clinical screening, ECG and periodic imaging. In minors, testing has concrete benefit because cardiac manifestations may appear before adulthood and surveillance changes management. Presymptomatic diagnosis requires age-appropriate consent, psychological support and a clear explanation that incomplete penetrance does not mean absence of future risk.

Anticoagulation, pacemaker and defibrillator

Atrial fibrillation, flutter and atrial standstill require a timely anticoagulation decision. Bleeding risk, renal function, interactions, falls and procedures are assessed, but young age and a low conventional thromboembolic score should not lead to neglect of disease-specific atrial stasis. Choice among oral anticoagulants follows general indications and individual characteristics because there are no randomized EDMD-specific trials showing superiority of one drug.

A pacemaker is indicated when bradycardia or block meets clinical and electrophysiologic criteria, but it resolves only the slow component. In an LMNA carrier and other EDMD phenotypes with significant ventricular risk, the first implantation should include explicit assessment for an ICD because later revision requires new procedures and a pacemaker does not treat ventricular fibrillation. Choice of the first device is therefore a prognostic decision, not a technical detail subordinate to the block.

HRS consensus recommends an ICD with pacing capability in survivors of hemodynamically relevant sustained ventricular tachycardia or ventricular fibrillation, in dysfunction with ejection fraction no greater than 35% despite therapy, and when at least one of the following is documented: second- or third-degree atrioventricular block, PR not less than 230 ms, or spontaneous HV interval not less than 70 ms. It also considers an ICD reasonable with nonsustained ventricular tachycardia plus ejection fraction below 45%, or right or left bundle branch block, or atrial fibrillation or flutter with ventricular rate below 50 beats per minute. These recommendations derive mainly from observational data and should be applied according to clinical status and goals of care. Device stratification remains shared and considers age, access, infection, life expectancy and patient preferences.

A subcutaneous ICD does not provide continuous antibradycardia pacing or antitachycardia pacing and is therefore often poorly suited to a disease with a high likelihood of block. If a substantial burden of right ventricular pacing is expected or dysfunction, bundle branch block and dyssynchrony criteria are present, resynchronization with or without a defibrillator is considered according to the arrhythmic profile. Prevention of dyssynchrony matters because pacing cardiomyopathy may overlap with the genetic process and accelerate decline.

Device programming should balance protection, inappropriate therapies, capture and battery longevity. Remote and in-person checks assess thresholds, atrial arrhythmias, ventricular tachycardias, pacing percentage and signs of failure; anticoagulation and cardioversion are coordinated with residual atrial activity. Post-implant management continues for life and includes planning replacements, venous access, infection risk and early discussion of preferences in advanced stages.

Heart failure and multidisciplinary care

Ventricular dysfunction is treated with guideline-based heart-failure therapy, including as indicated renin-angiotensin system inhibition or ARNI, beta-blocker, mineralocorticoid receptor antagonist and SGLT2 inhibitor. There are no large EDMD-specific trials, so efficacy and tolerability are extrapolated from nonischemic cardiomyopathy; bradycardia, low blood pressure, renal function and pacing status require careful titration. Adapted quadruple therapy should not be withheld because of myopathy, but neither should it be applied without considering conduction and frailty.

Ejection fraction may decline despite therapy and devices. Early referral to an advanced heart-failure center permits evaluation of mechanical support and transplantation before malnutrition, respiratory failure or organ dysfunction eliminates options; EDMD is not itself a contraindication to transplantation. Early transplant assessment integrates independence, respiratory strength, swallowing, rehabilitation potential and family support rather than using the neuromuscular label alone.

The neuromuscular component requires physiatry, neurology, orthopedics and physiotherapy. Regular stretching and orthoses may slow retractions, while tenotomies or scoliosis correction are planned according to function, goals and cardiopulmonary risk; excessive immobilization promotes loss of strength. Contracture care preserves posture, transfers and ventilation but should not divert attention from silent cardiac disease.

Spinal rigidity, scoliosis and axial weakness may cause restrictive ventilatory impairment even when limb strength is relatively preserved. Sitting and supine spirometry, inspiratory pressures, peak cough flow and overnight studies identify hypoventilation and ineffective cough; noninvasive ventilation and mechanical assistance are introduced according to physiology and symptoms. Respiratory reserve affects prognosis, device-implant safety, transplant candidacy and recovery after every procedure.

Physical activity is prescribed individually at moderate intensity, with adequate recovery and attention to pain, prolonged fatigue and arrhythmias. Extreme or competitive exercise is generally inappropriate when cardiomyopathy, fibrosis, arrhythmias or a high-risk laminopathy are present, whereas absolute inactivity accelerates deconditioning and loss of independence. Cardiomuscular rehabilitation uses limits defined by rhythm, function, strength and ventilation rather than a generic prohibition for everyone.

Anesthesia, pregnancy and special situations

Before anesthesia or sedation, ECG, ventricular function, arrhythmias, device, anticoagulation, ventilatory capacity, cough, swallowing and cervical mobility are reviewed. Contractures and rigidity may complicate positioning and airway management, while depressant drugs and postoperative pain reduce already marginal ventilation. Anesthetic planning requires an environment capable of pacing, defibrillation and respiratory support even for apparently minor procedures.

As in other muscular dystrophies, succinylcholine is avoided because of the risk of hyperkalemia and rhabdomyolysis; drug strategy is defined by an experienced anesthesiologist rather than a diagnostic automatic rule. EDMD should not be declared definite susceptibility to malignant hyperthermia without specific evidence, but this distinction does not eliminate real cardiac and respiratory risks. Precision of anesthetic risk avoids both inappropriate reassurance and unproven labels that unnecessarily complicate care.

During pregnancy, circulating volume, heart rate and ventilatory demand increase, with possible emergence of arrhythmias or heart failure. Preconception counseling assesses gene, function, rhythm, device, potentially teratogenic drugs, anticoagulant, respiratory strength and mode of delivery; cardiology, maternal-fetal medicine, genetics and anesthesia agree on a plan. Pregnancy in laminopathies cannot be judged by ventricular diameter alone or transmission risk alone.

Fever, dehydration, infections and electrolyte abnormalities may destabilize conduction and arrhythmias, while bed rest and interruption of anticoagulation increase thrombotic risk. An emergency plan records the molecular diagnosis, baseline rhythm, pacing dependency, device type, anticoagulant therapy and center contacts. Continuity in emergencies prevents a known junctional rhythm from being mistaken for an incidental finding or a pacemaker from being assumed to provide complete protection from sudden death.

Prognosis and therapeutic perspectives

In many patients, prognosis is determined more by cardiac disease than by the pace of loss of ambulation. Late diagnosis, unanticoagulated atrial arrhythmias, unprotected block, ventricular tachycardias, progressive dysfunction and respiratory failure worsen outcomes, while family screening and appropriate devices make many events preventable. Contemporary prognosis does not match the natural history of unmonitored cohorts but remains serious even in the era of ICDs and heart-failure therapy.

In an asymptomatic carrier, risk is neither uniform nor immediate, and proportionate surveillance is preferable to indiscriminate medicalization. The goal is to recognize transition from genotype to phenotype through serial changes in conduction, rhythm, imaging and biomarkers, without implanting devices solely because of a VUS or promising safety based on one normal examination. The individual trajectory gains meaning when compared with the gene, family and prior measurements.

Cellular, animal and pluripotent-cell-derived models are studying gene correction, modulation of stress pathways, restoration of the nuclear envelope and prevention of fibrosis. These strategies remain experimental, and the diversity among emerin loss, dominant lamin A/C abnormalities and LINC-complex defects makes a single therapy for all EDMD unlikely. Causal research will need to demonstrate durable effects on arrhythmias, conduction, myocardium and muscle, not merely normalize a cellular marker.

Optimal management brings together a cardiomyopathy cardiologist, electrophysiologist, neurologist, geneticist, pulmonologist, physiatrist, anesthesiologist and advanced heart-failure center. A shared registry of genotype, ECG, monitoring, imaging, respiratory function, devices and events prevents each specialist from seeing only one fragment and underestimating the rest. Multidisciplinary medicine is a concrete prognostic intervention in this disease because it turns early, dispersed signals into timely and coherent decisions.