Anthracycline chemotherapy and heart damage (cardiomyopathy): what to know

Cardiomyopathy is a general term for diseases of the heart muscle. The NHS describes it as a condition where the walls of the heart chambers become stretched, thickened or stiff, affecting how well the heart can pump blood around the body. Most types are inherited, but it can also be caused by other conditions or risk factors.

Anthracycline cardiomyopathy is a form of heart muscle weakness that can follow treatment with an anthracycline chemotherapy drug. Cancer Research UK explains that doxorubicin is an anthracycline that slows or stops cancer cells growing by blocking an enzyme they need to divide. The same page says the medicine can also cause changes to the heart muscle.

The most commonly described pattern is of the heart becoming weaker and stretched, which resembles the dilated type of cardiomyopathy that the NHS describes: the muscle walls become stretched and thin so they cannot squeeze properly. For the person affected, this can lead to heart failure. It is important to put the risk in proportion: the cancer treatment is given because it is expected to be helpful, and heart problems are one of several possible side effects that the team monitors for.

Cancer Research UK sets out three levels in its doxorubicin information. It says it is very common to have changes to the heart muscle or rhythm that are picked up on an ECHO, an ECG or both. Less commonly, doxorubicin can cause damage to the heart muscle. Rarely, this can cause heart failure.

The page also says that heart changes can happen during treatment or some months and years after you have finished. This is why follow-up heart checks are sometimes arranged after treatment has ended and why symptoms that appear later are still worth reporting, even if chemotherapy finished a long time ago.

The sources read for this page do not give dose thresholds or percentage risks for individual anthracycline drugs, so none are quoted here. Your oncologist or cardio-oncology team can explain the risk that applies to your drug, dose and other health factors.

Cancer Research UK says that before you start doxorubicin you have heart tests such as an ECHO (an ultrasound scan of the heart), an ECG (a recording of the electrical activity of the heart) or both, to check how well your heart is working. You may continue to have heart tests during and after treatment.

The NHS lists the tests used more generally for cardiomyopathy: ECG, echocardiogram, MRI scan, heart rhythm monitors worn for 24 or 48 hours, and exercise tests. If a problem is found, you may be referred to a heart specialist. Blood tests and other checks may also form part of chemotherapy monitoring.

These checks are designed to catch a change early, when it is more likely to be possible to adjust treatment or start heart-protecting medicines. If a test shows a change, the oncologist and cardiologist weigh the benefit of continuing the cancer treatment against the heart risk; this decision is individual.

Cancer Research UK says that symptoms of heart changes can include shortness of breath, ankle swelling, chest pain, and a fast, fluttering or pounding heart, and that it is important to speak with your healthcare team, or in an emergency dial 999, about any symptoms you develop.

The NHS heart failure page lists symptoms including being out of breath doing everyday activities or lying down, feeling weak, light-headed or very tired, swelling in the feet, ankles, legs or tummy, sudden weight gain, coughing at night and coughing up frothy pink phlegm.

• The NHS says to call 999 if you have severe difficulty breathing, gasping or choking, or are not able to get words out; if your lips or skin are pale, blue or grey; or if someone has passed out and is not responding normally.

• The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you feel breathless lying down or from everyday activity, are coughing up frothy pink phlegm, or have suddenly gained weight.

• If you are on chemotherapy, use the advice line number given to you by your cancer team for new symptoms; Cancer Research UK says to contact it straight away for signs of infection.

• See a GP if you have symptoms of heart failure and have had anthracycline treatment in the past, and mention it.

The NHS says there is usually no cure for cardiomyopathy but treatments can be effective at controlling symptoms and preventing complications. Not everyone needs treatment. Medicines may be needed to control blood pressure, correct an abnormal heart rhythm, remove excess fluid or prevent blood clots, and lifestyle measures such as a healthy diet, gentle exercise, stopping smoking, reducing alcohol and managing stress are advised.

If heart failure develops, the NHS says treatment aims to ease symptoms and help prevent the condition getting worse. Medicines can include diuretics to reduce fluid build-up, medicines that widen blood vessels so the heart works less hard, and beta blockers to slow the heart down. Some people need a pacemaker or an implantable cardioverter defibrillator, and everyone diagnosed with heart failure should be offered cardiac rehabilitation, the NHS says.

The NHS says heart failure symptoms can vary from day to day and that treatment and lifestyle changes can help keep it stable for many years. Cancer treatment decisions continue alongside heart care, so a joint plan between oncology and cardiology is the aim.

People who have had anthracycline treatment can reasonably ask their GP or oncology team whether they need any ongoing heart follow-up, and report breathlessness or swelling when it develops. The NHS says that if you drive and have heart failure, you will need to tell the DVLA, and you should also check with your insurance company.

In the UK, heart monitoring during chemotherapy is part of NHS cancer care. If a heart problem is found, referral is usually to NHS cardiology, and some hospitals have joint cardio-oncology clinics. Some people also use private cardiology for scans or an opinion; sharing results with the oncology team keeps decisions co-ordinated.