Duchenne Muscular Dystrophy: Detecting and Treating Arrhythmia

Duchenne muscular dystrophy (DMD) is best known for progressive skeletal muscle weakness, yet cardiac involvement is a major cause of illness and premature death. Myocardial fibrosis, ventricular dysfunction and electrical instability can develop before symptoms appear, making surveillance an essential part of lifelong care.

Arrhythmias in DMD are shaped by the underlying cardiomyopathy, the effects of dystrophin deficiency on cardiac cells, respiratory disease, medications and reduced mobility. A normal examination or absence of palpitations does not reliably exclude clinically important disease, particularly in children and young adults who may have limited exercise capacity.

For Australian clinicians, effective management depends on coordinated care between paediatricians, neurologists, cardiologists, electrophysiologists, respiratory teams and allied health professionals. Screening should be accessible across metropolitan services such as Sydney, Melbourne, Brisbane and Perth, while telehealth and shared-care pathways can help families living in regional and remote communities.

Why dystrophin deficiency causes electrical instability

Dystrophin supports the structural connection between the cardiomyocyte membrane and the surrounding cytoskeleton. In DMD, its absence increases membrane vulnerability and disrupts mechanical force transmission. Repeated cellular injury leads to inflammation, replacement fibrosis and progressive loss of functional myocardium.

Fibrosis often begins in the posterolateral or inferolateral left ventricular wall before global systolic impairment becomes obvious. Scar tissue creates areas of conduction slowing and electrical heterogeneity, providing a substrate for ventricular ectopy, non-sustained ventricular tachycardia and, in advanced disease, sustained ventricular arrhythmia. The relationship between scar burden and arrhythmic risk is clinically important even when the ejection fraction remains relatively preserved.

Electrical disease may also involve the atria and conduction system. Sinus tachycardia, atrial ectopy, atrial tachycardia and atrial fibrillation can occur, although ventricular arrhythmias and progressive heart failure usually receive greater attention. Sinus node or atrioventricular node dysfunction is less characteristic than myocardial scar, but bradyarrhythmia should be considered when symptoms, medications or advanced cardiomyopathy suggest it.

Early cardiac screening in children and adolescents

Cardiac assessment should begin at diagnosis or early in childhood, rather than waiting for weakness, chest discomfort or breathlessness to worsen. A baseline 12-lead ECG and echocardiogram establish a reference point. Serial ECGs may reveal increasing repolarisation abnormalities, conduction changes or atrial and ventricular ectopy, while echocardiography assesses chamber size, wall motion and systolic function.

Many expert pathways recommend at least annual cardiac review from around six years of age, with shorter intervals when abnormalities are present. The exact schedule should reflect age, genotype, imaging findings, symptoms and treatment. Children taking corticosteroids may have altered body composition and blood pressure, so cardiovascular assessment should sit within the broader DMD review rather than rely on a single measurement.

Ambulatory monitoring is useful when there are palpitations, syncope, unexplained fatigue, frequent ectopic beats or concerning ECG findings. A 24-hour Holter monitor may miss intermittent events; longer patch monitoring can improve detection when symptoms are infrequent. Exercise testing is often limited by skeletal muscle weakness and should be individualised, with respiratory status and falls risk considered.

Imaging reveals disease before symptoms

Echocardiography remains widely available and practical, but image quality can be limited by scoliosis, chest shape, contractures or poor acoustic windows. Strain imaging may identify subtle left ventricular dysfunction before a fall in ejection fraction. This is valuable because treatment may be more effective when begun before advanced remodeling develops.

Cardiac magnetic resonance imaging (CMR) provides a stronger assessment of ventricular volumes, function and myocardial tissue. Late gadolinium enhancement can demonstrate replacement fibrosis, while T1 mapping and extracellular volume estimation may identify diffuse myocardial abnormalities. CMR findings can support risk assessment when an echocardiogram appears reassuring, although sedation, scanner access and the need to remain still can complicate testing in younger patients.

In Australia, access to CMR is uneven between tertiary hospitals and smaller regional centres. Referral planning should account for travel, wheelchair transport, respiratory support and the family’s capacity to attend repeated appointments. Imaging protocols should be interpreted by teams familiar with neuromuscular cardiomyopathy, since modest changes over time may carry greater significance than a single isolated value.

Monitoring palpitations and silent arrhythmia

Symptoms in DMD can be difficult to interpret. Palpitations may reflect sinus tachycardia, anxiety, dehydration, infection, anaemia or medication effects rather than a primary rhythm disorder. Conversely, limited mobility may mask exertional symptoms, and some patients do not recognise brief episodes of tachycardia. Syncope, near-syncope, new chest discomfort and an abrupt decline in function require prompt assessment.

Holter monitoring, event recorders and implantable loop recorders can be selected according to symptom frequency and clinical risk. Device-detected atrial high-rate episodes should be interpreted carefully, as artefact and short self-terminating episodes do not automatically establish atrial fibrillation or justify anticoagulation. Lessons from broader device populations, including atrial fibrillation screening, reinforce the importance of confirming the rhythm and weighing episode duration against individual stroke and bleeding risks.

Remote follow-up is particularly useful for people who have an implanted pacemaker, defibrillator or loop recorder. It can identify lead problems, battery depletion and stored arrhythmia episodes between clinic visits. The Journal of Arrhythmia discussion of remote device monitoring is relevant to services building hybrid models of in-person and virtual care.

Medicines that modify cardiac risk

Neurohormonal therapy is commonly considered when left ventricular dysfunction or myocardial fibrosis is identified. Angiotensin-converting enzyme inhibitors or angiotensin receptor blockers may reduce ventricular remodeling, while mineralocorticoid receptor antagonists such as eplerenone can be considered in selected patients. Beta blockers are useful for systolic dysfunction, symptomatic tachyarrhythmia or high adrenergic drive, but bradycardia, fatigue, hypotension and respiratory status must be monitored.

Evidence supports starting cardioprotective therapy before severe systolic impairment in many patients with DMD, although timing and drug selection require specialist judgement. Renal function, potassium, blood pressure and interactions with other medicines should be reviewed regularly. Corticosteroids can influence blood pressure, glucose, weight and infection risk, all of which affect cardiovascular management.

Atrial fibrillation or atrial flutter requires an individualised approach to rate control, rhythm control and anticoagulation. Standard stroke-risk scores may not capture every factor relevant to DMD, while immobility, falls, respiratory disease and planned procedures can alter bleeding risk. Anticoagulation decisions should be made with the cardiology and neuromuscular teams, not from device detection alone.

When ablation or an implanted device is appropriate

Catheter ablation may be appropriate for recurrent, symptomatic or sustained supraventricular tachycardia, and occasionally for selected ventricular arrhythmias. Procedural planning should include anaesthetic review because respiratory muscle weakness, difficult airway management, scoliosis and postoperative ventilation needs can materially change risk. Electrophysiology procedures should be undertaken in centres equipped to manage complex neuromuscular patients.

Implantable cardioverter-defibrillator (ICD) decisions are especially challenging. A reduced ejection fraction, extensive CMR fibrosis, sustained ventricular tachycardia or resuscitated cardiac arrest may support consideration, but DMD-specific evidence is limited. Competing risks include infection, lead complications, inappropriate shocks, venous access problems and the physical burden of a device in a patient with progressive weakness.

Pacing is indicated for clinically significant bradycardia or atrioventricular block, while cardiac resynchronisation therapy may be considered in selected patients with ventricular dyssynchrony and heart failure. The choice between transvenous and subcutaneous systems depends on anatomy, pacing requirements, infection risk and anticipated future access. Shared decision-making should include the patient’s goals, communication needs and likely progression of respiratory and skeletal muscle disease.

Building an Australian care pathway

Australia’s health system requires practical coordination across Medicare-funded specialist care, public hospital services, private cardiology, state-based children’s hospitals and the National Disability Insurance Scheme (NDIS). NDIS supports may assist with transport, communication, equipment and daily living, but they do not replace medical surveillance. Clear documentation helps families and care coordinators distinguish clinical cardiology needs from disability supports.

The Therapeutic Goods Administration (TGA) regulates medicines and medical devices available in Australia, while local hospital formularies and reimbursement arrangements influence access. A therapy used overseas may require careful discussion about Australian approval, subsidy and specialist supply. Privacy obligations under Australian law also matter when ECGs, implantable-device data and telehealth records move between hospitals, community clinicians and commercial monitoring platforms.

Everyday realities affect adherence. Long travel from regional New South Wales or Western Australia, school schedules, wheelchair-accessible accommodation and the need for a carer can turn a short review into a major family commitment. Coordinated appointments, local ECG recording, shared electronic records and remote device checks can reduce that burden without weakening specialist oversight.

Families should receive an emergency plan describing warning symptoms, current medicines, baseline cardiac findings and the treating cardiology service. Clinicians caring for DMD should document genotype, ventricular function, fibrosis, rhythm history and respiratory status in a form that can be rapidly understood by emergency departments in Melbourne, Adelaide, Darwin or elsewhere. Specialist teams can contact the journal to engage with current electrophysiology research, educational resources and opportunities for scholarly collaboration.

Early surveillance gives clinicians more choices: preventive medication, closer rhythm monitoring, targeted electrophysiology review and timely discussion of advanced therapies. Australian neuromuscular and cardiac services can strengthen outcomes by embedding ECG, echocardiography, CMR, ambulatory monitoring and family education into a coordinated pathway from childhood through adult care. Publish and share local data, apply evidence carefully to each patient, and make arrhythmia prevention a routine part of DMD management.