Cardiomyopathy

Cardiomyopathy is a disease of the heart muscle itself, not of the vessels or the valves. The wall of a heart chamber stretches, thickens or loses its give, and the pump works less well even though the arteries may be perfectly clear. Meanwhile the person feels healthy for a long time while the disease carries on. A large share of cases is inherited, so a diagnosis in one person is almost always a reason to look at the whole family.

What happens to the heart muscle

To fill with blood and push it onward, the muscle needs two abilities: to squeeze hard and to relax completely. Cardiomyopathy breaks one of them, or both at once. A stretched, thinned wall gives a weak output; a thickened, stiff wall gets in the way of filling. And if patches of scar and fat appear in the muscle, the electrical signal travels badly and rhythm disturbances come to the fore. The sensations are similar, but the dangers and the treatment differ, which is why the type is pinned down precisely.

Four main types

• Dilated. The walls of the left ventricle are stretched and thinned, and the squeeze is weak. Besides heredity, it follows inflammation of the heart muscle, long-standing heavy drinking, certain chemotherapy drugs, iron overload, untreated thyroid disease and years of uncontrolled high blood pressure. A separate form develops in the last weeks of pregnancy or the first months after birth.
• Hypertrophic. The commonest inherited heart disease: roughly one person in five hundred, and many of them do not know it. The muscle thickens with no overload at all, the chamber shrinks and the wall relaxes poorly. Sometimes the thickened septum obstructs the blood leaving the heart — the obstructive form, in which fainting on exertion occurs. It is also the commonest cause of sudden death in young athletes.
• Restrictive. Rare. The walls are not so much thick as unyielding: the heart cannot fill properly. Behind it there is especially often another disease that has laid down an abnormal protein in the muscle.
• Arrhythmogenic. Inherited: the proteins holding muscle cells together are faulty, the cells die and fat and scar grow in their place. The main feature is rhythm disturbance, often in teenagers and young adults. This is exactly the form in which endurance training speeds up the breakdown of the muscle.

Two rare but treatable causes are worth knowing, because for years they get taken for the hypertrophic or restrictive form: cardiac amyloidosis and Fabry disease. Both have a treatment of their own, and the earlier they are found the more it delivers. Certain details point towards them: carpal tunnel syndrome, a ruptured tendon, numb feet, protein in the urine, and low-voltage waves on the electrocardiogram despite an obviously thick wall on the scan. If the picture does not add up, it is fair to ask about them directly.

When shock stuns the heart

There is a form that comes on suddenly after a severe shock: losing someone close, a heavy operation, a bad fright, occasionally even great joy. The tip of the left ventricle stops contracting for a few days and balloons out, while the base works as usual. A surge of adrenaline appears to be responsible.

It looks exactly like a heart attack: crushing chest pain, breathlessness, cold sweat. Telling one from the other is only possible in hospital, so the emergency services are called either way. The heart usually recovers over weeks, but the acute days can be hard, up to fluid on the lungs, so calling this form harmless is wrong.

How it shows itself

The symptoms are non-specific and get blamed on age, weight and tiredness.

• breathlessness, at first on exertion, later with ordinary tasks and while lying flat;
• tiring quickly, a sense of having noticeably less strength for no reason;
• swollen ankles by evening and weight gain over a few days;
• palpitations, missed beats, a flip-flop feeling in the chest;
• dizziness, greying vision, fainting;
• heaviness in the chest on exertion;
• a night-time cough and waking short of breath.

In some people it all begins with a chance finding on an electrocardiogram before an operation, and that is the good scenario: the disease was caught before it announced itself.

Signs that cannot wait

Call the emergency services if there is:

• a faint, especially during physical effort, which is the most worrying sign of all;
• crushing chest pain lasting more than a few minutes;
• sudden severe breathlessness, an inability to lie down, pink frothy sputum;
• a fast irregular heartbeat together with dizziness or weakness;
• a sharp increase in swelling and breathlessness over a matter of days.

Do not put off a routine appointment either if someone in the family died suddenly before fifty or drowned while being a strong swimmer: such stories often turn out to be unrecognised heart muscle disease.

Why relatives should be checked

For many cardiomyopathies a single altered gene from one parent is enough. In the children and siblings of an affected person the chance of carrying it is appreciable, and the disease can declare itself at any age.

First-degree relatives are therefore offered an electrocardiogram and a heart scan, and after that repeat checks: a normal picture at twenty does not guarantee one at forty. If a specific mutation has been identified in the affected person, relatives can have a targeted test, and anyone who does not carry it steps out of follow-up. The decision about testing is taken with the doctor, having first talked through what will be done with the result.

What the tests show

It starts simply: the history, the examination, an electrocardiogram and a heart scan. The scan supplies the essentials — wall thickness, chamber size, the strength of contraction, how the valves behave.

After that comes whatever the situation calls for: a day-long rhythm recording, an exercise test, blood tests. Cardiac magnetic resonance imaging shows the scar and fatty tissue the scan cannot see, and it is often what separates one type from another. Less often a coronary angiogram is needed to rule out artery disease, and a muscle biopsy if inflammation or an abnormal protein deposit is suspected. Genetic testing opens the way to studying the family.

What treatment achieves

Undoing the change in the muscle is usually impossible, but symptoms can be eased, decline slowed and the risk of dangerous events genuinely reduced. Some people need no treatment at all.

Medicines are chosen by type: beta blockers, drugs acting on the renin-angiotensin system, mineralocorticoid receptor antagonists, sodium-glucose cotransporter inhibitors, diuretics for fluid retention, antiarrhythmic drugs and anticoagulants when atrial fibrillation is present. For the obstructive form there are also drugs that specifically damp down the excessive contraction of the muscle.

An important warning in the obstructive form: medicines that widen the blood vessels, and large doses of diuretics, can make things worse, as can dehydration in hot weather. Always tell any doctor your diagnosis before a new prescription.

Procedures include an implantable defibrillator when the risk of a dangerous arrhythmia is high, a pacemaker and devices that coordinate the ventricles, ablation of the arrhythmia focus and, with marked obstruction, removal of part of the thickened septum or its reduction through a catheter. In severe cases heart transplantation is on the table.

Exercise, sport and everyday life

The advice to take it easy is useless here and sometimes harmful: moderate regular activity benefits almost everyone. The question is what kind and how hard, and it is settled after the tests. Walking, unhurried swimming and cycling without bursts are usually allowed. Competitive sport, sharp accelerations and heavy lifting while holding the breath are restricted in the hypertrophic form. In the arrhythmogenic form the limits are stricter: endurance training accelerates the disease, and that applies even to mutation carriers without symptoms.

The rest is ordinary but matters: not smoking, keeping alcohol to a minimum, controlling blood pressure, sugar and weight, treating sleep apnoea. Pregnancy is planned in advance with the cardiologist: some medicines are changed and monitoring is stepped up.

Online consultation

In an online consultation the doctor goes through how long the breathlessness, palpitations or fainting have been present, asks about sudden deaths in the family, explains which tests make sense and in what order, helps make sense of reports already in hand and points out which relatives should be checked. If the signs call for urgent care, that is said straight away.

This material is for information only and does not replace medical advice.