The Heart and Muscular Dystrophy: Surveillance and Treatment

The heart and muscular dystrophy: the organ that decides the outcome

The heart is a muscle, and in most of the muscular dystrophies it is affected.

That one fact is the most important thing in this group of conditions and the one most often not acted on, because of a pattern that recurs across several types: cardiac involvement does not track limb weakness. A man with Becker muscular dystrophy who is still working and walking can have significant dilated cardiomyopathy. Somebody with myotonic dystrophy whose muscle symptoms are mild can have a conduction defect capable of causing sudden death. A person with Emery-Dreifuss muscular dystrophy may need a pacemaker while their weakness is barely noticeable.

So the mental model that says “my muscle disease is mild, therefore my heart is fine” is wrong, and it is wrong in a way that kills people.

The corresponding good news is that cardiac involvement in muscular dystrophy is now monitored and treated before it causes symptoms, and that this is one of the main reasons survival figures have moved. The Australian 50-year Duchenne cohort study published in 2025 found that alongside corticosteroids and respiratory support, increased use of ACE inhibitors and echocardiography accompanied median survival rising from 18.2 to 24.0 years.

This guide covers what happens to the heart in muscular dystrophy, the surveillance schedule by type, the medication, what female carriers need, and the practical business of making sure the appointments actually happen.

What goes wrong, and the two different problems

Cardiac involvement in muscular dystrophy takes two broadly different forms, and which one you are at risk of depends on your diagnosis.

Cardiomyopathy — a pump problem. The heart muscle itself is affected, becomes weaker, and the chambers dilate. The ejection fraction falls. Eventually this produces heart failure: breathlessness, fatigue, fluid retention, exercise intolerance. This is the dominant pattern in Duchenne and Becker muscular dystrophy, and it occurs in several limb-girdle subtypes.

Conduction disease — an electrical problem. The system that carries the electrical signal through the heart develops blocks and the rhythm becomes unreliable. Heart block, bundle branch block, atrial fibrillation and flutter, and ventricular arrhythmias. The danger here is different: not gradual failure but sudden death, sometimes as the first event. This is the dominant pattern in myotonic dystrophy and in Emery-Dreifuss muscular dystrophy, and it is also why the lamin A/C-related conditions are treated with particular seriousness.

Many people have both, and the distinction matters because the surveillance differs. Cardiomyopathy is detected by imaging — echocardiography or cardiac MRI. Conduction disease is detected by ECG and Holter monitoring, and an echocardiogram alone will miss it.

That is worth repeating, because it is a common and consequential error: a normal echocardiogram does not exclude dangerous conduction disease. Somebody with myotonic dystrophy who has had an echo and been reassured has not been adequately assessed.

One more thing worth knowing. In the dystrophinopathies, fibrosis in the heart muscle appears before the ejection fraction falls, and cardiac MRI detects it when echocardiography cannot. That is why the modern protocols move from echo to MRI in later childhood — it allows treatment to start earlier.

The surveillance schedule, by type

Duchenne muscular dystrophy. From the 2018 international care considerations:

• Baseline evaluation at diagnosis, including ECG and non-invasive imaging
• Echocardiography until about age 6 to 7, then cardiac MRI, which can usually be performed without anaesthesia from that age
• Annual assessment until age 10; after 10, at least annual assessment in asymptomatic patients
• ACE inhibitors or ARBs recommended by age 10, before any symptom; earlier use in asymptomatic boys at cardiologist discretion after discussing risks and benefits with the family
• Start at any age once heart failure symptoms or imaging abnormalities appear
• Consider annual Holter monitoring once left ventricular dysfunction or myocardial fibrosis develops
• Cardiology consultation before any surgery, including spinal surgery

Becker muscular dystrophy. Baseline assessment at diagnosis and regular ongoing review, at least annually once any abnormality appears, with imaging. The essential point is that surveillance must continue regardless of how good the limb function is, because the two are disconnected. Some men with Becker present to cardiology with heart failure before anybody has diagnosed a muscle disease.

Myotonic dystrophy types 1 and 2. An annual ECG is the core recommendation, to detect asymptomatic conduction defects. Some centres also perform annual 24-hour Holter monitoring in people without cardiac symptoms. Anybody with syncope, palpitations or chest pain needs an ECG and Holter, with echocardiography and cardiology referral considered. Conduction defects have been found in around 90 per cent of people with DM1 in some series and are a major cause of early death including sudden death; pacemakers are sometimes needed, and in some people an implantable defibrillator. Atrial fibrillation also raises stroke risk and needs managing on its own terms. See myotonic dystrophy.

Emery-Dreifuss muscular dystrophy. Cardiology involvement from diagnosis, with ECG, Holter monitoring and imaging, and ongoing surveillance. Conduction disease frequently requires a pacemaker and sometimes a defibrillator, and it can be the first and most dangerous manifestation. The lamin A/C forms carry significant arrhythmia and cardiomyopathy risk, and first-degree relatives should be assessed, because a relative who looks unaffected can still carry arrhythmia risk.

Limb-girdle muscular dystrophies. Entirely subtype-dependent. Some subtypes carry substantial cardiac risk and some carry essentially none, and which is which is specific knowledge. This is the strongest practical argument for identifying your exact subtype — a surveillance plan cannot be written for “limb-girdle muscular dystrophy.” See Becker, limb-girdle and FSHD.

FSHD. Cardiac involvement is generally not a major feature, which is a real difference from the other types. It does not mean cardiac symptoms should be dismissed.

Congenital muscular dystrophies. Subtype-dependent, with some carrying significant risk.

Medication, and why it starts before symptoms

The thing that is genuinely unusual about cardiac care in muscular dystrophy, and worth understanding properly, is that medication is started in an organ that has not yet failed.

ACE inhibitors or angiotensin receptor blockers. Recommended by age 10 in boys with Duchenne, on the basis that starting before measurable dysfunction appears slows the development of cardiomyopathy. There is also a body of work arguing for starting earlier still. This is prophylaxis, and from a family’s perspective it can feel like medicating a well child — which it is, and which is the point.

Beta blockers, added where there is left ventricular dysfunction.

Mineralocorticoid receptor antagonists such as spironolactone or eplerenone, which have evidence in dystrophinopathy cardiomyopathy.

Standard heart failure management where heart failure develops, under a cardiologist.

Anticoagulation where atrial fibrillation is present, because of stroke risk — particularly relevant in myotonic dystrophy.

Pacemakers and implantable defibrillators, in the conduction-disease types.

And a caution. Several medications used elsewhere require care in muscular dystrophy. Statins can cause muscle symptoms and are generally avoided in myotonic dystrophy. Any new medication is worth checking against the muscle condition, and your neuromuscular clinic is the place to ask.

Female carriers

This is the most frequently overlooked group in the whole of muscular dystrophy care.

Women who carry a dystrophin variant — the mothers, sisters and daughters in Duchenne and Becker families — are usually described as unaffected carriers. A proportion of them have cardiac involvement, and some have skeletal muscle symptoms as well.

The 2018 care considerations recommend that female carriers have a baseline ECG and imaging, preferably cardiac MRI, in early adulthood, and if negative, repeat assessment every three to five years.

Very few Australian carrier women are getting that. The usual experience is of being tested to establish carrier status for reproductive reasons, told the result, and discharged — with no cardiac follow-up arranged and no mention that any would be needed.

If you are a known or possible carrier in a Duchenne or Becker family, this applies to you. Ask your GP for a referral for baseline cardiac assessment and tell them the guideline recommendation. If you have never been tested for carrier status, that is a separate conversation worth having through a genetic service — free, in every state — both for your own health and for your children’s. See families, carriers and genetics.

Symptoms to report, and the problem with them

What to report promptly:

• Breathlessness, particularly new or worse breathlessness lying flat
• Swelling of the ankles or abdomen
• Palpitations, or a sense of the heart racing or skipping
• Dizziness, light-headedness, or any episode of fainting or near-fainting — in a conduction-disease type this is an urgent symptom, not something to mention at the next appointment
• Chest pain or discomfort
• Reduced exercise tolerance that is new rather than gradual
• Unexplained nausea or appetite loss
• A new need to sleep propped up

And the problem, which is specific to muscular dystrophy: almost every one of those symptoms can be attributed to the muscle condition. Breathlessness gets blamed on respiratory muscle weakness. Fatigue gets blamed on the dystrophy. Reduced exercise tolerance gets blamed on weakness. Swelling gets blamed on immobility.

Some of the time that attribution is correct. The danger is that it becomes automatic, so a developing cardiomyopathy is read as the expected course of the muscle disease for months.

The practical rule: anything new or changing in the breathlessness, fatigue or exercise tolerance picture deserves a cardiac assessment rather than an assumption, and fainting deserves one urgently. It is also worth being clear that breathlessness in these conditions can be respiratory, cardiac, or both at once, and distinguishing them requires both assessments rather than a guess. See breathing and muscular dystrophy.

Surgery and anaesthesia

Every procedure in muscular dystrophy requires the cardiac status to be known and communicated.

Before any surgery, including spinal fusion, the 2018 care considerations recommend cardiology and respiratory consultation. This is not a formality — a person with reduced ejection fraction and reduced respiratory reserve is a substantially higher-risk anaesthetic, and knowing it changes the plan.

This includes minor and dental procedures under general anaesthetic. Day surgery lists do not always ask the right questions, and a dentist proposing a general anaesthetic may not know what muscular dystrophy implies.

Carry something in writing. A card or letter naming the diagnosis and subtype, the current cardiac and respiratory status, the medications including corticosteroids and the need for stress dosing where that applies, and the contact details of your neuromuscular clinic. In myotonic dystrophy, add the specific anaesthetic cautions.

Making sure it actually happens

This is the part that determines whether any of the above is real, and it is largely administrative.

In paediatric care the schedule is usually delivered because a clinic coordinator books it.

In adult care it frequently is not. Nobody owns the schedule, the specialists manage their own organ, and the annual cardiac review happens if somebody requests it. This is the central problem of adult muscular dystrophy care and it is covered in Duchenne into adulthood.

What works:

Keep your own copy of the schedule and know what is due when.

Get a GP to set up a recall system for the annual items — ECG, imaging, bloods. A GP with a recall is worth more than a specialist appointment you have to chase.

Ask at every appointment: when is my next cardiac assessment, and who is booking it?

Request copies of every report, including the actual numbers — ejection fraction, ECG findings, FVC. You will need them for other clinicians, for the NDIS, and to notice a trend.

Make sure the handover happened. At transition from paediatric to adult services, confirm that the receiving cardiologist has the history, the current medication and the most recent imaging. Do not assume a letter arrived.

And if you have not had a cardiac assessment in the last year and your diagnosis is one of the types above, that is the next phone call. It is the highest-value single action available to most people reading this.

The questions to ask at a cardiac appointment

Cardiac appointments in muscular dystrophy are frequently short, reassuring and uninformative, and the difference between a useful one and a wasted one is usually what gets asked.

“What is my ejection fraction, and what was it last time?” The single most useful number, and the trend matters more than the value. Write it down each time and keep the series. A fall from 60 to 52 per cent is more informative than either figure alone, and nobody will tell you about it unless you are tracking it.

“Have I had an ECG as well as imaging?” Because they look for different things and an echocardiogram will not detect conduction disease. In myotonic dystrophy and Emery-Dreifuss particularly, the ECG is the critical test.

“Should I be having Holter monitoring?” Twenty-four-hour rhythm monitoring detects intermittent arrhythmias that a resting ECG misses. Recommended in some conditions routinely and in others once left ventricular dysfunction or fibrosis appears.

“Should I be having cardiac MRI rather than echocardiography?” In the dystrophinopathies, MRI detects fibrosis before the ejection fraction falls, which allows treatment to start earlier. If you are still being followed with echo alone in later childhood or adulthood, ask why.

“Am I on the right medication at the right dose?” ACE inhibitors and ARBs are frequently started and then never titrated. Beta blockers and mineralocorticoid receptor antagonists have roles. Under-treatment of heart failure in this population is documented.

“When is my next assessment, and who is booking it?” The question that determines whether any of this happens, particularly in adult services where nothing is booked automatically.

“Can I have a copy of the report?” For your own records, for other clinicians, for the NDIS, and so you can notice a trend.

“Does anything about my cardiac status change what I should do about surgery, anaesthesia or exercise?” The answers are specific and useful and are rarely volunteered.

And for a relative: “Should my sister or my mother be assessed?” In X-linked conditions, carrier women need cardiac surveillance. In the lamin A/C conditions, first-degree relatives should be assessed. Both are routinely not arranged.